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+The Project Gutenberg EBook of Transactions of the American Society of
+Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910
+       The New York Tunnel Extension of the Pennsylvania Railroad
+       The Terminal Station - West
+
+Author: B.F.  Cresson, Jr
+
+Release Date: December 13, 2005 [EBook #17302]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SOCIETY OF CIVIL ENGINEERS ***
+
+
+
+
+Produced by Juliet Sutherland, Sigal Alon and the Online
+Distributed Proofreading Team at https://www.pgdp.net
+
+
+
+
+
+
+
+
+
+
+AMERICAN SOCIETY OF CIVIL ENGINEERS
+
+INSTITUTED 1852
+
+
+TRANSACTIONS
+
+Paper No. 1156
+
+
+THE NEW YORK TUNNEL EXTENSION OF THE
+PENNSYLVANIA RAILROAD.
+
+THE TERMINAL STATION-WEST.[A]
+
+BY B.F. CRESSON, JR., M. AM. SOC. C.E.
+
+
+
+
+_Location of Work._--The area covered by the work of the Terminal
+Station-West is bounded as follows: By the east line of Ninth Avenue; by
+the south side of 31st Street to a point about 200 ft. west of Ninth
+Avenue; by a line running parallel to Ninth Avenue and about 200 ft.
+therefrom, from the south side of 31st Street to the boundary line between
+the 31st and 32d Street properties; by this line to the east line of Tenth
+Avenue; by the east line of Tenth Avenue to the boundary line between the
+32d and 33d Street properties; by this line to the east line of Ninth
+Avenue. The area is approximately 6.3 acres.
+
+_House-Wrecking._--The property between Ninth and Tenth Avenues was covered
+with buildings, 94 in number, used as dwelling and apartment houses and
+church properties, and it was necessary to remove these before starting the
+construction. Most of the property was bought outright by the Railroad
+Company, but in some cases condemnation proceedings had to be instituted in
+order to acquire possession. In the case of the property of the Church of
+St. Michael, fronting on Ninth Avenue, 31st and 32d Streets, the Railroad
+Company agreed to purchase a plot of land on the south side of 34th Street,
+west of Ninth Avenue, and to erect thereon a church, rectory, convent, and
+school, to the satisfaction of the Church of St. Michael, to hand over
+these buildings in a completed condition, and to pay the cost of moving
+from the old to the new buildings, before the old properties would be
+turned over to the Railroad Company.
+
+The house-wrecking was done by well-known companies under contract with the
+Railroad Company. These companies took down the buildings and removed all
+the materials as far as to the level of the adjacent sidewalks. The
+building materials became the property of the contractors, who usually paid
+the Railroad Company for the privilege of doing the house-wrecking. The
+work was done between April and August, 1906, but the buildings of the
+Church of St. Michael were torn down between June and August, 1907.
+
+The bricks were cleaned and sold directly from the site, as were
+practically all the fixtures in the buildings. The stone fronts were broken
+up and left on the premises. Some of the beams were sold on the premises,
+but most of them were sent to the storage yards. Some of the lath and
+smaller timber was sold for firewood, but most of it was given away or
+burned on the premises.
+
+_Contracts and Agreements._--The main contract, awarded to the New York
+Contracting Company-Pennsylvania Terminal on April 28th, 1906, included
+about 502,000 cu. yd. of excavation (about 90% being rock), 17,820 cu. yd.
+of concrete walls, 1,320,000 lb. of structural steel, 638,000 ft., B.M., of
+framed timber, etc., etc.
+
+This contract was divided into two parts: "Work In and Under Ninth Avenue"
+and "Work Between Ninth and Tenth Avenues," and unit prices were quoted for
+the various classes of work in each of these divisions. The prices quoted
+for excavation included placing the material on scows supplied by the
+Railroad Company at the pier at the foot of West 32d Street, on the North
+River; there was a clause in the contract, however, by which the contractor
+could be required to make complete disposal of all excavated material at an
+additional unit price, and this clause was enforced on January 1st, 1909,
+when about 94% of the excavation had been done.
+
+For the purpose of disposing of the excavated material in the easterly
+portion of the Terminal, the New York Contracting Company-Pennsylvania
+Terminal had excavated under Ninth Avenue a cut which came to the grade of
+32d Street about midway between Ninth and Tenth Avenues, and a trestle was
+constructed from this point over Tenth Avenue and thence to the disposal
+pier at the foot of West 32d Street.
+
+On May 11th, 1906, the work of excavation was commenced on the east side of
+Ninth Avenue, and on July 9th, 1906, on the south side of 31st Street,
+between Ninth and Tenth Avenues. From the beginning, the excavation was
+carried on by day and night shifts, except on Sundays and holidays, until
+January, 1909, except that during the period from November, 1907, to
+October, 1908, the night shift was discontinued.
+
+_Geology._--The rock encountered may be classed as "gneiss"; its character
+varied from granite to mica schist. It was made up of quartz, feldspar, and
+mica, and there were also some isolated specimens of pyrites, hornblend,
+tourmaline, and serpentine. On the south side of the work, just west of
+Ninth Avenue, there were excellent examples of "contortions" of veins of
+quartz in the darker rock. On the east side of Ninth Avenue, near the north
+end of the work, glacial marks were found on the rock surface. The general
+direction of the stratification was north 5° west, and the general incline
+about 60° with the horizontal. As a rule, the rock broke sharply along the
+line of stratification. On the south side it broke better than on the north
+side, where it was usually softer and more likely to slide; and this,
+together with the fact that in winter it was subject to alternate freezing
+and thawing and in summer to the direct rays of the sun, made it rather
+difficult to get a good foundation for the retaining walls.
+
+
+WORK IN AND UNDER NINTH AVENUE.
+
+_General Description._--The work involved the excavation of about 375 ft.
+of the full width of Ninth Avenue to an average depth of about 58 ft., and
+the construction over this area of a steel viaduct, the deck of which was
+about 24 ft. below the surface, for the ultimate support of the Ninth
+Avenue structures.
+
+The following estimated quantities appear in the contract: Excavation of
+rock, 72,600 cu. yd.; excavation of all materials except rock, 9,300 cu.
+yd.; concrete (1:3:6) in abutments, etc., 1,680 cu. yd.; timber, 504,000
+ft., B.M.; structural steel, 1,320,000 lb., etc.
+
+While this excavation was being done it was necessary to support and
+maintain the three-track elevated railway structure of the Interborough
+Rapid Transit Company, of which 18 columns, or a length of about 340 ft.,
+were affected, the two-track surface railway structure of the New York City
+Railway Company, and various pipes, sewers, and conduits, and to maintain
+all surface vehicular and pedestrian traffic. All structures were left in
+place with the exception of the pipes, most of which were temporarily cut
+out. The 48-in. brick sewer in the center of Ninth Avenue was broken, and
+the sewage was pumped across the excavation through a smaller pipe.
+
+The general method adopted was as follows: The east and west sides of the
+avenue were closed, vehicular traffic was turned into the center, and a
+trestle for pedestrians was constructed west of the westerly elevated
+railway columns. All structures were then supported on transverse girders,
+running across the avenue, below the surface, and these rested on concrete
+piers on the central rock core. The sides of the avenue were then excavated
+to sub-grade, and the permanent steel viaduct was erected on both sides of
+the avenue as close as possible to the central rock core. The weight of all
+structures was then transferred to the permanent steel viaduct, erected on
+the sides of the avenue, by timber bents under the transverse girders
+resting on the permanent steel viaduct, and all weight was thus taken off
+the central rock core. This core was then excavated to sub-grade, the
+permanent viaduct was completed, and all structures were placed on its
+deck, using concrete piers and timber bents.
+
+The design and erection of the permanent steel viaduct and the permanent
+foundations on its deck were done under another contract, apart from the
+North River Division work, and are not described in this paper.
+
+_Elevated Railway Structure of the Interborough Rapid Transit
+Company._--The Ninth Avenue Elevated Railway was built between 1877 and
+1880 as a two-track structure, the design being such as to permit a third
+or central track to be added later, and this was built in 1894. It is
+supported on columns under the outside tracks, about 43 ft. from center to
+center longitudinally and 22 ft. 3 in. from center to center transversely,
+the central track being carried by transverse girders between the columns.
+
+The columns carrying the structure are of fan top design, with the points
+of bearing near the extremities at the top; each of the outside tracks is
+supported on two longitudinal latticed girders and the central track on
+two plate girders; between the columns, transverse girders are spliced to
+the outside track cross-frames, and carry the central track system. It was
+not thought desirable to put brackets on the columns near the street level
+to support the structure temporarily, and, as there is an expansion joint
+at each column, and as the transverse girders carrying the central track
+system are not rigidly attached to the longitudinal girders carrying the
+outside tracks, the central track could not be supported by supporting the
+outside tracks; therefore, independent supports for each track, in the form
+of overhead girders, had to be provided. The columns rest on brick piers,
+each having four 2-in. anchor-bolts. The brick foundations on the west side
+are wide in order to allow a 24-in. water main to pass directly beneath the
+columns. The foundations are usually on rock.
+
+[Illustration: PLATE XLVII, FIG. 1.--TW 4, P.N.Y. & L.I.R.R. Terminal
+Station West. View of 9th Ave. looking Northwest from 32nd Street, prior to
+commencement of work. April 23, 06.]
+
+[Illustration: PLATE XLVII, FIG. 2.--TW 17, P.N.Y. & L.I.R.R. Terminal
+Station West. View of East side of 9th Ave. looking North from a point 100
+feet south of 33rd St. showing condition of work. July 23, 06.]
+
+[Illustration: PLATE XLVII, FIG. 3.--TW 25, P.N.Y. & L.I.R.R. Terminal
+Station West. View showing permanent and temporary supports of 9th Ave.
+Structures, looking Northwest from 31st. St. April 24, 07.]
+
+[Illustration: PLATE XLVII, FIG. 4.--TW 28, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Avenue, North of 32nd St. looking West,
+showing rock excavation and supports of 9th Avenue structures. Aug. 17,
+07.]
+
+Fig. 1, Plate XLVII, shows the elevated railway structure and the street
+surface prior to the commencement of the work.
+
+The east track is used for north-bound local trains, the west track for
+south-bound local trains, and the central track for south-bound express
+trains between 7 and 9.30 A.M. and for north-bound express trains between
+2.30 and 7 P.M. It is said that an average of 90,000 passengers are carried
+over this structure every 24 hours.
+
+_Surface Railway Structure of the New York City Railway Company._--This is
+an electric surface railway of the ordinary type, the rail and slot being
+bedded in concrete, with cast-iron yokes every 5 ft. There are manholes
+every 100 ft., and cleaning-out holes every 15 ft. Power conduits are
+bedded in the concrete on the east side of the east track.
+
+_Forty-eight-Inch Brick Sewer._--This sewer was in the center of Ninth
+Avenue, with the invert about 12 ft. below the surface, and manholes about
+100 ft. apart, and had to be abandoned in this position to allow the
+transverse girders to be put in place to carry all structures while the
+excavation was being done.
+
+_Twenty-four-Inch Cast-Iron Water Main._--This water main was laid under
+the west elevated railway columns, with its top about 3 ft. below the
+surface, a space being left for it in the brick foundations, and a large
+column base casting being used to span it. Valves were installed, one north
+of 33d Street and one south of 31st Street, prior to excavating near the
+pipe, so that if it was broken the water could be shut off promptly.
+
+_Street Surface._--It was the original intention to close and excavate the
+east side of the avenue and to erect there a street-traffic trestle before
+closing the west side, but, at the contractor's request, both sides were
+closed, and all vehicular traffic was turned into the center. A light
+trestle on the west side of the avenue provided for pedestrian traffic.
+
+_Other Sub-surface Structures._--There were various gas mains, water mains,
+electric conduits, manholes, hydrants, etc., in the avenue, and most of
+these were cut out temporarily, at the contractor's request, to be replaced
+subsequently.
+
+_Supports for Elevated Railway Structure._--As stated previously, the
+central track had to be supported independently.
+
+The overhead girders, known as girders "B", were therefore designed as
+shown on Fig. 1, and put in place as shown on Figs. 2 and 3. The outside
+tracks were blocked directly on these girders, and the central track was
+supported by blocking up the transverse girders on I-beams placed between
+the girders "B"; and no blocking was placed between the girders "B" and the
+longitudinal girders carrying the central track. The weight on each column
+was assumed to be 172,000 lb.
+
+[Illustration: FIG. 1. (Full page image)
+
+DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES]
+
+_Supports for Surface Railway Structure._--A uniform load of 3,000 lb. per
+lin. ft. of single track, with the weight of a car at 39,000 lb., was
+assumed. Several feet of earth, between the structure and the rock, were
+mined out, and the structure was supported on I-beams and posts, and
+ultimately on the transverse girders by using timber bents under the
+I-beams, as shown on Fig. 3.
+
+_Water Mains and Sewer._--Cradles were designed for the support of the
+48-in. and 24-in. water mains, resting on the transverse girders, and the
+48-in. cast-iron sewer on the east side of the avenue was carried on
+I-beams bracketed to the ends of the transverse girders, as shown on Figs.
+1 and 2.
+
+[Illustration: FIG. 2. (Full page image)
+
+METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE]
+
+[Illustration: FIG. 3. (Full page image)
+
+METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO.]
+
+_Girders "C."_--The transverse girders below the street surface, referred
+to above, were known as girders "C," and they were put in place at first
+resting on concrete piers on the central core; the weight of all structures
+was placed on them while the sides of the avenue were being excavated, and
+the sides of the viaduct were being built. The ends of these girders were
+then picked up on the sides of the viaduct, and, spanning the central rock
+core, carried all structures while the core was being excavated and the
+viaduct completed. New foundations were then placed on the deck of the
+viaduct to carry all structures.
+
+Fifty-four of these girders were required, each weighing about 19,000 lb.
+The bents carrying the ends of these girders on the sides of the viaduct
+are shown on Fig. 2. They were of long-leaf yellow pine. These girders were
+located so that a cradle could be laid on them east of the elevated railway
+structure to carry a proposed 48-in. cast-iron water main.
+
+_Girders "B."_--Eighteen of these girders were required, each weighing
+about 6,000 lb. The timber bents supporting these girders, shown on Fig. 2,
+were of long-leaf yellow pine.
+
+The total weight, including the elevated railway structure, surface railway
+structure, pipes, etc., supported during the work, amounted to about 5,000
+tons.
+
+_Details of the Work._--The method in general is shown on Figs. 4 and 5. At
+first the east side of the avenue was closed and excavated down to rock,
+the earth was mined out under alternate yokes of the surface railway
+structure, and temporary posts were placed under the yokes to support the
+structure while the remainder of the earth was being removed. Then
+needle-beams and posts were placed under each yoke. The concrete forming
+the track structure was then enclosed with planking to prevent it from
+cracking and falling. I-beams were then placed under the needle-beams
+carrying the structures, and these were carried on posts; they were changed
+alternately until the excavation had been taken out to a depth of about 16
+ft. below the surface. In placing these I-beams, heavier blocking was used
+in the center of the span than at the ends where the bents would come, to
+prevent the subsidence of the track owing to the sag in the I-beams. As
+much excavation, to a depth of about 20 ft., was taken out adjoining the
+elevated railway foundations as could be done with safety. Fig. 2, Plate
+XLVII, shows this condition of the work. The 48-in. brick sewer was broken,
+and the sewage was pumped across the excavation.
+
+The overhead girders "B" were then put in place, and two of the girders "C"
+were used as temporary shoring girders at each column. These, as shown by
+Fig. 3, Plate XLVII, were placed parallel to the elevated railway, with
+blocking between them and the girders "B." Double bents, independent
+of each other, were placed under the ends of these temporary shoring
+girders, and these were braced securely to prevent possible dislodgment
+during the removal of the rock. The weight of the structure was then taken
+by jacking up the girders near the bents until the column was lifted off
+the old foundation; blocking was put in between the girders and the bents
+during the jacking, so that when the jacks were released the base of the
+column was still clear of the old foundation. One 80-ton jack was used for
+this purpose, and the general method is shown by Fig. 1, Plate LII.
+
+[Illustration: FIG. 4. (Full page image)
+
+METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES
+OF THE WORK]
+
+[Illustration: FIG. 5. (Full page image)
+
+METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK
+
+No. 1
+
+Condition Prior to Commencement of Work
+
+No. 2
+
+East side of Avenue cut down about 20 ft. Beams with Supporting Posts
+placed under Surface Railway Tracks. Girders _B_ and Temporary Shoring
+Girders _C_ for supporting Elevated Ry. in place.
+
+No. 3
+
+I's in place under Surface Ry. Tracks. Elevated Ry. carried on Temporary
+Shoring Girders, and Girders _C_ in place. 24" Water Main carried on Timber
+Cradle and sewage carried through Pipe _R_. Foot Walk carried on Girders
+_C_ in place on West Side of Avenue.
+
+No. 4
+
+Elevated Railway carried on Bents under Columns. Temporary Shoring Girders
+removed and Permanent Bents resting on Girders _C_ in place. Bents in place
+on Girders _C_ carrying Surface Railway. East and West sides of Avenue
+excavated down to Sub-Grade and Five rows of Permanent Steel in place on
+each side. Bents erected on Permanent Steel to catch ends of Girders _C_
+while 2 outside Concrete Piers are removed and 6th row of Permanent Steel
+on each side is put in place.
+
+No. 5
+
+Two outside Concrete Piers removed and 6th row of Permanent Steel in place.
+Girders _C_ carrying all structures now resting on Bents on Permanent
+Steel. 48" C.l. Sewer carried on Brackets on Girders _C_.
+
+No. 6
+
+Excavation Completed. ]
+
+Temporary raker braces were placed against the structure to prevent lateral
+movement. Four sets of these temporary shoring girders were used in this
+manner, two sets starting at the north end and two sets at about the middle
+of the work, and these sets were moved south as they were released.
+
+The columns being thus supported on temporary shoring girders, the old
+foundations were removed and the excavation was taken down to a level about
+16 ft. below the surface.
+
+Two sets of three of the girders "C" were then put in place under the
+avenue at each column, each set being placed on four concrete piers 6 ft.
+square with spaces of 4 ft. between them, so that the outside of the
+outside pier would be 18 ft. from the center of the avenue and 32 ft. from
+the house line. This is shown on Fig. 5 and on Fig. 3, Plate XLVII. Four
+small piers were used, as they could be more easily removed than one
+continuous pier. The girders "C" were set to line and grade, and the piers
+were built under them, great care being taken to get the concrete well
+under the girders so as to give a firm bearing.
+
+After these girders "C" were in place it was necessary to remove the
+temporary shoring girders before the bents could be erected on girders "C"
+to support girders "B," being in the same plane; and provision had to be
+made to support the structure while this was being done. Therefore, double
+bents were erected directly beneath the columns, as shown by Figs. 2, 4,
+and 5, and by Fig. 3, Plate XLVII. These were built with their sills
+resting on the girders "C," and blocking was put in between the sills and
+the rock to carry the full weight of the structure. Later, when the weight
+of the structure was carried on the permanent bents, this blocking was
+knocked out, but the bents were left in to carry the weight of the column
+itself, which was swinging more or less from the structure above. The
+weight of the structure was placed on these bents directly beneath the
+columns by jacking up the temporary girders again, putting blocking between
+the bents and the base of the columns, and taking out the blocking which
+had been put in previously under the temporary shoring girders. The 24-in.
+water main was carried over the excavation on cables from the temporary
+shoring girders, except when they were being jacked up, at which time posts
+were placed beneath it.
+
+Anchor-bolts were put in place between the column bases and the bents
+directly beneath, in order to increase the lateral stiffness, and raker
+braces were also used. This having been done, the temporary shoring girders
+were moved south to the next column, where the process was repeated. The
+timber bents, shown in detail by Fig. 2, were then put in place as shown by
+Figs. 4 and 5, and by Fig. 3, Plate XLVII. These bents were framed as
+tightly as possible, using generally a 20-ton jack, and they were erected
+simultaneously at each pair of columns. The weight was taken on these
+columns by jacking up directly beneath the column base and taking out the
+blocking between this base and the bent directly beneath the column. On
+releasing the jack the weight was transferred to the permanent timber
+bents, and the east and west columns of each pair were transferred on the
+same day. One 80-ton jack was used on the easterly columns and two were
+necessary on the westerly columns, one on each side of the 24-in. water
+main. The raker braces of these permanent bents were not framed as tightly
+as the main posts, in order that the main post should carry the entire
+weight and the raker braces merely steady the structure.
+
+Timber bents were erected on girders "C" to carry the I-beams under the
+surface railway structure, as shown on Fig. 3, and all temporary posts
+under these I-beams were removed. The bents were framed with a jack, as
+tightly as possible, and very little settlement of the track occurred.
+
+A cradle was then built under the 24-in. water main and placed on girders
+"C," and, as a temporary footwalk had been constructed on the west side of
+the avenue, it will be seen that all structures were thus carried on
+girders "C."
+
+All structures were put on the girders "C" before continuing the excavation
+on the sides of the avenue because, in case of a slide of rock, there would
+be less danger than to individual structures. The outside piers, on
+which the girders "C" rested, might even be lost, without affecting the
+stability of the structure, and posting could readily be done beneath these
+girders in case of necessity.
+
+A very careful record of levels, taken on the elevated railway columns, was
+kept, observations being made during each jacking up and at least twice a
+week during the progress of the work. The columns were usually kept about
+1/2 in. high so as to allow for compression in the timber bents.
+
+As a rule, no jacking of the elevated railway structure was done while
+trains were passing over, and trains were flagged during the operation.
+There was generally very little delay, as all jacking was done between
+10.30 A.M. and 2.30 P.M., when the traffic was lightest, and frequently the
+jacking was done between trains, causing no delay whatever. Steel clamps
+were placed, three on the top and three on the bottom of each set of the
+girders "C," to bind them together and cause them to act as a unit.
+
+All structures then being supported on girders "C," which were carried on
+four concrete piers resting on the central rock core, the excavation on the
+sides of the avenue was continued down to sub-grade and the east and west
+portions of the concrete north abutment were constructed. The central rock
+core was about 36 ft. wide on the top and 45 ft. wide on the bottom, and at
+the center of 32d Street it was about 42 ft. high.
+
+It was the original intention to excavate a sufficient width of the sides
+of the avenue to erect six rows of the permanent steel viaduct, 5 ft. from
+center to center, and this was done on the south portion of the work. On
+the north portion, however, the rock was of poor quality, and it was
+thought best to excavate for only five rows at first, to erect the five
+rows of permanent steel and put the timber bents in place under the ends of
+the girders "C," in order to give them some support while the outside
+concrete piers were being removed and the excavation was being widened out
+to permit the erection of the sixth row. Additional raker braces were put
+in these bents temporarily, and were removed when the sixth row of steel
+had been erected. This is shown on Figs. 4 and 5.
+
+[Illustration: PLATE XLVIII, FIG. 1.--TW 33, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Ave. looking North from 31st St., showing
+rock excavation and supports of 9th Ave. structures. Dec. 28, 07.]
+
+[Illustration: PLATE XLVIII, FIG. 2.--TW 39, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Ave. looking North from 31st Street, showing
+rock excavation and permanent steel work. March 24, 08.]
+
+[Illustration: PLATE XLVIII, FIG. 3.--TW 73, P.T. & T.R.R. Co. Terminal
+Station West. West side of Ninth Ave. Jacking up girders "C" at Elevated
+Railroad Column 491, showing method of taking weight on permanent viaduct
+girders. Nov. 14, 08.]
+
+[Illustration: PLATE XLVIII, FIG. 4.--TW 58, P.T. & T.R.R. Co. Terminal
+Station West. East side of Ninth Ave. looking North from 31st St., showing
+underpinning of Ninth Ave. Structures. Aug. 10, 08.]
+
+Fig. 4, Plate XLVII, and Fig. 1, Plate XLVIII, show the structures
+supported on the central rock core and the excavation on the east side to
+permit of the erection of the permanent viaduct girders. Fig. 1, Plate
+XLVIII, shows also the easterly portion of the concrete north abutment.
+Fig. 2, Plate XLVIII, shows five rows of the permanent viaduct girders
+erected on the east side of the work.
+
+The excavation of the sides of the avenue having been completed, and six
+rows of permanent viaduct girders erected on both sides, timber bents, as
+shown on Figs. 2, 4, 5, and 6, were erected on this steel to support the
+ends of the girders "C" and carry the structure while the rock core was
+being excavated. Fig. 3, Plate XLVIII, shows the method of taking the
+weight on these bents. Four 80-ton jacks were used, and oak blocks were
+placed on the top of each jack to transmit pressure to a temporary oak cap
+under the girders "C" independent of the bents; all four of these jacks
+were operated simultaneously, and the girders "C" were lifted off the bents
+and clear of the concrete piers. Oak filling pieces were then inserted
+between the bents and the girders "C," so that when the jacks were released
+the girders "C" were clear of the concrete piers. Fig. 3, Plate XLVIII,
+shows that the girders have been lifted off the piers. Elevations were
+taken on each set of girders during each operation, and careful
+observations were made on the elevated railway columns. Where the rock was
+very close to these bents, the open space between the posts was filled with
+blocking so that there would be less danger of the bent shifting if struck
+by blasted materials. Fig. 3, Plate XLVIII, shows one of these bents filled
+with blocking.
+
+All structures being carried on girders "C," which, in turn, were carried
+on the sides of the permanent viaduct, the central core was excavated. Fig.
+4, Plate XLVIII, and Figs. 1, 2, 3, and 4, Plate XLIX, show various views
+of the work at this stage.
+
+The central portion of the viaduct was then erected, and, using concrete
+piers and timber bents, all structures were placed on its deck. Fig. 3,
+Plate XLIX, shows the piers under the elevated railway columns prior to the
+removal of girders "C."
+
+[Illustration: FIG. 6. (Full page image)
+
+GENERAL ARRANGEMENT OF TEMPORARY AND PERMANENT STRUCTURES]
+
+During the latter part of 1908 a 48-in. cast-iron water main was laid by
+the city on a cradle built by the Railroad Company on girders "C" on the
+east side of the avenue. This is part of the high-pressure system, and the
+location and elevation of this water main were taken into consideration
+when the underpinning was designed. This main, and the 48-in. cast-iron
+sewer bracketed to girders "C," are shown on Fig. 4, Plate XLVIII.
+
+Elevations had been taken on marks on the elevated railway columns
+between 30th and 34th Streets at the time the original surveys were made,
+in 1902, and these marks were used to test the level of the structure
+during the progress of the excavation.
+
+At the extreme south end of the work the procedure was changed. The east
+side was excavated down to sub-grade, the east portion of the south
+abutment was constructed, and six rows of the permanent steel viaduct were
+erected. Very little excavation had been done on the west side of the
+avenue at the south end of the work, and it would have delayed the
+completion of the work to have waited for the excavation for and the
+construction of the west portion of the south abutment and the erection of
+the steel; therefore, instead of supporting the girders "C" on the central
+rock core, the east ends were taken up on the permanent viaduct girders,
+and the west ends were supported on a concrete pier on the rock. The
+central portion of the avenue was excavated in advance of the west portion.
+The permanent viaduct girders were put in place from east to west across
+the avenue, and the girders "C" were supported on the deck of the permanent
+viaduct approximately under the west elevated railway columns before the
+west portion of the avenue was excavated, the central portion of the south
+abutment having been constructed before the west portion. This procedure
+was adopted only at the north girders "C" at elevated railway column No.
+488, the south set of girders "C" being on the rock immediately south of
+the south abutment. Figs. 2 and 4, Plate XLIX, and Fig. 2, Plate LII, show
+various stages of the work at the south end.
+
+[Illustration: PLATE XLIX, FIG. 1.--TW 60, P.T. & T.R.R. Co. Terminal
+Station West. Under Ninth Ave., looking South from North abutment, showing
+underpinning and excavation of rock core. Aug. 13, 08.]
+
+[Illustration: PLATE XLIX, FIG. 2.--TW 84, P.T. & T.R.R. Co. Terminal
+Station West. View looking toward Ninth Ave. from South side of 31st St.,
+200 feet West of Ninth Ave. Jan. 28, 09.]
+
+[Illustration: PLATE XLIX, FIG. 3.--TW 88, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. Center line of 32nd St., looking East from Sta.
+183+50, showing excavation under Ninth Avenue, permanent concrete piers
+under Elevated Railway Columns and removal of temporary shoring girders
+"C". April 8, 09.]
+
+[Illustration: PLATE XLIX, FIG. 4.--TW 95, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. View under Ninth Avenue looking Southward from 100
+feet South of center line, showing underpinning of Ninth Avenue structure
+taken at sub-grade. May 25, 09.]
+
+It was made a practice all through the work to transfer the weight of the
+structures very positively from one support to another by lifting them
+bodily by jacks, and putting in filler pieces before releasing the jacks,
+not trusting to wedging to transfer the loads. In fact, apart from the
+boxing-in of the surface railway concrete, no wedges whatever were used.
+This appears to have been a decided advantage, for, with the constant
+pounding of trains on the elevated railway and the jarring due to heavy
+trucks on the pavement blocks, it is very likely that wedging would have
+become loosened and displaced, whereas, with blocking, there was little or
+no tendency toward displacement due to vibration. Although the vibration of
+the structure, when a long length was supported on girders "C" resting on
+the permanent viaduct girders on the sides of the avenue, appeared to be
+considerable, not only vertically but transversely, very careful
+observation showed that the sag in the girder "C" due a live load of three
+elevated railway trains, one surface railway car, and one heavy truck,
+amounted to 1/8 in. The sideway vibration did not amount to more than 1/32
+in. on either side of the normal position. More vibration was caused by
+heavy trucks and wagons going over the stone pavement than by the elevated
+railway trains or surface cars.
+
+No blasting was done near the supports of the elevated railway structure
+while trains were passing over it, and occasionally trains were stopped
+during a heavy or uncertain blast. A watchman on the surface, day and
+night, and at first one and later two flagmen on the elevated railway
+structure, were on duty at all times, reporting to the Interborough Rapid
+Transit Company, by whom they were employed. Log mats and timber protection
+for the girders and the columns of the permanent viaduct were used, as
+shown by Figs. 1 and 4, Plate XLIX, during the excavation of the rock core,
+and timber was also used to protect the face of the completed portions of
+the concrete abutments.
+
+In excavating the sides of the avenue, the rock broke better on the east
+than on the west side, where large seams developed and some slides
+occurred.
+
+_Abutments._--As shown on Fig. 7, the face of the north abutment has a
+batter of 2 in. to the foot, and the face of the south abutment has a
+variable batter, the base being on a grade and the bridge seat being level,
+and both maintaining a uniform distance from the center of the Terminal
+Yard. The back walls of the abutments were not built until the steel had
+been put in place.
+
+No attempt was made to water-proof these abutments, but, in the rear of the
+wall, open spaces were left, about 6 ft. from center to center, which were
+connected with drain pipes at the base of and extending through the wall,
+for the purpose of carrying off any water that might develop in the rock.
+These drains were formed by building wooden boxes with the side toward the
+rock open and the joints in the boxes and against the rock plastered with
+mortar in advance of the wall. A hose was used to run water through these
+drains during the placing of the concrete, for the purpose of washing out
+any grout which might run into them. Each box was washed out at frequent
+intervals, and there was no clogging of the drains whatever. This method
+of keeping the drains open was adopted and used successfully for the entire
+work. The abutments were built of concrete, and the mixture was 1 part of
+cement, 3 parts of sand, and 6 parts of broken stone.
+
+The concrete was mixed in a No. 3 Ransome mixer, and was placed very wet.
+No facing mixture or facing diaphragms were used, but the stone was spaded
+away from the face of the wall as the concrete was laid. Chutes were used
+inside the form, if the concrete had to drop some distance. Work was
+continued day and night, without any intermission, from the time of
+commencement to the time of completion of each section.
+
+The face of the concrete wall was rubbed and finished in a manner similar
+to that used on the walls between Ninth and Tenth Avenues, as described
+later.
+
+Fig. 2, Plate LII, shows the east and central portions of the south
+abutment, completed and carrying the permanent viaduct, and the excavation
+completed for the west portion.
+
+
+WORK BETWEEN NINTH AND TENTH AVENUES.
+
+_General Description._--The work involved the excavation of about 5.4
+acres, between the west house line of Ninth Avenue and the east house line
+of Tenth Avenue, to an average depth of about 50 ft., the construction of a
+stone masonry portal at Tenth Avenue leading to the River Tunnels, and the
+construction around the site of the concrete retaining and face walls.
+
+The following estimated quantities appear in the contract: Excavation of
+rock in trenches, 3,400 cu. yd.; excavation of rock in pit, 377,000 cu.
+yd.; excavation of all materials except rock in trenches, 6,500 cu. yd.;
+excavation of all materials except rock in pit, 34,000 cu. yd.; concrete,
+1:3:6, in retaining walls, 4,580 cu. yd.; concrete, 1:3:6, in face walls,
+7,460 cu. yd.; concrete, 1:2:3, with 3/4-in. stone, in face walls, 4,100
+cu. yd.; stone masonry in portal, 247 cu. yd., etc., etc.
+
+[Illustration: Fig. 7. (Full page image)
+
+NINTH AVE. ABUTMENTS & KEY PLAN]
+
+As previously stated, the contract price included the placing of all
+excavated material on scows at Pier 62, North River. Prior to this contract
+this pier had been used by the New York Contracting Company-Pennsylvania
+Terminal, for the disposal of excavated material from east of Ninth
+Avenue. In order to get the material to the pier, the contractor had
+excavated a cut under Ninth Avenue which came to the grade of 32d Street
+about midway between Ninth and Tenth Avenues, and a trestle was constructed
+from this point over Tenth Avenue and thence to the pier. Fig. 2, Plate
+XLVII, shows the east end of this cut, and Fig. 1, Plate L, shows the
+trestle, looking east from Tenth Avenue.
+
+A 30-ton steam shovel was brought to the south side of the work, and
+commenced operating on July 9th, 1906. After working there about a month,
+the earth had been practically stripped off the rock, and the shovel was
+moved over to the north side where it excavated both earth and rock until
+August 10th, 1907.
+
+At three points south of 32d Street and at one point north of 32d Street
+near Tenth Avenue, cuts were made in the rock to sub-grade, and from these
+cuts, together with the cuts on the west side of Ninth Avenue, all widening
+out was done and the excavation was completed. Fig. 1, Plate L, shows the
+excavation of the three cuts on the south side of 32d Street, the steam
+shovel operating on the north side of that street, and the
+material-disposal tracks and trestle. Fig. 3, Plate LII, shows the cuts
+joined up and the excavation along the south side practically completed.
+
+On the north side of the work, between Stations 182 + 90 and 183 + 65, the
+rock was low, and provision had to be made for maintaining the yards to the
+north of the site. Therefore a rubble-masonry retaining wall was built,
+with the face about 2 ft. north of the face of the proposed concrete wall
+which was to be put in later. On the same side of the work, between
+Stations 188 + 24 and 188 + 46, the rock was exceedingly poor, and as a
+small frame house on the adjoining lot was considered to be in an unsafe
+condition, a rubble masonry retaining wall was built. As the building
+adjoining the south side of the work at Tenth Avenue was on an earth
+foundation, it was necessary to underpin it before the excavation could be
+done. The building was supported on needles, and rubble masonry was put in
+from the bottom of the old foundation to the rock. The foundation of 413
+West 31st Street, immediately west of the Express Building site, was of
+very poor masonry, and it was necessary to rebuild it prior to taking out
+the adjoining excavation.
+
+[Illustration: PLATE L, FIG. 1.--TW 23, P.N.Y. & L.I.R.R. Terminal Station
+West. View looking Eastward from Tenth Ave., showing work between Ninth &
+Tenth Avenues. Dec. 26, 06.]
+
+[Illustration: PLATE L, FIG. 2.--TW 35, P.T. & T.R.R. Co. Terminal Station
+West. View looking Northwest from Sta. 184, 120 feet South of center line.
+Dec. 31, 07.]
+
+[Illustration: PLATE L, FIG. 3.--TW 96, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. View looking West from Ninth Avenue Elevated
+Railway, showing condition of work. May 26, 09.]
+
+[Illustration: PLATE L, FIG. 4.--TW 104, P.N.Y. & L.I.R.R. Terminal Station
+West. View from Tenth Avenue looking East, showing progress of concrete
+walls. Aug. 7, 09.]
+
+Along the north side, between Stations 186 + 50 and 187 + 50, the walls
+supporting the adjoining back yards were of poor quality and had to be
+renewed by the contractor before excavation could be done.
+
+The excavated material was loaded by derricks on cars at the top of the
+excavation, these cars being on tracks having a direct connection with the
+disposal trestle, as shown by Fig. 1, Plate L. As soon as it could be done,
+derricks were placed at the bottom of the excavation; tracks were then laid
+out there, and the excavated material was loaded on cars at the bottom and
+hoisted by derricks to cars on the disposal trestle. A locomotive was
+lowered to the bottom of the excavation on August 25th, 1907, and a derrick
+started operating at the bottom on August 27th, 1907. The commencement of
+this work by derricks at the bottom is shown by Fig. 3, Plate LII. In
+general, the disposal tracks were maintained about on the center line of
+31st Street until the excavation had been carried as close to them as
+possible, and on October 16th, 1907, they were shifted to the extreme north
+side of the work, as shown by Fig. 2, Plate L. A portion of the old trestle
+was left in place near Tenth Avenue, a derrick was erected thereon, and the
+tracks were used for cars to receive the excavated material hoisted from
+sub-grade. The disposal trestle was maintained in this position until such
+time as it would interfere with the excavation, and then the tracks were
+abandoned. This was done on November 11th, 1908. Fig. 3, Plate L, shows the
+finishing of the excavation on the north side of the work. On August 30th,
+1908, a cut was made under Ninth Avenue at sub-grade, and cars could then
+be run from Seventh to Tenth Avenue at sub-grade. On October 24th, 1908,
+the connection with the disposal trestle east of Ninth Avenue was
+abandoned, and all excavated material was hoisted from sub-grade at Tenth
+Avenue by derricks.
+
+As previously stated, the contractor was required to make complete disposal
+of all excavated material after January 1st, 1909, but was allowed the use
+of the pier until January 20th, 1909, after which date the materials were
+hoisted by derricks at Tenth Avenue, loaded on 2-horse trucks, and
+transported to the 30th Street pier, North River, where it was loaded on
+scows by two electric derricks. A considerable amount of the rock
+excavation was broken up and used for back-fill.
+
+_Earth Excavation._--Practically all the earth excavation, amounting to
+about 57,000 cu, yd., was done with steam shovels. The average quantity of
+earth excavated by a steam shovel per 10-hour shift was 180 cu. yd. This
+material was loaded on side-dump cars and taken to the disposal pier where
+it was dumped through chutes to the decks of scows. Inasmuch as the
+quantity of earth excavation was small, as compared with the rock, the
+earth was used principally for the first layer on the scows for padding, so
+that small stones might be dumped through the chutes without injuring the
+decks.
+
+_Rock Excavation._--As previously stated, the rock broke better on the
+south than on the north side, where there were several slides, and
+considerable excavation had to be taken out beyond the neat line required
+in the specifications. The worst slide occurred at midnight on July 3d,
+1909, at about Station 188 + 50. The last blast, to complete the excavation
+to sub-grade at this point, had been fired in the afternoon of the same
+day, and the mucking was practically completed. Great care had been taken
+in excavating near this point, as it was evident that the rock was not of a
+very stable character, but, when the excavation had been completed, it was
+thought that the rock remaining in place would stand. The volume of
+material brought down by this slide amounted to about 200 cu. yd. The rock
+on the south side broke very well, and there were no slides of any
+consequence.
+
+The drill holes were laid out by the blaster, and the general method of
+drilling for different classes of work was as follows: In breaking down,
+the holes were started about 8 ft. apart, on a slight batter, so that at
+the bottom they would be considerably less than 8 ft. apart. They were
+drilled about 10 ft. deep, and blasting logs were used, as it was necessary
+to load quite heavily in order to lift the material and start the cut.
+After the cut had been made, side holes were shot to widen out sufficiently
+to start another cut.
+
+After a side cut about 20 ft. deep had been made, the side holes were
+drilled 20 ft. deep, and the holes were loaded and tamped for the full
+20-ft. cut. Under the terms of the specifications, the contractor was
+required to complete the excavation on the sides by drilling broaching
+holes.
+
+The maximum length of drill steel was about 20 ft., and, where the
+excavation plane of broaching was more than 20 ft. in depth, the contractor
+was permitted to start the holes back of the broaching line, in order to
+allow for setting up the drills on the second lift. A distance of about 8
+in. was usually allowed for setting up a drill. The broaching line was
+painted on the surface of the rock in advance of the drilling, and the
+batter of the drill was tested with a specially designed hand-level in
+which the bubble came to a central position when the face of the level was
+on the required batter. Holes were also drilled in front of this broaching
+line, and, when the excavation had been taken out to within about 6 ft. in
+front of it, the holes immediately in front were loaded, and also about
+every third one of the broaching holes, and, unless the rock was very bad,
+it usually broke sharply at the broaching line. Occasionally, the broaching
+holes which were not loaded were filled with sand, which gave rather better
+results than leaving them open.
+
+In the steam-shovel work on the east side of Ninth Avenue, spring holes
+were used. They were formed by drilling a 20-ft. hole and exploding at the
+bottom of it, without tamping, two or three sticks of dynamite, and
+repeating this process with heavier charges until there had been formed at
+the bottom of the hole a large cavity which would hold from 100 to 200 lb.
+of dynamite. Face holes and breast holes were also drilled, and it was
+possible by this method to drill and break up a cut 20 ft. deep and 15 ft.
+thick. The only place where spring holes were used on this work was on the
+east side of Ninth Avenue where the heavy cutting was sometimes extended
+beyond the east house line.
+
+From the best records obtainable, the average progress in drilling was
+about 33 lin. ft. per 8-hour shift. The average number of cubic yards of
+excavation per drill shift was 13.9, and the average amount of drilling per
+cubic yard of excavation was 2.4 ft.; this covered more than 27,000 drill
+shifts.
+
+The dynamite was practically all 60%, and the average excavation per pound
+of dynamite was 2.2 cu. yd. The contractor employed an inspector of
+batteries and fuses, who, using an instrument for that purpose, tested the
+wiring of each blast prior to firing, in order to discover any short
+circuits, and thus prevent the danger of leaving unexploded dynamite in the
+holes.
+
+The average quantity of excavation per derrick shift of 10 hours, covering
+7,400 shifts, 87% of the excavation being rock, was 50 cu. yd., and the
+average force per shift, including only foreman and laborers, was 13 men.
+It was found that a derrick operating at the top of a 20-ft. cut would
+handle about 40 cu. yd. per shift, whereas, if operating at the bottom of
+the cut, it would handle about 60 cu. yd. per shift. The elevator derricks
+at Tenth Avenue were very efficient, and each could take care of the
+material from four derricks at the bottom, hoisting 250 cu. yd. per shift a
+height of 60 ft.
+
+_Concrete Retaining and Face Walls._--It was essential to have the greatest
+space possible at the bottom of the excavation, and, inasmuch as the yard
+was to be left open, it was necessary to provide some facing for the rock
+on the sides in order to prevent disintegration, due to exposure, and give
+a finished appearance to the work. Above the rock surface a retaining wall
+of gravity section was designed, the top being slightly higher than the
+yards of the adjoining properties. The face wall was designed to be as thin
+as possible, in order to allow the maximum space for tracks.
+
+The excavation, therefore, was laid out so that the back of the retaining
+wall would not encroach on the adjoining property, but would practically
+coincide with the property line at positions of maximum depth.
+
+The batter on the face of the wall was 2 in. per ft., and a bridge seat
+3-1/2 ft. wide was formed at an elevation of 22 ft., minimum clearance,
+above the top of the rail. This bridge seat was made level. The maximum
+height of the south wall is 49 ft., and of the north wall 65 ft.
+
+The face walls were classed as "Upper Face Walls," extending from the base
+of the retaining wall to the bridge seat, and as "Lower Face Walls,"
+extending from the bridge seat to the base of the wall. The general design
+is shown on Fig. 8.
+
+In considering the design of the face wall it was felt that, the wall being
+so thin, ample provision should be made to prevent any accumulation of
+water and consequent pressure back of the wall; therefore, no attempt was
+made to water-proof it, but provision was made to carry off any water which
+might appear in the rock. Box drains, 2 ft. wide and 6 ft. from center to
+center, were placed against the rock, so that, there being but 4 ft.
+between the drains, and the wall having a minimum thickness of 2 ft., any
+water in the rock would not have to go more than 2 ft. to reach a drain,
+and would probably pass along the face of the rock to a drain rather than
+through 2 ft. of concrete. These drains were connected with pipes leading
+through the wall at its base.
+
+[Illustration: FIG. 8. (Full page image)
+
+RETAINING AND FACE WALLS NORTH SIDE]
+
+These box drains occurred so frequently, and decreased the section of the
+wall so materially, that it was thought desirable to tie the wall to the
+rock. This was done by drilling into the rock holes from 6 to 15 ft. in
+depth, and grouting into each hole a 1-1/2-in. rod having a split end and a
+steel wedge. The outer end of each rod was fitted with a 12 by 12 by
+1/2-in. plate and a nut, and extended into the wall, thus tying the
+concrete securely to the rock. The drains being 6 ft. from center to
+center, the tie-rods were placed midway between them, and 6 ft., from
+center to center, vertically and horizontally. Fig. 8 shows the arrangement
+of these rods and drains. Around the Express Building site, just west of
+Ninth Avenue, on the south side of the work, the bridge seat was omitted,
+and the face wall was designed 2 ft. thick from top to bottom. The batter
+on the 31st Street wall was made variable, the top and bottom being
+constant distances from the center line and on different grades.
+
+The retaining walls were water-proofed with three layers of felt and
+coal-tar pitch, which was protected by 4 in. of brick masonry. A 6-in.
+vitrified drain pipe was laid along the back of the wall, with the joints
+open on the lower half, and this was covered with 1 ft. of broken stone and
+sand before any back-fill was placed on it.
+
+The arrangement of the drains was as follows: The 6-in. drain back of the
+retaining wall was connected with one of the box drains in the rear of the
+face wall by a cast-iron pipe or wooden box every 24 ft., and this ran
+through the base of the retaining wall. Midway between these pipes, a
+connection was made at the bridge seat between the drain in the rear of the
+face wall and the gutter formed at the rear of the bridge seat to carry off
+rain-water coming down the face of the wall above. All the box drains,
+except those connected with the drains back of the retaining wall, were
+sealed at the elevation of the base of the retaining wall, as noted
+previously.
+
+The specifications required vitrified pipe to be laid through the retaining
+wall, but, owing to the difficulty of holding the short lengths of pipe in
+place during the laying of wet concrete, they were dispensed with, and
+either iron pipes or wooden boxes were used.
+
+_Tie-Rods._--When the excavation on the sides had been completed, movable
+drilling platforms were erected, as shown by Fig. 4, Plate L. The holes
+were drilled on a pitch of 2 in. per ft. with the horizontal. The depths of
+the holes were decided by the engineer, and were on the basis of a minimum
+depth of 5 ft. in perfect rock; the character of the rock, therefore, and
+the presence of seams, determined the depths of the holes. Each hole was
+partly filled with grout, and the rod, with the steel wedge in the split
+end, was inserted and driven with a sledge so that the wedge, striking the
+bottom of the hole first, would cause the split end of the rod to open.
+Each hole was then entirely filled with neat cement grout.
+
+_Box Drains._--Various methods of forming the box drains were considered,
+such as using half-tile drains, or a metal form, or a collapsible form
+which could be withdrawn, but it was finally decided to build boxes in
+which the side toward the rock was open and the joints in the boxes and
+against the rock were plastered with cement mortar. These boxes were left
+in place. Fig. 1, Plate LI, shows the tie-rods and box drains in place, and
+holes being cut near the bottom of the drains for the pipes leading through
+the wall.
+
+_Forms._--Fig. 1, Plate LI, shows the form used on the south side of the
+work. The materials were of good quality, and the form, which was about 50
+ft. long, was used to build twelve sections, or about 600 ft. of wall. The
+form was tied in at the top and bottom by cables attached to rods drilled
+into the rock, and it was thought that, with the trusses to stiffen the
+middle section of the form, it would not be necessary to use raker braces
+against it. This would have been desirable, as the placing of the raker
+braces took considerable time. It was found, however, that the form was not
+sufficiently rigid, as it bulged at the middle section and could not be
+held by the trusses. Two or three sets of raker braces, about 12 ft. apart,
+were used, and in addition, rods with turnbuckles were placed through the
+form and fastened to the tie-rods, and thus the form was held in place
+successfully. On the forms built later, the trusses were omitted, and raker
+braces, about every 6 ft., were used. The rods which screwed into the
+turnbuckles were removed before the form was moved. The photograph, Fig. 4,
+Plate LII, was taken inside the concrete form for the lower face wall on
+the north side, and shows the drains leading through the wall, the
+turnbuckles attached to the tie-rods, the cables attached to rods in the
+rock, and the braces to keep the form from coming in; these braces, of
+course, were removed as the concrete came up. The form was built low and
+wedged up into position. After a section of concrete had set sufficiently,
+the wedges were knocked out, the form was lowered and moved from the wall,
+and was then moved along the lowest waling piece by block and tackle to its
+new position.
+
+Fig. 4, Plate L, shows the forms used on the north side of the work.
+
+A section, 1 ft. square, at the top of the bridge seat of the lower face
+wall, was left out, so that the bottom of the form for the upper face wall
+could be braced against it. The top of this form was tied by cables
+attached to rods in the rock and by rods with turnbuckles running from back
+to front of the form; braces were also put in from the back of the
+retaining wall form to the walls of buildings along the property lines,
+when this could be done. The middle section of the form was held by rods
+with turnbuckles which passed through the form and were fastened to each of
+the tie-rods drilled into the rock, as was also done in the case of the
+lower face wall. It was generally possible to hold the form to true
+position in this manner, but occasionally it had a tendency to bulge; when
+this occurred, the rods leading through the form and fastened to the
+tie-rods were tightened up, the placing of the concrete was slowed up, and
+no serious bulging occurred.
+
+Bulkheads at the ends of the sections were built of rough planking securely
+braced to the rock, except that a planed board was laid up against the face
+of the form to make a straight joint. At the end of each section a V was
+formed, as shown by Fig. 1, Plate LI. At all corners, a "return," or
+portion of the wall running at right angles, was built, and no section of
+wall was stopped at a corner.
+
+_Filling Forms of Lower Face Walls._--A temporary trestle was erected above
+the elevation of the bridge seat, and a track, leading from the mixer to
+the form to be filled, was laid on it. At the commencement of each section
+a layer of mortar (1 part of cement to 2-1/2 parts of sand) was deposited
+on the bottom. A 1:3:6 mixture of concrete was used; it was run from the
+mixer into dump-cars and deposited in the form through chutes, three of
+which were provided for each 50-ft. section, the average length. The
+concrete was mixed wet, and was not rammed; the stone was spaded back from
+the face, and no facing mixture or facing diaphragms were used. Work on
+each section was continued day and night without any intermission from the
+time of commencement to the time of completion. At frequent intervals the
+box drains were washed out thoroughly with a hose, in order to prevent them
+from clogging up with grout.
+
+[Illustration: PLATE LI, FIG. 1.--TW 66, P.N.Y. & L.I.R.R. Terminal Station
+West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17,
+08.]
+
+[Illustration: PLATE LI, FIG. 2.]
+
+[Illustration: PLATE LI, FIG. 3.--P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy.
+West. Disposal trestle just before demolition. View of South side showing
+chutes. Jan. 21, 09.]
+
+[Illustration: PLATE LI, FIG. 4.--A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy.
+West & Oj. View across North River on line of Tunnels, looking from New
+York to New Jersey. Feb. 9, 07.]
+
+In the first few sections of wall, the form was filled to within 1 in. of
+the top of the bridge seat and allowed to set for about 2 hours; it was
+then finished to the proper elevation with a plaster of 1 part of cement to
+1 part of sand. This did not prove satisfactory, as there were indications
+of checking and cracking, and, later, the form was filled to the required
+elevation and the surface floated. The form was allowed to remain in place
+for from 18 to 24 hours, depending on the weather. In most cases,
+immediately after the form had been moved, a scaffold was erected against
+the face of the wall, and the face was wet and thoroughly rubbed, first
+with a wooden float and then with a cement brick, until the surface was
+smooth and uniform.
+
+The section 1 ft. square at the top of the bridge seat, which was left out
+in order to brace the bottom of the form for the upper face wall, was
+filled in after the walls had been completed. The old concrete was very
+thoroughly cleaned before the new concrete was placed on it, and a gutter
+was formed at the rear connecting with the box drains back of the wall to
+carry off rain-water coming down the face of the upper walls.
+
+In hot weather the walls were thoroughly wetted down several times a day
+for several days after the form had been removed.
+
+_Upper Face and Retaining Wall._--In cases where the top of the retaining
+wall was at a higher elevation than the mixer, it was necessary to raise
+the concrete in a bucket with a derrick, and dump it into cars on the
+trestle above the top of the coping. Concrete was deposited through chutes,
+as in the lower face wall, continuously from the bottom of the face wall to
+the top of the retaining wall. At the commencement of each section of the
+retaining wall a layer of mortar was put on the rock. A 1:2:3 mixture of
+concrete was used in the face wall, and a 1:3:6 mixture in the retaining
+wall.
+
+As the face walls were so thin, the number of batches of concrete per hour
+was reduced, for the form filled so rapidly that the concrete, before it
+set, exerted an excessive pressure against the form, and this tended to
+make it bulge. The proper rate at which to place the concrete behind a form
+50 ft. long, with a wall 2 ft. thick, was found to be about fifteen 1/2-yd.
+batches per hour.
+
+_Cracks in Walls and Longitudinal Reinforcement._--Before the concrete
+walls were started, the contractor suggested using forms 100 ft. long and
+building the walls in sections of that length; it was decided, however, to
+limit the length to 50 ft.
+
+The south walls, in sections approximately 50 ft. long, were built first,
+starting at Tenth Avenue and extending for about 500 ft. Soon after the
+forms were removed, irregular cracks appeared in the walls between the
+joints in practically every section. It was thought that these cracks might
+be due to the wall being very thin and being held at the back by the
+tie-rods; there was also quite a material change in the section of the wall
+at each drainage box. Although it was admitted that these cracks would have
+no effect on the stability of the wall, it was thought that, for appearance
+sake, it would be desirable to prevent or control them, if possible. The
+first method suggested was to shorten the sections to 25 ft., which would
+give an expansion and contraction joint every 25 ft., it being thought that
+sections of this length would not crack between the joints. This, however,
+was not considered desirable. An effort was then made to prevent cracks in
+a section of wall, about 46 ft. long, on the south side, by using
+longitudinal reinforcement. In the lower and upper face walls, 3/4-in.
+square twisted steel rods were placed longitudinally about 4 in. in from
+the face and about 1 ft. 4 in. apart vertically. The sections of these
+walls were finished on April 10th, and May 5th, 1909, respectively. At
+present there are no indications of cracks in these sections, and they are
+practically the only ones in the south walls which do not show irregular
+cracks.
+
+It was decided, however, that, inasmuch as the cracks did not affect the
+stability of the walls, the increased cost of thus reinforcing the
+remaining walls was not warranted. An effort to control the cracks was made
+by placing corrugated-iron diaphragms in the form, dividing each 50-ft.
+section into three parts. The diaphragms were 1 ft. wide, and were placed
+with the outer edge 1 in. in from the face of the wall, but in the copings
+they were omitted. The purpose of these diaphragms was to provide weak
+sections in the walls, so that if there was any tendency to crack it would
+occur along the line of the diaphragms. Corrugated iron was used for the
+diaphragms instead of sheet iron as it was more easily maintained in a
+vertical position. The general arrangement of the diaphragms is shown on
+Fig. 4, Plate LII. The results obtained by using diaphragms have been quite
+satisfactory, and cracks approximately straight and vertical have usually
+appeared opposite the diaphragms soon after the forms were removed.
+Diaphragms were used on all the remaining walls, with the exception of
+those between Stations 187 + 07 and 188 + 83 on the north side, where the
+rock was of poor character and bad slides had occurred. Between these
+points, in order to strengthen the wall, twisted steel rods, 1 in. square,
+were placed longitudinally, 6 in. in from the face of the wall and 2 ft.
+apart vertically, between Elevations 295 and 335.
+
+[Illustration: PLATE LII, FIG. 1.--GIRDERS UNDER 9TH AVENUE ELEVATED
+RAILROAD.]
+
+[Illustration: PLATE LII, FIG. 2.--TW 100. P.T. & T.R.R. Co. Terminal
+Station West. Showing excavation of completion of South abutment 9th Ave.
+and method of Supporting Elevated Railway Column 488. July 21, 09.]
+
+[Illustration: PLATE LII, FIG. 3.--TW 31. P.T. & T.R.R. Co. Terminal
+Station West. View showing excavation 9th and 10th Avenues South of 32nd
+St. looking West from Sta. 184. Aug. 17, 07.]
+
+[Illustration: PLATE LII, FIG. 4.--TW 101. P.T. & T.R.R. Co. Terminal
+Station West. Inside of concrete form for lower-face wall, showing drains,
+tie rods, diaphragms and methods employed for tying in the form in addition
+to braces outside. July 21, 09.]
+
+_Tenth Avenue Portal._--The design of the Tenth Avenue Portal is shown on
+Fig. 9. The stone selected came from the Millstone Granite Company's
+Quarries, Millstone Point, Conn., and is a close-grained granite. Fig. 2,
+Plate LI, shows the completed portal.
+
+Practically all the stone cutting was done at the quarry, but certain
+stones in each course were sent long and were cut on the ground, in order
+to make proper closures. Drains were left behind the portal around the back
+of each arch, leading down to the bottom, and through the concrete base at
+each side of the portal and in the central core-wall; all these drains have
+been discharging water.
+
+_Power-House._--The old church at No. 236 West 34th Street, between Seventh
+and Eighth Avenues, was turned over to the New York Contracting
+Company-Pennsylvania Terminal for a power-house to supply compressed air
+for use on the Terminal Station work between Seventh and Ninth Avenues and
+the work below sub-grade as well as that on the Terminal Station-West. Four
+straight-line compressors and one cross-compound Corliss compressor were
+installed, the steam being supplied by three Stirling boilers. Three
+electrically-driven air compressors, using current at 6,600 volts, were
+also installed, and the total capacity of the power-house was about 19,000
+cu. ft. of free air per minute compressed to 90 lb. per sq. in.
+
+_Disposal Pier._--The disposal pier (old No. 62 and new No. 72), at the
+foot of West 32d Street, North River, was leased by the Pennsylvania
+Railroad Company. The entire pier, with the exception of the piles, was
+taken down, and the piles which would be in the path of the proposed tunnel
+were withdrawn prior to the building of the tunnels and the construction of
+the pier for disposal purposes. Subsequent to the driving of the tunnels
+there was a considerable settlement in the pier, especially noticeable at
+the telphers, and finally these had to be abandoned on this account. Fig.
+3, Plate LI, shows the chutes through which the earth was dumped on the
+decks of the scows to form a padding on which to dump the heavier rock.
+Fig. 4, Plate LI, shows the derricks at the end of the pier. These were
+used, not only for loading heavy stones and skips, but also with a
+clam-shell bucket for bringing in broken stone and sand for use in the
+work. Large quantities of pipe, conduits, brick, etc., were also brought to
+this pier for use on the work.
+
+[Illustration: FIG. 9. (Full page image)
+
+PORTAL, RETAINING AND FACE WALLS, TENTH AVENUE]
+
+
+ORGANIZATION OF ENGINEERING FORCE IN FIELD.
+
+The design and execution of the work were under the direction of Charles M.
+Jacobs, M. Am. Soc. C.E., Chief Engineer, and James Forgie, M. Am. Soc.
+C.E., Chief Assistant Engineer. The writer acted as Resident Engineer.
+
+[Illustration: Fig. 10.]
+
+The general organization of the engineering force in the field is shown by
+the diagram, Fig. 10.
+
+The position of Assistant Engineer, in responsible charge of Construction
+and Records, has been filled in turn by Messrs. A.W. Gill, N.C. McNeil,
+Jun. Am. Soc. C.E., and W.S. Greene, Assoc. M. Am. Soc. C.E.
+
+Messrs. A.P. Combes and T.B. Brogan have acted as Chief Inspector and Night
+Inspector, respectively, in charge of outside work during the entire
+carrying out of the contract.
+
+Base lines had been established on Ninth and Tenth Avenues for the Terminal
+work east of Ninth Avenue and for the Tunnel work west of Tenth Avenue,
+and these lines, together with bench-marks similarly established, were used
+in laying out the Terminal Station-West work.
+
+Prior to the commencement of the work, elevations were taken on the surface
+at 10-ft. intervals, and elevations of the rock surface were taken on these
+points as the rock was uncovered. Cross-sections were made and used in
+computing the progress and final estimates.
+
+Very careful records were kept of labor, materials, derrick performances,
+steam-shovel performances, quantity of dynamite used, etc., and, in
+addition, a diary was kept giving a description of the work and materials
+used each day; various tables and diagrams were also prepared.
+
+A daily report was sent to the Chief Office showing the quantities of
+excavation removed and concrete built, the force in the field, the plant at
+work, etc., during the previous day. At the end of each month a description
+of the work done during that month, with quantities, force of men employed,
+percentages of work done, etc., was sent to the Chief Office. Two diagrams,
+showing cross-sections and contours of the excavation done and the progress
+of the concrete walls, were also sent.
+
+
+COST ACCOUNT.
+
+From the records of labor and material obtained in the field, and from
+estimated charges for administration and power, an estimate was made of the
+cost to the contractor for doing various classes of work. It was necessary
+to estimate the administration and power charges, as the contractor's
+organization and power-house were also controlling and supplying power to
+the Terminal Station work east of Ninth Avenue and also the work below
+sub-grade. The labor and material charges in the field were placed directly
+against the class of work on which they were used and the administration
+and general charges (which included superintendence, lighting, etc.) were
+apportioned to the various classes of work in proportion to the value of
+the labor done.
+
+
+STATISTICS.
+
+The total weight of the structural steel used during the underpinning of
+Ninth Avenue was 1,475,000 lb.
+
+The total weight supported during the work under Ninth Avenue was about
+5,000 tons.
+
+\U$1\EThe average daily traffic over the Ninth Avenue Elevated Railway was
+90,000 passengers, and, during the progress of the excavation and
+underpinning, about 100,000,000 passengers were carried over that
+structure.
+
+The total excavation was 521,000 cu. yd., of which 87% was solid rock.
+
+The average drill performance was about 33 lin. ft. per 8-hour shift.
+
+The average number of cubic yards of excavation per drill shift was 13.9.
+
+The average number of feet of drilling per cubic yard of excavation was
+about 2.4.
+
+The average excavation per pound of dynamite was 2.2 cu. yd.
+
+The average amount of excavation per derrick shift of ten hours, 87% of the
+excavation being rock, was 50 cu. yd.
+
+The average derrick force per shift, including only foreman and laborers,
+was 13 men.
+
+The salaries of the engineering staff in the field and the expenses of
+equipping and maintaining the field office amounted to 2.8% of the cost of
+the work executed, 2.7% being for engineering salaries alone.
+
+FOOTNOTES:
+
+[Footnote A: Presented at the meeting of April 6th, 1910.]
+
+
+
+
+
+End of the Project Gutenberg EBook of Transactions of the American Society
+of Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
+*** END OF THIS PROJECT GUTENBERG EBOOK SOCIETY OF CIVIL ENGINEERS ***
+
+***** This file should be named 17302-8.txt or 17302-8.zip *****
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+      The Project Gutenberg eBook of THE NEW YORK TUNNEL EXTENSION OF THE
+PENNSYLVANIA RAILROAD, by B.F. Cresson, Jr.
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+<pre>
+
+The Project Gutenberg EBook of Transactions of the American Society of
+Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910
+       The New York Tunnel Extension of the Pennsylvania Railroad
+              The Terminal Station - West
+
+Author: B.F.  Cresson, Jr
+
+Release Date: December 13, 2005 [EBook #17302]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SOCIETY OF CIVIL ENGINEERS ***
+
+
+
+
+Produced by Juliet Sutherland, Sigal Alon and the Online
+Distributed Proofreading Team at https://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+
+<p><span class='pagenum'><a name="Page_303" id="Page_303">[303]</a></span></p>
+
+
+<h2>AMERICAN SOCIETY OF CIVIL ENGINEERS</h2>
+
+<h3>INSTITUTED 1852</h3>
+
+<hr style="width: 45%;" />
+
+<h1>TRANSACTIONS</h1>
+
+<hr style="width: 35%;" />
+
+<h3>Paper No. 1156</h3>
+
+<hr style="width: 45%;" />
+
+<h1>THE NEW YORK TUNNEL EXTENSION OF THE
+PENNSYLVANIA RAILROAD.</h1>
+
+<h1>THE TERMINAL STATION-WEST.<a name="FNanchor_A_1" id="FNanchor_A_1"></a><a href="#Footnote_A_1" class="fnanchor">[A]</a></h1>
+
+<h2><span class="smcap">By B.F. Cresson, Jr., M. Am. Soc. C.E.</span></h2>
+
+<hr style="width: 45%;" />
+
+<p><i>Location of Work.</i>&mdash;The area covered by the work of the Terminal
+Station-West is bounded as follows: By the east line of Ninth
+Avenue; by the south side of 31st Street to a point about 200 ft.
+west of Ninth Avenue; by a line running parallel to Ninth Avenue
+and about 200 ft. therefrom, from the south side of 31st Street to
+the boundary line between the 31st and 32d Street properties; by this
+line to the east line of Tenth Avenue; by the east line of Tenth
+Avenue to the boundary line between the 32d and 33d Street properties;
+by this line to the east line of Ninth Avenue. The area is approximately
+6.3 acres.</p>
+
+<p><i>House-Wrecking.</i>&mdash;The property between Ninth and Tenth Avenues
+was covered with buildings, 94 in number, used as dwelling and apartment
+houses and church properties, and it was necessary to remove
+these before starting the construction. Most of the property was bought
+outright by the Railroad Company, but in some cases condemnation
+proceedings had to be instituted in order to acquire possession. In the
+case of the property of the Church of St. Michael, fronting on Ninth
+Avenue, 31st and 32d Streets, the Railroad Company agreed to purchase
+a plot of land on the south side of 34th Street, west of Ninth<span class='pagenum'><a name="Page_304" id="Page_304">[304]</a></span>
+Avenue, and to erect thereon a church, rectory, convent, and school,
+to the satisfaction of the Church of St. Michael, to hand over these
+buildings in a completed condition, and to pay the cost of moving
+from the old to the new buildings, before the old properties would be
+turned over to the Railroad Company.</p>
+
+<p>The house-wrecking was done by well-known companies under contract
+with the Railroad Company. These companies took down the
+buildings and removed all the materials as far as to the level of the
+adjacent sidewalks. The building materials became the property of
+the contractors, who usually paid the Railroad Company for the
+privilege of doing the house-wrecking. The work was done between
+April and August, 1906, but the buildings of the Church of St. Michael
+were torn down between June and August, 1907.</p>
+
+<p>The bricks were cleaned and sold directly from the site, as were
+practically all the fixtures in the buildings. The stone fronts were
+broken up and left on the premises. Some of the beams were sold on
+the premises, but most of them were sent to the storage yards. Some
+of the lath and smaller timber was sold for firewood, but most of it
+was given away or burned on the premises.</p>
+
+<p><i>Contracts and Agreements.</i>&mdash;The main contract, awarded to the
+New York Contracting Company-Pennsylvania Terminal on April
+28th, 1906, included about 502,000 cu. yd. of excavation (about 90%
+being rock), 17,820 cu. yd. of concrete walls, 1,320,000 lb. of structural
+steel, 638,000 ft., B.M., of framed timber, etc., etc.</p>
+
+<p>This contract was divided into two parts: "Work In and Under
+Ninth Avenue" and "Work Between Ninth and Tenth Avenues," and
+unit prices were quoted for the various classes of work in each of
+these divisions. The prices quoted for excavation included placing
+the material on scows supplied by the Railroad Company at the pier
+at the foot of West 32d Street, on the North River; there was a clause
+in the contract, however, by which the contractor could be required to
+make complete disposal of all excavated material at an additional unit
+price, and this clause was enforced on January 1st, 1909, when about
+94% of the excavation had been done.</p>
+
+<p>For the purpose of disposing of the excavated material in the
+easterly portion of the Terminal, the New York Contracting Company-Pennsylvania
+Terminal had excavated under Ninth Avenue a cut which
+came to the grade of 32d Street about midway between Ninth and<span class='pagenum'><a name="Page_305" id="Page_305">[305]</a></span>
+Tenth Avenues, and a trestle was constructed from this point over
+Tenth Avenue and thence to the disposal pier at the foot of West 32d
+Street.</p>
+
+<p>On May 11th, 1906, the work of excavation was commenced on the
+east side of Ninth Avenue, and on July 9th, 1906, on the south side
+of 31st Street, between Ninth and Tenth Avenues. From the beginning,
+the excavation was carried on by day and night shifts, except
+on Sundays and holidays, until January, 1909, except that during the
+period from November, 1907, to October, 1908, the night shift was
+discontinued.</p>
+
+<p><i>Geology.</i>&mdash;The rock encountered may be classed as "gneiss"; its
+character varied from granite to mica schist. It was made up of
+quartz, feldspar, and mica, and there were also some isolated specimens
+of pyrites, hornblend, tourmaline, and serpentine. On the south side
+of the work, just west of Ninth Avenue, there were excellent examples
+of "contortions" of veins of quartz in the darker rock. On the east
+side of Ninth Avenue, near the north end of the work, glacial marks
+were found on the rock surface. The general direction of the stratification
+was north 5&deg; west, and the general incline about 60&deg; with the
+horizontal. As a rule, the rock broke sharply along the line of stratification.
+On the south side it broke better than on the north side, where
+it was usually softer and more likely to slide; and this, together with
+the fact that in winter it was subject to alternate freezing and thawing
+and in summer to the direct rays of the sun, made it rather difficult to
+get a good foundation for the retaining walls.</p>
+
+
+<p class="sectionh">Work In and Under Ninth Avenue.</p>
+
+<p><i>General Description.</i>&mdash;The work involved the excavation of about
+375 ft. of the full width of Ninth Avenue to an average depth of
+about 58 ft., and the construction over this area of a steel viaduct, the
+deck of which was about 24 ft. below the surface, for the ultimate
+support of the Ninth Avenue structures.</p>
+
+<p>The following estimated quantities appear in the contract: Excavation
+of rock, 72,600 cu. yd.; excavation of all materials except rock,
+9,300 cu. yd.; concrete (1:3:6) in abutments, etc., 1,680 cu. yd.;
+timber, 504,000 ft., B.M.; structural steel, 1,320,000 lb., etc.</p>
+
+<p>While this excavation was being done it was necessary to support
+and maintain the three-track elevated railway structure of the Interborough<span class='pagenum'><a name="Page_306" id="Page_306">[306]</a></span>
+Rapid Transit Company, of which 18 columns, or a length of
+about 340 ft., were affected, the two-track surface railway structure
+of the New York City Railway Company, and various pipes, sewers,
+and conduits, and to maintain all surface vehicular and pedestrian
+traffic. All structures were left in place with the exception of the
+pipes, most of which were temporarily cut out. The 48-in. brick sewer
+in the center of Ninth Avenue was broken, and the sewage was pumped
+across the excavation through a smaller pipe.</p>
+
+<p>The general method adopted was as follows: The east and west
+sides of the avenue were closed, vehicular traffic was turned into the
+center, and a trestle for pedestrians was constructed west of the westerly
+elevated railway columns. All structures were then supported
+on transverse girders, running across the avenue, below the surface,
+and these rested on concrete piers on the central rock core. The sides
+of the avenue were then excavated to sub-grade, and the permanent
+steel viaduct was erected on both sides of the avenue as close as
+possible to the central rock core. The weight of all structures was
+then transferred to the permanent steel viaduct, erected on the sides
+of the avenue, by timber bents under the transverse girders resting on
+the permanent steel viaduct, and all weight was thus taken off the
+central rock core. This core was then excavated to sub-grade, the
+permanent viaduct was completed, and all structures were placed on
+its deck, using concrete piers and timber bents.</p>
+
+<p>The design and erection of the permanent steel viaduct and the
+permanent foundations on its deck were done under another contract,
+apart from the North River Division work, and are not described in
+this paper.</p>
+
+<p><i>Elevated Railway Structure of the Interborough Rapid Transit
+Company.</i>&mdash;The Ninth Avenue Elevated Railway was built between
+1877 and 1880 as a two-track structure, the design being such as to
+permit a third or central track to be added later, and this was built
+in 1894. It is supported on columns under the outside tracks, about
+43 ft. from center to center longitudinally and 22 ft. 3 in. from center
+to center transversely, the central track being carried by transverse
+girders between the columns.</p>
+
+<p>The columns carrying the structure are of fan top design, with the
+points of bearing near the extremities at the top; each of the outside
+tracks is supported on two longitudinal latticed girders and the central
+<span class='pagenum'><a name="Page_307" id="Page_307">[307]</a></span>track on two plate girders; between the columns, transverse girders
+are spliced to the outside track cross-frames, and carry the central
+track system. It was not thought desirable to put brackets on the
+columns near the street level to support the structure temporarily, and,
+as there is an expansion joint at each column, and as the transverse
+girders carrying the central track system are not rigidly attached to
+the longitudinal girders carrying the outside tracks, the central track
+could not be supported by supporting the outside tracks; therefore,
+independent supports for each track, in the form of overhead girders,
+had to be provided. The columns rest on brick piers, each having four
+2-in. anchor-bolts. The brick foundations on the west side are wide
+in order to allow a 24-in. water main to pass directly beneath the
+columns. The foundations are usually on rock.</p>
+
+<div class="figcenter" style="width: 590px;">
+<img id="plate47_fig1" src="images/p47f1.jpg" width="590" height="465"
+alt="Plate XLVII, Fig. 1.&mdash; TW 4, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of 9th Ave. looking Northwest from 32nd Street, prior to commencement of work. April 23, 06."
+title="Plate XLVII, Fig. 1.&mdash; TW 4, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of 9th Ave. looking Northwest from 32nd Street, prior to commencement of work. April 23, 06." />
+<span class="caption">Plate XLVII, Fig. 1.&mdash; TW 4, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of 9th Ave. looking Northwest from 32nd Street, prior to commencement of work. April 23, 06.</span>
+</div>
+
+<div class="figcenter" style="width: 577px;">
+<img id="plate47_fig2" src="images/p47f2.jpg" width="577" height="449"
+alt="Plate XLVII, Fig. 2.&mdash; TW 17, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of East side of 9th Ave. looking North from a point 100 feet south of 33rd St. showing condition of work. July 23, 06."
+title="Plate XLVII, Fig. 2.&mdash; TW 17, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of East side of 9th Ave. looking North from a point 100 feet south of 33rd St. showing condition of work. July 23, 06." />
+<span class="caption">Plate XLVII, Fig. 2.&mdash; TW 17, P.N.Y. &amp; L.I.R.R. Terminal Station West. View of East side of 9th
+Ave. looking North from a point 100 feet south of 33rd St. showing condition of work. July 23, 06.</span>
+</div>
+
+<div class="figcenter" style="width: 578px;">
+<img id="plate47_fig3" src="images/p47f3.jpg" width="578" height="448"
+alt="Plate XLVII, Fig. 3.&mdash; TW 25, P.N.Y. &amp; L.I.R.R. Terminal Station West. View showing permanent and temporary supports of 9th Ave. Structures, looking Northwest from 31st. St. April 24, 07."
+ title="Plate XLVII, Fig. 3.&mdash; TW 25, P.N.Y. &amp; L.I.R.R. Terminal Station West. View showing permanent and temporary supports of 9th Ave. Structures, looking Northwest from 31st. St. April 24, 07." />
+<span class="caption">Plate XLVII, Fig. 3.&mdash; TW 25, P.N.Y. &amp; L.I.R.R. Terminal Station West. View showing permanent and temporary supports of 9th Ave. Structures, looking Northwest from 31st. St. April 24, 07.</span>
+</div>
+
+<div class="figcenter" style="width: 577px;">
+<img id="plate47_fig4" src="images/p47f4.jpg" width="577" height="450"
+alt="Plate XLVII, Fig. 4.&mdash; TW 28, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Avenue, North of 32nd St. looking West, showing rock excavation and supports of 9th Avenue structures. Aug. 17, 07."
+title="Plate XLVII, Fig. 4.&mdash; TW 28, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Avenue, North of 32nd St. looking West, showing rock excavation and supports of 9th Avenue structures. Aug. 17, 07." />
+<span class="caption">Plate XLVII, Fig. 4.&mdash; TW 28, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Avenue, North of 32nd St. looking West, showing rock excavation and supports of 9th Avenue structures. Aug. 17, 07.</span>
+</div>
+
+<p><a href="#plate47_fig1">Fig. 1, Plate XLVII</a>, shows the elevated railway structure and the
+street surface prior to the commencement of the work.</p>
+
+<p>The east track is used for north-bound local trains, the west track
+for south-bound local trains, and the central track for south-bound
+express trains between 7 and 9.30 <span class="smcap">a.m.</span> and for north-bound express
+trains between 2.30 and 7 <span class="smcap">p.m.</span> It is said that an average of 90,000
+passengers are carried over this structure every 24 hours.</p>
+
+<p><i>Surface Railway Structure of the New York City Railway Company.</i>&mdash;This
+is an electric surface railway of the ordinary type, the
+rail and slot being bedded in concrete, with cast-iron yokes every 5 ft.
+There are manholes every 100 ft., and cleaning-out holes every 15 ft.
+Power conduits are bedded in the concrete on the east side of the
+east track.</p>
+
+<p><i>Forty-eight-Inch Brick Sewer.</i>&mdash;This sewer was in the center of
+Ninth Avenue, with the invert about 12 ft. below the surface, and
+manholes about 100 ft. apart, and had to be abandoned in this position
+to allow the transverse girders to be put in place to carry all structures
+while the excavation was being done.</p>
+
+<p><i>Twenty-four-Inch Cast-Iron Water Main.</i>&mdash;This water main was
+laid under the west elevated railway columns, with its top about 3 ft.
+below the surface, a space being left for it in the brick foundations,
+and a large column base casting being used to span it. Valves were
+installed, one north of 33d Street and one south of 31st Street, prior
+to excavating near the pipe, so that if it was broken the water could
+be shut off promptly.</p>
+
+<p><span class='pagenum'><a name="Page_308" id="Page_308">[308]</a></span></p><p><i>Street Surface.</i>&mdash;It was the original intention to close and excavate
+the east side of the avenue and to erect there a street-traffic trestle
+before closing the west side, but, at the contractor's request, both sides
+were closed, and all vehicular traffic was turned into the center. A
+light trestle on the west side of the avenue provided for pedestrian
+traffic.</p>
+
+<p><i>Other Sub-surface Structures.</i>&mdash;There were various gas mains,
+water mains, electric conduits, manholes, hydrants, etc., in the avenue,
+and most of these were cut out temporarily, at the contractor's request,
+to be replaced subsequently.</p>
+
+<p><i>Supports for Elevated Railway Structure.</i>&mdash;As stated previously,
+the central track had to be supported independently.</p>
+
+<p>The overhead girders, known as girders "B", were therefore designed
+as shown on <a href="#fig_01">Fig. 1</a>, and put in place as shown on <a href="#fig_02">Figs. 2</a> and <a href="#fig_03">3</a>.
+The outside tracks were blocked directly on these girders, and the
+central track was supported by blocking up the transverse girders on
+I-beams placed between the girders "B"; and no blocking was placed
+between the girders "B" and the longitudinal girders carrying the
+central track. The weight on each column was assumed to be
+172,000 lb.</p>
+
+
+<div id="Page_309" class="figcenter" style="width: 541px;">
+<a href ="images/fig01.png">
+<img id="fig_01" src="images/fig01tn.png" width="541" height="361" alt="DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES" title="DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES" />
+<span class="caption">Fig. 1.</span> (full page image)<br />
+DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES
+</a>
+</div>
+
+<p><i>Supports for Surface Railway Structure.</i>&mdash;A uniform load of
+3,000 lb. per lin. ft. of single track, with the weight of a car at
+39,000 lb., was assumed. Several feet of earth, between the structure
+and the rock, were mined out, and the structure was supported on
+I-beams and posts, and ultimately on the transverse girders by using
+timber bents under the I-beams, as shown on <a href="#fig_03">Fig. 3</a>.</p>
+
+<p><i>Water Mains and Sewer.</i>&mdash;Cradles were designed for the support
+of the 48-in. and 24-in. water mains, resting on the transverse girders,
+and the 48-in. cast-iron sewer on the east side of the avenue was carried
+on I-beams bracketed to the ends of the transverse girders, as shown
+on <a href="#fig_01">Figs. 1</a> and <a href="#fig_02">2</a>.</p>
+
+<div id="Page_311" class="figcenter" style="width: 510px;">
+<a href ="images/fig02.png">
+<img id="fig_02" src="images/fig02tn.png" width="510" height="354" alt="METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE" title="METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE" />
+<span class="caption">Fig. 2.</span> (full page image)<br />
+METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE
+</a>
+</div>
+
+<div id="Page_312" class="figcenter" style="width: 529px;">
+<a href ="images/fig03.png">
+<img id="fig_03" src="images/fig03tn.png" width="529" height="363" alt="METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO." title="METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO." />
+<span class="caption">Fig. 3.</span> (full page image)<br />
+METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO.
+</a>
+</div>
+
+<p><i>Girders "C."</i>&mdash;The transverse girders below the street surface,
+referred to above, were known as girders "C," and they were put in
+place at first resting on concrete piers on the central core; the weight
+of all structures was placed on them while the sides of the avenue
+were being excavated, and the sides of the viaduct were being built.
+The ends of these girders were then picked up on the sides of the
+viaduct, and, spanning the central rock core, carried all structures
+<span class='pagenum'><a name="Page_310" id="Page_310">[310]</a></span>while the core was being excavated and the viaduct completed. New
+foundations were then placed on the deck of the viaduct to carry all
+structures.</p>
+
+<p>Fifty-four of these girders were required, each weighing about
+19,000 lb. The bents carrying the ends of these girders on the sides
+of the viaduct are shown on <a href="#fig_02">Fig. 2</a>. They were of long-leaf yellow
+pine. These girders were located so that a cradle could be laid on them
+east of the elevated railway structure to carry a proposed 48-in. cast-iron
+water main.</p>
+
+<p><i>Girders "B."</i>&mdash;Eighteen of these girders were required, each weighing
+about 6,000 lb. The timber bents supporting these girders, shown
+on <a href="#fig_02">Fig. 2</a>, were of long-leaf yellow pine.</p>
+
+<p>The total weight, including the elevated railway structure, surface
+railway structure, pipes, etc., supported during the work, amounted to
+about 5,000 tons.</p>
+
+<p><i>Details of the Work.</i>&mdash;The method in general is shown on <a href="#fig_04">Figs.
+4</a> and <a href="#fig_05">5</a>. At first the east side of the avenue was closed and excavated
+down to rock, the earth was mined out under alternate yokes of the
+surface railway structure, and temporary posts were placed under the
+yokes to support the structure while the remainder of the earth was
+being removed. Then needle-beams and posts were placed under
+each yoke. The concrete forming the track structure was then enclosed
+with planking to prevent it from cracking and falling. I-beams
+were then placed under the needle-beams carrying the structures, and
+these were carried on posts; they were changed alternately until the
+excavation had been taken out to a depth of about 16 ft. below the
+surface. In placing these I-beams, heavier blocking was used in the
+center of the span than at the ends where the bents would come, to
+prevent the subsidence of the track owing to the sag in the I-beams.
+As much excavation, to a depth of about 20 ft., was taken out adjoining
+the elevated railway foundations as could be done with safety.
+<a href="#plate47_fig2">Fig. 2, Plate XLVII</a>, shows this condition of the work. The 48-in.
+brick sewer was broken, and the sewage was pumped across the
+excavation.</p>
+
+<p>The overhead girders "B" were then put in place, and two of the
+girders "C" were used as temporary shoring girders at each column.
+These, as shown by <a href="#plate47_fig3">Fig. 3, Plate XLVII</a>, were placed parallel to the
+elevated railway, with blocking between them and the girders "B."<span class='pagenum'><a name="Page_315" id="Page_315">[315]</a></span>
+Double bents, independent of each other, were placed under the ends
+of these temporary shoring girders, and these were braced securely
+to prevent possible dislodgment during the removal of the rock. The
+weight of the structure was then taken by jacking up the girders
+near the bents until the column was lifted off the old foundation;
+blocking was put in between the girders and the bents during the jacking,
+so that when the jacks were released the base of the column was
+still clear of the old foundation. One 80-ton jack was used for this
+purpose, and the general method is shown by <a href="#plate52_fig1">Fig. 1, Plate LII</a>.</p>
+
+<div id="Page_313" class="figcenter" style="width: 529px;">
+<a href ="images/fig04.png">
+<img id="fig_04" src="images/fig04tn.png" width="529" height="363" alt="METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES OF THE WORK" title="METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES OF THE WORK" />
+<span class="caption">Fig. 4.</span> (full page image)<br />
+METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES OF THE WORK
+</a>
+</div>
+
+<div id="Page_314" class="figcenter" style="width: 575px;">
+<a href ="images/fig05.png">
+<img id="fig_05" src="images/fig05tn.png" width="575" height="363" alt="METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK" title="METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK" />
+<span class="caption">Fig. 5.</span> (full page image)<br />
+METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK
+</a>
+</div>
+
+<p>Temporary raker braces were placed against the structure to prevent
+lateral movement. Four sets of these temporary shoring girders
+were used in this manner, two sets starting at the north end and two
+sets at about the middle of the work, and these sets were moved south
+as they were released.</p>
+
+<p>The columns being thus supported on temporary shoring girders,
+the old foundations were removed and the excavation was taken down
+to a level about 16 ft. below the surface.</p>
+
+<p>Two sets of three of the girders "C" were then put in place under
+the avenue at each column, each set being placed on four concrete
+piers 6 ft. square with spaces of 4 ft. between them, so that the outside
+of the outside pier would be 18 ft. from the center of the avenue and
+32 ft. from the house line. This is shown on <a href="#fig_05">Fig. 5</a> and on <a href="#plate47_fig3">Fig. 3,
+Plate XLVII</a>. Four small piers were used, as they could be more
+easily removed than one continuous pier. The girders "C" were set to
+line and grade, and the piers were built under them, great care being
+taken to get the concrete well under the girders so as to give a firm
+bearing.</p>
+
+<p>After these girders "C" were in place it was necessary to remove
+the temporary shoring girders before the bents could be erected on
+girders "C" to support girders "B," being in the same plane; and
+provision had to be made to support the structure while this was being
+done. Therefore, double bents were erected directly beneath the
+columns, as shown by <a href="#fig_02">Figs. 2</a>, <a href="#fig_04">4</a>, and <a href="#fig_05">5</a>, and by <a href="#plate47_fig3">Fig. 3, Plate XLVII</a>.
+These were built with their sills resting on the girders "C," and blocking
+was put in between the sills and the rock to carry the full weight
+of the structure. Later, when the weight of the structure was carried
+on the permanent bents, this blocking was knocked out, but the bents
+were left in to carry the weight of the column itself, which was swinging
+<span class='pagenum'><a name="Page_316" id="Page_316">[316]</a></span>more or less from the structure above. The weight of the structure
+was placed on these bents directly beneath the columns by jacking up
+the temporary girders again, putting blocking between the bents and
+the base of the columns, and taking out the blocking which had been
+put in previously under the temporary shoring girders. The 24-in.
+water main was carried over the excavation on cables from the temporary
+shoring girders, except when they were being jacked up, at
+which time posts were placed beneath it.</p>
+
+<p>Anchor-bolts were put in place between the column bases and the
+bents directly beneath, in order to increase the lateral stiffness, and
+raker braces were also used. This having been done, the temporary
+shoring girders were moved south to the next column, where the process
+was repeated. The timber bents, shown in detail by <a href="#fig_02">Fig. 2</a>, were
+then put in place as shown by <a href="#fig_04">Figs. 4</a> and <a href="#fig_05">5</a>, and by <a href="#plate47_fig3">Fig. 3, Plate
+XLVII</a>. These bents were framed as tightly as possible, using generally
+a 20-ton jack, and they were erected simultaneously at each pair
+of columns. The weight was taken on these columns by jacking up
+directly beneath the column base and taking out the blocking between
+this base and the bent directly beneath the column. On releasing the
+jack the weight was transferred to the permanent timber bents, and
+the east and west columns of each pair were transferred on the same
+day. One 80-ton jack was used on the easterly columns and two were
+necessary on the westerly columns, one on each side of the 24-in. water
+main. The raker braces of these permanent bents were not framed as
+tightly as the main posts, in order that the main post should carry
+the entire weight and the raker braces merely steady the structure.</p>
+
+<p>Timber bents were erected on girders "C" to carry the I-beams
+under the surface railway structure, as shown on <a href="#fig_03">Fig. 3</a>, and all temporary
+posts under these I-beams were removed. The bents were
+framed with a jack, as tightly as possible, and very little settlement of
+the track occurred.</p>
+
+<p>A cradle was then built under the 24-in. water main and placed
+on girders "C," and, as a temporary footwalk had been constructed on
+the west side of the avenue, it will be seen that all structures were thus
+carried on girders "C."</p>
+
+<p>All structures were put on the girders "C" before continuing the
+excavation on the sides of the avenue because, in case of a slide of
+rock, there would be less danger than to individual structures. The
+<span class='pagenum'><a name="Page_317" id="Page_317">[317]</a></span>outside piers, on which the girders "C" rested, might even be lost,
+without affecting the stability of the structure, and posting could
+readily be done beneath these girders in case of necessity.</p>
+
+<p>A very careful record of levels, taken on the elevated railway
+columns, was kept, observations being made during each jacking up
+and at least twice a week during the progress of the work. The columns
+were usually kept about &frac12; in. high so as to allow for compression in
+the timber bents.</p>
+
+<p>As a rule, no jacking of the elevated railway structure was done
+while trains were passing over, and trains were flagged during the
+operation. There was generally very little delay, as all jacking was
+done between 10.30 <span class="smcap">a.m.</span> and 2.30 <span class="smcap">p.m.</span>, when the traffic was lightest,
+and frequently the jacking was done between trains, causing no delay
+whatever. Steel clamps were placed, three on the top and three on the
+bottom of each set of the girders "C," to bind them together and cause
+them to act as a unit.</p>
+
+<p>All structures then being supported on girders "C," which were
+carried on four concrete piers resting on the central rock core, the
+excavation on the sides of the avenue was continued down to sub-grade
+and the east and west portions of the concrete north abutment were
+constructed. The central rock core was about 36 ft. wide on the top
+and 45 ft. wide on the bottom, and at the center of 32d Street it was
+about 42 ft. high.</p>
+
+<p>It was the original intention to excavate a sufficient width of the
+sides of the avenue to erect six rows of the permanent steel viaduct,
+5 ft. from center to center, and this was done on the south portion of
+the work. On the north portion, however, the rock was of poor quality,
+and it was thought best to excavate for only five rows at first, to erect
+the five rows of permanent steel and put the timber bents in place
+under the ends of the girders "C," in order to give them some support
+while the outside concrete piers were being removed and the excavation
+was being widened out to permit the erection of the sixth row. Additional
+raker braces were put in these bents temporarily, and were
+removed when the sixth row of steel had been erected. This is shown
+on <a href="#fig_04">Figs. 4</a> and <a href="#fig_05">5</a>.</p>
+
+<div class="figcenter" style="width: 577px;">
+<img id="plate48_fig1" src="images/p48f1.jpg" width="577" height="448"
+alt="Plate XLVIII, Fig. 1.&mdash; TW 33, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st St., showing rock excavation and supports of 9th Ave. structures. Dec. 28, 07."
+title="Plate XLVIII, Fig. 1.&mdash; TW 33, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st St., showing rock excavation and supports of 9th Ave. structures. Dec. 28, 07." />
+<span class="caption">Plate XLVIII, Fig. 1.&mdash; TW 33, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st St., showing rock excavation and supports of 9th Ave. structures. Dec. 28, 07.</span>
+</div>
+
+<div class="figcenter" style="width: 580px;">
+<img id="plate48_fig2" src="images/p48f2.jpg" width="580" height="449"
+alt="Plate XLVIII, Fig. 2.&mdash; TW 39, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st Street, showing rock excavation and permanent steel work. March 24, 08."
+title="Plate XLVIII, Fig. 2.&mdash; TW 39, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st Street, showing rock excavation and permanent steel work. March 24, 08." />
+<span class="caption">Plate XLVIII, Fig. 2.&mdash; TW 39, P.T. &amp; T.R.R. Co. Terminal Station West. East side of 9th Ave. looking North from 31st Street, showing rock excavation and permanent steel work. March 24, 08.</span>
+</div>
+
+<div class="figcenter" style="width: 578px;">
+<img id="plate48_fig3" src="images/p48f3.jpg" width="578" height="448"
+alt="Plate XLVIII, Fig. 3.&mdash; TW 73, P.T. &amp; T.R.R. Co. Terminal Station West. West side of Ninth Ave. Jacking up girders &quot;C&quot; at Elevated Railroad Column 491, showing method of taking weight on permanent viaduct girders. Nov. 14, 08."
+title="Plate XLVIII, Fig. 3.&mdash; TW 73, P.T. &amp; T.R.R. Co. Terminal Station West. West side of Ninth Ave. Jacking up girders &quot;C&quot; at Elevated Railroad Column 491, showing method of taking weight on permanent viaduct girders. Nov. 14, 08." />
+<span class="caption">Plate XLVIII, Fig. 3.&mdash; TW 73, P.T. &amp; T.R.R. Co. Terminal Station West. West side of Ninth Ave. Jacking up girders &quot;C&quot; at Elevated Railroad Column 491, showing method of taking weight on permanent viaduct girders. Nov. 14, 08.</span>
+</div>
+
+<div class="figcenter" style="width: 578px;">
+<img id="plate48_fig4" src="images/p48f4.jpg" width="578" height="450"
+alt="Plate XLVIII, Fig. 4.&mdash; TW 58, P.T. &amp; T.R.R. Co. Terminal Station West. East side of Ninth Ave. looking North from 31st St., showing underpinning of Ninth Ave. Structures. Aug. 10, 08."
+title="Plate XLVIII, Fig. 4.&mdash; TW 58, P.T. &amp; T.R.R. Co. Terminal Station West. East side of Ninth Ave. looking North from 31st St., showing underpinning of Ninth Ave. Structures. Aug. 10, 08." />
+<span class="caption">Plate XLVIII, Fig. 4.&mdash; TW 58, P.T. &amp; T.R.R. Co. Terminal Station West. East side of Ninth Ave. looking North from 31st St., showing underpinning of Ninth Ave. Structures. Aug. 10, 08.</span>
+</div>
+
+<p><a href="#plate47_fig4">Fig. 4, Plate XLVII</a>, and <a href="#plate48_fig1">Fig. 1, Plate XLVIII</a>, show the structures
+supported on the central rock core and the excavation on the
+east side to permit of the erection of the permanent viaduct girders.<span class='pagenum'><a name="Page_318" id="Page_318">[318]</a></span>
+<a href="#plate48_fig1">Fig. 1, Plate XLVIII</a>, shows also the easterly portion of the concrete
+north abutment. <a href="#plate48_fig2">Fig. 2, Plate XLVIII</a>, shows five rows of the permanent
+viaduct girders erected on the east side of the work.</p>
+
+<p>The excavation of the sides of the avenue having been completed,
+and six rows of permanent viaduct girders erected on both sides, timber
+bents, as shown on <a href="#fig_02">Figs. 2</a>, <a href="#fig_04">4</a>, <a href="#fig_05">5</a>, and <a href="#fig_06">6</a>, were erected on this steel to
+support the ends of the girders "C" and carry the structure while the
+rock core was being excavated. <a href="#plate48_fig3">Fig. 3, Plate XLVIII</a>, shows the method
+of taking the weight on these bents. Four 80-ton jacks were used, and
+oak blocks were placed on the top of each jack to transmit pressure
+to a temporary oak cap under the girders "C" independent of the
+bents; all four of these jacks were operated simultaneously, and the
+girders "C" were lifted off the bents and clear of the concrete piers.
+Oak filling pieces were then inserted between the bents and the girders
+"C," so that when the jacks were released the girders "C" were clear
+of the concrete piers. <a href="#plate48_fig3">Fig. 3, Plate XLVIII</a>, shows that the girders
+have been lifted off the piers. Elevations were taken on each set of
+girders during each operation, and careful observations were made on
+the elevated railway columns. Where the rock was very close to these
+bents, the open space between the posts was filled with blocking so that
+there would be less danger of the bent shifting if struck by blasted
+materials. <a href="#plate48_fig3">Fig. 3, Plate XLVIII</a>, shows one of these bents filled with
+blocking.</p>
+
+<p>All structures being carried on girders "C," which, in turn, were
+carried on the sides of the permanent viaduct, the central core was
+excavated. <a href="#plate48_fig4">Fig. 4, Plate XLVIII</a>, and <a href="#plate49_fig1">Figs. 1</a>,
+<a href="#plate49_fig2">2</a>, <a href="#plate49_fig3">3</a>, and <a href="#plate49_fig4">4, Plate
+XLIX</a>, show various views of the work at this stage.</p>
+
+<p>The central portion of the viaduct was then erected, and, using
+concrete piers and timber bents, all structures were placed on its deck.
+<a href="#plate49_fig3">Fig. 3, Plate XLIX</a>, shows the piers under the elevated railway
+columns prior to the removal of girders "C."</p>
+
+<div id="Page_319" class="figcenter" style="width: 514px;">
+<a href ="images/fig06.png">
+<img id="fig_06" src="images/fig06tn.png" width="514" height="358" alt="GENERAL ARRANGEMENT OF TEMPORARY AND PERMANENT STRUCTURES" title="GENERAL ARRANGEMENT OF TEMPORARY AND PERMANENT STRUCTURES" />
+<span class="caption">Fig. 6.</span> (full page image)<br />
+GENERAL ARRANGEMENT OF TEMPORARY AND PERMANENT STRUCTURES
+</a>
+</div>
+
+<p>During the latter part of 1908 a 48-in. cast-iron water main was
+laid by the city on a cradle built by the Railroad Company on girders
+"C" on the east side of the avenue. This is part of the high-pressure
+system, and the location and elevation of this water main were taken
+into consideration when the underpinning was designed. This main,
+and the 48-in. cast-iron sewer bracketed to girders "C," are shown on
+<a href="#plate48_fig4">Fig. 4, Plate XLVIII</a>.</p>
+
+<p><span class='pagenum'><a name="Page_320" id="Page_320">[320]</a></span></p><p>Elevations had been taken on marks on the elevated railway
+columns between 30th and 34th Streets at the time the original surveys
+were made, in 1902, and these marks were used to test the level of the
+structure during the progress of the excavation.</p>
+
+<p>At the extreme south end of the work the procedure was changed.
+The east side was excavated down to sub-grade, the east portion of the
+south abutment was constructed, and six rows of the permanent steel
+viaduct were erected. Very little excavation had been done on the west
+side of the avenue at the south end of the work, and it would have
+delayed the completion of the work to have waited for the excavation
+for and the construction of the west portion of the south abutment
+and the erection of the steel; therefore, instead of supporting the
+girders "C" on the central rock core, the east ends were taken up on
+the permanent viaduct girders, and the west ends were supported on a
+concrete pier on the rock. The central portion of the avenue was
+excavated in advance of the west portion. The permanent viaduct
+girders were put in place from east to west across the avenue, and the
+girders "C" were supported on the deck of the permanent viaduct
+approximately under the west elevated railway columns before the west
+portion of the avenue was excavated, the central portion of the south
+abutment having been constructed before the west portion. This procedure
+was adopted only at the north girders "C" at elevated railway
+column No. 488, the south set of girders "C" being on the rock immediately
+south of the south abutment. <a href="#plate49_fig2">Figs. 2</a> and <a href="#plate49_fig4">4, Plate XLIX</a>,
+and <a href="#plate52_fig2">Fig. 2, Plate LII</a>, show various stages of the work at the
+south end.</p>
+
+<div class="figcenter" style="width: 576px;">
+<img id="plate49_fig1" src="images/p49f1.jpg" width="576" height="451"
+alt="Plate XLIX, Fig. 1.&mdash; TW 60, P.T. &amp; T.R.R. Co. Terminal Station West. Under Ninth Ave., looking South from North abutment, showing underpinning and excavation of rock core. Aug. 13, 08."
+title="Plate XLIX, Fig. 1.&mdash; TW 60, P.T. &amp; T.R.R. Co. Terminal Station West. Under Ninth Ave., looking South from North abutment, showing underpinning and excavation of rock core. Aug. 13, 08." />
+<span class="caption">Plate XLIX, Fig. 1.&mdash; TW 60, P.T. &amp; T.R.R. Co. Terminal Station West. Under Ninth Ave., looking South from North abutment, showing underpinning and excavation of rock core. Aug. 13, 08.</span>
+</div>
+
+<div class="figcenter" style="width: 577px;">
+<img id="plate49_fig2" src="images/p49f2.jpg" width="577" height="449"
+alt="Plate XLIX, Fig. 2.&mdash; TW 84, P.T. &amp; T.R.R. Co. Terminal Station West. View looking toward Ninth Ave. from South side of 31st St., 200 feet West of Ninth Ave. Jan. 28, 09."
+title="Plate XLIX, Fig. 2.&mdash; TW 84, P.T. &amp; T.R.R. Co. Terminal Station West. View looking toward Ninth Ave. from South side of 31st St., 200 feet West of Ninth Ave. Jan. 28, 09." />
+<span class="caption">Plate XLIX, Fig. 2.&mdash; TW 84, P.T. &amp; T.R.R. Co. Terminal Station West. View looking toward Ninth Ave. from South side of 31st St., 200 feet West of Ninth Ave. Jan. 28, 09.</span>
+</div>
+
+<div class="figcenter" style="width: 589px;">
+<img id="plate49_fig3" src="images/p49f3.jpg" width="589" height="460"
+alt="Plate XLIX, Fig. 3.&mdash; TW 88, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. Center line of 32nd St., looking East from Sta. 183+50, showing excavation under Ninth Avenue, permanent concrete piers under Elevated Railway Columns and removal of temporary shoring girders &quot;C&quot;. April 8, 09."
+title="Plate XLIX, Fig. 3.&mdash; TW 88, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. Center line of 32nd St., looking East from Sta. 183+50, showing excavation under Ninth Avenue, permanent concrete piers under Elevated Railway Columns and removal of temporary shoring girders &quot;C&quot;. April 8, 09." />
+<span class="caption">Plate XLIX, Fig. 3.&mdash; TW 88, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. Center line of 32nd St., looking East from Sta. 183+50, showing excavation under Ninth Avenue, permanent concrete piers under Elevated Railway Columns and removal of temporary shoring girders &quot;C&quot;. April 8, 09.</span>
+</div>
+
+<div class="figcenter" style="width: 594px;">
+<img id="plate49_fig4" src="images/p49f4.jpg" width="594" height="457"
+alt="Plate XLIX, Fig. 4.&mdash; TW 95, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View under Ninth Avenue looking Southward from 100 feet South of center line, showing underpinning of Ninth Avenue structure taken at sub-grade. May 25, 09."
+title="Plate XLIX, Fig. 4.&mdash; TW 95, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View under Ninth Avenue looking Southward from 100 feet South of center line, showing underpinning of Ninth Avenue structure taken at sub-grade. May 25, 09." />
+<span class="caption">Plate XLIX, Fig. 4.&mdash; TW 95, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View under Ninth Avenue looking Southward from 100 feet South of center line, showing underpinning of Ninth Avenue structure taken at sub-grade. May 25, 09.</span>
+</div>
+
+<p>It was made a practice all through the work to transfer the weight
+of the structures very positively from one support to another by lifting
+them bodily by jacks, and putting in filler pieces before releasing the
+jacks, not trusting to wedging to transfer the loads. In fact, apart
+from the boxing-in of the surface railway concrete, no wedges whatever
+were used. This appears to have been a decided advantage, for,
+with the constant pounding of trains on the elevated railway and the
+jarring due to heavy trucks on the pavement blocks, it is very likely
+that wedging would have become loosened and displaced, whereas, with
+blocking, there was little or no tendency toward displacement due to
+vibration. Although the vibration of the structure, when a long
+length was supported on girders "C" resting on the permanent viaduct
+<span class='pagenum'><a name="Page_321" id="Page_321">[321]</a></span>girders on the sides of the avenue, appeared to be considerable, not
+only vertically but transversely, very careful observation showed that
+the sag in the girder "C" due a live load of three elevated railway
+trains, one surface railway car, and one heavy truck, amounted to 1/8; in.
+The sideway vibration did not amount to more than 1/32 in. on either side
+of the normal position. More vibration was caused by heavy trucks
+and wagons going over the stone pavement than by the elevated railway
+trains or surface cars.</p>
+
+<p>No blasting was done near the supports of the elevated railway
+structure while trains were passing over it, and occasionally trains
+were stopped during a heavy or uncertain blast. A watchman on the
+surface, day and night, and at first one and later two flagmen on the
+elevated railway structure, were on duty at all times, reporting to the
+Interborough Rapid Transit Company, by whom they were employed.
+Log mats and timber protection for the girders and the columns of
+the permanent viaduct were used, as shown by <a href="#plate49_fig1">Figs. 1</a> and <a href="#plate49_fig4">4, Plate
+XLIX</a>, during the excavation of the rock core, and timber was also
+used to protect the face of the completed portions of the concrete
+abutments.</p>
+
+<p>In excavating the sides of the avenue, the rock broke better on
+the east than on the west side, where large seams developed and some
+slides occurred.</p>
+
+<p><i>Abutments.</i>&mdash;As shown on <a href="#fig_07">Fig. 7</a>, the face of the north abutment
+has a batter of 2 in. to the foot, and the face of the south abutment
+has a variable batter, the base being on a grade and the bridge seat
+being level, and both maintaining a uniform distance from the center
+of the Terminal Yard. The back walls of the abutments were not
+built until the steel had been put in place.</p>
+
+<p>No attempt was made to water-proof these abutments, but, in the
+rear of the wall, open spaces were left, about 6 ft. from center to
+center, which were connected with drain pipes at the base of and
+extending through the wall, for the purpose of carrying off any water
+that might develop in the rock. These drains were formed by building
+wooden boxes with the side toward the rock open and the joints
+in the boxes and against the rock plastered with mortar in advance
+of the wall. A hose was used to run water through these drains during
+the placing of the concrete, for the purpose of washing out any grout
+which might run into them. Each box was washed out at frequent
+<span class='pagenum'><a name="Page_322" id="Page_322">[322]</a></span>intervals, and there was no clogging of the drains whatever. This
+method of keeping the drains open was adopted and used successfully
+for the entire work. The abutments were built of concrete, and the
+mixture was 1 part of cement, 3 parts of sand, and 6 parts of broken
+stone.</p>
+
+<p>The concrete was mixed in a No. 3 Ransome mixer, and was placed
+very wet. No facing mixture or facing diaphragms were used, but
+the stone was spaded away from the face of the wall as the concrete
+was laid. Chutes were used inside the form, if the concrete had to
+drop some distance. Work was continued day and night, without any
+intermission, from the time of commencement to the time of completion
+of each section.</p>
+
+<p>The face of the concrete wall was rubbed and finished in a manner
+similar to that used on the walls between Ninth and Tenth Avenues,
+as described later.</p>
+
+<p><a href="#plate52_fig2">Fig. 2, Plate LII</a>, shows the east and central portions of the south
+abutment, completed and carrying the permanent viaduct, and the
+excavation completed for the west portion.</p>
+
+
+<p class="sectionh">Work Between Ninth and Tenth Avenues.</p>
+
+<p><i>General Description.</i>&mdash;The work involved the excavation of about
+5.4 acres, between the west house line of Ninth Avenue and the east
+house line of Tenth Avenue, to an average depth of about 50 ft., the
+construction of a stone masonry portal at Tenth Avenue leading to the
+River Tunnels, and the construction around the site of the concrete
+retaining and face walls.</p>
+
+<p>The following estimated quantities appear in the contract: Excavation
+of rock in trenches, 3,400 cu. yd.; excavation of rock in pit,
+377,000 cu. yd.; excavation of all materials except rock in trenches,
+6,500 cu. yd.; excavation of all materials except rock in pit, 34,000
+cu. yd.; concrete, 1:3:6, in retaining walls, 4,580 cu. yd.; concrete,
+1:3:6, in face walls, 7,460 cu. yd.; concrete, 1:2:3, with &frac34;-in. stone,
+in face walls, 4,100 cu. yd.; stone masonry in portal, 247 cu. yd.,
+etc., etc.</p>
+
+<div id="Page_323" class="figcenter" style="width: 598px;">
+<a href ="images/fig07.png">
+<img id="fig_07" src="images/fig07tn.png" width="598" height="381" alt="NINTH AVE. ABUTMENTS &amp; KEY PLAN" title="NINTH AVE. ABUTMENTS &amp; KEY PLAN" />
+<span class="caption">Fig. 7.</span> (full page image)<br />
+NINTH AVE. ABUTMENTS &amp; KEY PLAN
+</a>
+</div>
+
+<p>As previously stated, the contract price included the placing of
+all excavated material on scows at Pier 62, North River. Prior to this
+contract this pier had been used by the New York Contracting Company-Pennsylvania
+Terminal, for the disposal of excavated material
+<span class='pagenum'><a name="Page_324" id="Page_324">[324]</a></span>from east of Ninth Avenue. In order to get the material to the pier,
+the contractor had excavated a cut under Ninth Avenue which came
+to the grade of 32d Street about midway between Ninth and Tenth
+Avenues, and a trestle was constructed from this point over Tenth
+Avenue and thence to the pier. <a href="#plate47_fig2">Fig. 2, Plate XLVII</a>, shows the east
+end of this cut, and <a href="#plate50_fig1">Fig. 1, Plate L</a>, shows the trestle, looking east from
+Tenth Avenue.</p>
+
+<p>A 30-ton steam shovel was brought to the south side of the work,
+and commenced operating on July 9th, 1906. After working there
+about a month, the earth had been practically stripped off the rock,
+and the shovel was moved over to the north side where it excavated
+both earth and rock until August 10th, 1907.</p>
+
+<p>At three points south of 32d Street and at one point north of 32d
+Street near Tenth Avenue, cuts were made in the rock to sub-grade,
+and from these cuts, together with the cuts on the west side of Ninth
+Avenue, all widening out was done and the excavation was completed.
+<a href="#plate50_fig1">Fig. 1, Plate L</a>, shows the excavation of the three cuts on the south
+side of 32d Street, the steam shovel operating on the north side of that
+street, and the material-disposal tracks and trestle. <a href="#plate52_fig3">Fig. 3, Plate LII</a>,
+shows the cuts joined up and the excavation along the south side
+practically completed.</p>
+
+<p>On the north side of the work, between Stations 182 + 90 and
+183 + 65, the rock was low, and provision had to be made for maintaining
+the yards to the north of the site. Therefore a rubble-masonry
+retaining wall was built, with the face about 2 ft. north of the face
+of the proposed concrete wall which was to be put in later. On the
+same side of the work, between Stations 188 + 24 and 188 + 46, the
+rock was exceedingly poor, and as a small frame house on the adjoining
+lot was considered to be in an unsafe condition, a rubble masonry
+retaining wall was built. As the building adjoining the south side of
+the work at Tenth Avenue was on an earth foundation, it was necessary
+to underpin it before the excavation could be done. The building
+was supported on needles, and rubble masonry was put in from the
+bottom of the old foundation to the rock. The foundation of 413
+West 31st Street, immediately west of the Express Building site, was
+of very poor masonry, and it was necessary to rebuild it prior to taking
+out the adjoining excavation.</p>
+
+<div class="figcenter" style="width: 578px;">
+<img id="plate50_fig1" src="images/p50f1.jpg" width="578" height="450"
+alt="Plate L, Fig. 1.&mdash; TW 23, P.N.Y. &amp; L.I.R.R. Terminal Station West. View looking Eastward from Tenth Ave., showing work between Ninth &amp; Tenth Avenues. Dec. 26, 06."
+title="Plate L, Fig. 1.&mdash; TW 23, P.N.Y. &amp; L.I.R.R. Terminal Station West. View looking Eastward from Tenth Ave., showing work between Ninth &amp; Tenth Avenues. Dec. 26, 06." />
+<span class="caption">Plate L, Fig. 1.&mdash; TW 23, P.N.Y. &amp; L.I.R.R. Terminal Station West. View looking Eastward from Tenth Ave., showing work between Ninth &amp; Tenth Avenues. Dec. 26, 06.</span>
+</div>
+
+<div class="figcenter" style="width: 581px;">
+<img id="plate50_fig2" src="images/p50f2.jpg" width="581" height="452"
+alt="Plate L, Fig. 2.&mdash; TW 35, P.T. &amp; T.R.R. Co. Terminal Station West. View looking Northwest from Sta. 184, 120 feet South of center line. Dec. 31, 07."
+title="Plate L, Fig. 2.&mdash; TW 35, P.T. &amp; T.R.R. Co. Terminal Station West. View looking Northwest from Sta. 184, 120 feet South of center line. Dec. 31, 07." />
+<span class="caption">Plate L, Fig. 2.&mdash; TW 35, P.T. &amp; T.R.R. Co. Terminal Station West. View looking Northwest from Sta. 184, 120 feet South of center line. Dec. 31, 07.</span>
+</div>
+
+<div class="figcenter" style="width: 580px;">
+<img id="plate50_fig3" src="images/p50f3.jpg" width="580" height="451"
+alt="Plate L, Fig. 3.&mdash; TW 96, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View looking West from Ninth Avenue Elevated Railway, showing condition of work. May 26, 09."
+title="Plate L, Fig. 3.&mdash; TW 96, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View looking West from Ninth Avenue Elevated Railway, showing condition of work. May 26, 09." />
+<span class="caption">Plate L, Fig. 3.&mdash; TW 96, P.T. &amp; T.R.R. Co. N.R. Div. Terminal Station West. View looking West from Ninth Avenue Elevated Railway, showing condition of work. May 26, 09.</span>
+</div>
+
+<div class="figcenter" style="width: 576px;">
+<img id="plate50_fig4" src="images/p50f4.jpg" width="576" height="447" alt="Plate L, Fig. 4.&mdash; TW 104, P.N.Y. &amp; L.I.R.R. Terminal Station West. View from Tenth Avenue looking East, showing progress of concrete walls. Aug. 7, 09." title="Plate L, Fig. 4.&mdash; TW 104, P.N.Y. &amp; L.I.R.R. Terminal Station West. View from Tenth Avenue looking East, showing progress of concrete walls. Aug. 7, 09." />
+<span class="caption">Plate L, Fig. 4.&mdash; TW 104, P.N.Y. &amp; L.I.R.R. Terminal Station West. View from Tenth Avenue looking East, showing progress of concrete walls. Aug. 7, 09.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_325" id="Page_325">[325]</a></span></p><p>Along the north side, between Stations 186 + 50 and 187 + 50,
+the walls supporting the adjoining back yards were of poor quality
+and had to be renewed by the contractor before excavation could be
+done.</p>
+
+<p>The excavated material was loaded by derricks on cars at the top
+of the excavation, these cars being on tracks having a direct connection
+with the disposal trestle, as shown by <a href="#plate50_fig1">Fig. 1, Plate L</a>. As soon
+as it could be done, derricks were placed at the bottom of the excavation;
+tracks were then laid out there, and the excavated material was
+loaded on cars at the bottom and hoisted by derricks to cars on the
+disposal trestle. A locomotive was lowered to the bottom of the excavation
+on August 25th, 1907, and a derrick started operating at the
+bottom on August 27th, 1907. The commencement of this work by
+derricks at the bottom is shown by <a href="#plate52_fig3">Fig. 3, Plate LII</a>. In general,
+the disposal tracks were maintained about on the center line of 31st
+Street until the excavation had been carried as close to them as possible,
+and on October 16th, 1907, they were shifted to the extreme
+north side of the work, as shown by <a href="#plate50_fig2">Fig. 2, Plate L</a>. A portion of
+the old trestle was left in place near Tenth Avenue, a derrick was
+erected thereon, and the tracks were used for cars to receive the
+excavated material hoisted from sub-grade. The disposal trestle was
+maintained in this position until such time as it would interfere with
+the excavation, and then the tracks were abandoned. This was done
+on November 11th, 1908. <a href="#plate50_fig3">Fig. 3, Plate L</a>, shows the finishing of
+the excavation on the north side of the work. On August 30th, 1908,
+a cut was made under Ninth Avenue at sub-grade, and cars could then
+be run from Seventh to Tenth Avenue at sub-grade. On October 24th,
+1908, the connection with the disposal trestle east of Ninth Avenue
+was abandoned, and all excavated material was hoisted from sub-grade
+at Tenth Avenue by derricks.</p>
+
+<p>As previously stated, the contractor was required to make complete
+disposal of all excavated material after January 1st, 1909, but
+was allowed the use of the pier until January 20th, 1909, after which
+date the materials were hoisted by derricks at Tenth Avenue, loaded
+on 2-horse trucks, and transported to the 30th Street pier, North River,
+where it was loaded on scows by two electric derricks. A considerable
+amount of the rock excavation was broken up and used for back-fill.</p>
+
+<p><span class='pagenum'><a name="Page_326" id="Page_326">[326]</a></span></p><p><i>Earth Excavation.</i>&mdash;Practically all the earth excavation, amounting
+to about 57,000 cu, yd., was done with steam shovels. The average
+quantity of earth excavated by a steam shovel per 10-hour shift was
+180 cu. yd. This material was loaded on side-dump cars and taken to
+the disposal pier where it was dumped through chutes to the decks of
+scows. Inasmuch as the quantity of earth excavation was small, as
+compared with the rock, the earth was used principally for the first
+layer on the scows for padding, so that small stones might be dumped
+through the chutes without injuring the decks.</p>
+
+<p><i>Rock Excavation.</i>&mdash;As previously stated, the rock broke better on
+the south than on the north side, where there were several slides, and
+considerable excavation had to be taken out beyond the neat line required
+in the specifications. The worst slide occurred at midnight on
+July 3d, 1909, at about Station 188 + 50. The last blast, to complete
+the excavation to sub-grade at this point, had been fired in the afternoon
+of the same day, and the mucking was practically completed.
+Great care had been taken in excavating near this point, as it was
+evident that the rock was not of a very stable character, but, when the
+excavation had been completed, it was thought that the rock remaining
+in place would stand. The volume of material brought down by this
+slide amounted to about 200 cu. yd. The rock on the south side broke
+very well, and there were no slides of any consequence.</p>
+
+<p>The drill holes were laid out by the blaster, and the general method
+of drilling for different classes of work was as follows: In breaking
+down, the holes were started about 8 ft. apart, on a slight batter, so
+that at the bottom they would be considerably less than 8 ft. apart.
+They were drilled about 10 ft. deep, and blasting logs were used, as it
+was necessary to load quite heavily in order to lift the material and
+start the cut. After the cut had been made, side holes were shot to
+widen out sufficiently to start another cut.</p>
+
+<p>After a side cut about 20 ft. deep had been made, the side holes
+were drilled 20 ft. deep, and the holes were loaded and tamped for the
+full 20-ft. cut. Under the terms of the specifications, the contractor
+was required to complete the excavation on the sides by drilling broaching
+holes.</p>
+
+<p>The maximum length of drill steel was about 20 ft., and, where the
+excavation plane of broaching was more than 20 ft. in depth, the contractor
+was permitted to start the holes back of the broaching line, in
+<span class='pagenum'><a name="Page_327" id="Page_327">[327]</a></span>order to allow for setting up the drills on the second lift. A distance
+of about 8 in. was usually allowed for setting up a drill. The broaching
+line was painted on the surface of the rock in advance of the
+drilling, and the batter of the drill was tested with a specially designed
+hand-level in which the bubble came to a central position when the face
+of the level was on the required batter. Holes were also drilled in
+front of this broaching line, and, when the excavation had been taken
+out to within about 6 ft. in front of it, the holes immediately in front
+were loaded, and also about every third one of the broaching holes,
+and, unless the rock was very bad, it usually broke sharply at the
+broaching line. Occasionally, the broaching holes which were not
+loaded were filled with sand, which gave rather better results than
+leaving them open.</p>
+
+<p>In the steam-shovel work on the east side of Ninth Avenue, spring
+holes were used. They were formed by drilling a 20-ft. hole and exploding
+at the bottom of it, without tamping, two or three sticks of dynamite,
+and repeating this process with heavier charges until there had been
+formed at the bottom of the hole a large cavity which would hold from
+100 to 200 lb. of dynamite. Face holes and breast holes were also
+drilled, and it was possible by this method to drill and break up a cut
+20 ft. deep and 15 ft. thick. The only place where spring holes were
+used on this work was on the east side of Ninth Avenue where the
+heavy cutting was sometimes extended beyond the east house line.</p>
+
+<p>From the best records obtainable, the average progress in drilling
+was about 33 lin. ft. per 8-hour shift. The average number of cubic
+yards of excavation per drill shift was 13.9, and the average amount
+of drilling per cubic yard of excavation was 2.4 ft.; this covered more
+than 27,000 drill shifts.</p>
+
+<p>The dynamite was practically all 60%, and the average excavation
+per pound of dynamite was 2.2 cu. yd. The contractor employed an
+inspector of batteries and fuses, who, using an instrument for that
+purpose, tested the wiring of each blast prior to firing, in order to discover
+any short circuits, and thus prevent the danger of leaving unexploded
+dynamite in the holes.</p>
+
+<p>The average quantity of excavation per derrick shift of 10 hours,
+covering 7,400 shifts, 87% of the excavation being rock, was 50 cu. yd.,
+and the average force per shift, including only foreman and laborers,
+was 13 men. It was found that a derrick operating at the top of a<span class='pagenum'><a name="Page_328" id="Page_328">[328]</a></span>
+20-ft. cut would handle about 40 cu. yd. per shift, whereas, if operating
+at the bottom of the cut, it would handle about 60 cu. yd. per shift.
+The elevator derricks at Tenth Avenue were very efficient, and each
+could take care of the material from four derricks at the bottom, hoisting
+250 cu. yd. per shift a height of 60 ft.</p>
+
+<p><i>Concrete Retaining and Face Walls.</i>&mdash;It was essential to have the
+greatest space possible at the bottom of the excavation, and, inasmuch
+as the yard was to be left open, it was necessary to provide some facing
+for the rock on the sides in order to prevent disintegration, due to
+exposure, and give a finished appearance to the work. Above the rock
+surface a retaining wall of gravity section was designed, the top being
+slightly higher than the yards of the adjoining properties. The face
+wall was designed to be as thin as possible, in order to allow the
+maximum space for tracks.</p>
+
+<p>The excavation, therefore, was laid out so that the back of the
+retaining wall would not encroach on the adjoining property, but would
+practically coincide with the property line at positions of maximum
+depth.</p>
+
+<p>The batter on the face of the wall was 2 in. per ft., and a bridge
+seat 3&frac12; ft. wide was formed at an elevation of 22 ft., minimum clearance,
+above the top of the rail. This bridge seat was made level. The
+maximum height of the south wall is 49 ft., and of the north wall
+65 ft.</p>
+
+<p>The face walls were classed as "Upper Face Walls," extending from
+the base of the retaining wall to the bridge seat, and as "Lower Face
+Walls," extending from the bridge seat to the base of the wall. The
+general design is shown on <a href="#fig_08">Fig. 8</a>.</p>
+
+<p>In considering the design of the face wall it was felt that, the wall
+being so thin, ample provision should be made to prevent any accumulation
+of water and consequent pressure back of the wall; therefore,
+no attempt was made to water-proof it, but provision was made to carry
+off any water which might appear in the rock. Box drains, 2 ft. wide
+and 6 ft. from center to center, were placed against the rock, so that,
+there being but 4 ft. between the drains, and the wall having a minimum
+thickness of 2 ft., any water in the rock would not have to go
+more than 2 ft. to reach a drain, and would probably pass along the
+face of the rock to a drain rather than through 2 ft. of concrete. These
+drains were connected with pipes leading through the wall at its base.</p>
+
+<p><span class='pagenum'><a name="Page_329" id="Page_329">[329]</a></span></p>
+
+<div class="figcenter" style="width: 554px;">
+<a href ="images/fig08.png">
+<img id="fig_08" src="images/fig08tn.png" width="554" height="385" alt="RETAINING AND FACE WALLS NORTH SIDE" title="RETAINING AND FACE WALLS NORTH SIDE" />
+<span class="caption">Fig. 8.</span> (full page image)<br />
+RETAINING AND FACE WALLS NORTH SIDE
+</a>
+</div>
+
+<p><span class='pagenum'><a name="Page_330" id="Page_330">[330]</a></span></p><p>These box drains occurred so frequently, and decreased the section
+of the wall so materially, that it was thought desirable to tie the
+wall to the rock. This was done by drilling into the rock holes from
+6 to 15 ft. in depth, and grouting into each hole a 1&frac12;-in. rod having a
+split end and a steel wedge. The outer end of each rod was fitted with
+a 12 by 12 by &frac12;-in. plate and a nut, and extended into the wall, thus
+tying the concrete securely to the rock. The drains being 6 ft. from
+center to center, the tie-rods were placed midway between them, and
+6 ft., from center to center, vertically and horizontally. <a href="#fig_08">Fig. 8</a> shows
+the arrangement of these rods and drains. Around the Express Building
+site, just west of Ninth Avenue, on the south side of the work, the
+bridge seat was omitted, and the face wall was designed 2 ft. thick
+from top to bottom. The batter on the 31st Street wall was made
+variable, the top and bottom being constant distances from the center
+line and on different grades.</p>
+
+<p>The retaining walls were water-proofed with three layers of felt
+and coal-tar pitch, which was protected by 4 in. of brick masonry. A
+6-in. vitrified drain pipe was laid along the back of the wall, with the
+joints open on the lower half, and this was covered with 1 ft. of broken
+stone and sand before any back-fill was placed on it.</p>
+
+<p>The arrangement of the drains was as follows: The 6-in. drain
+back of the retaining wall was connected with one of the box drains in
+the rear of the face wall by a cast-iron pipe or wooden box every
+24 ft., and this ran through the base of the retaining wall. Midway
+between these pipes, a connection was made at the bridge seat between
+the drain in the rear of the face wall and the gutter formed at the rear
+of the bridge seat to carry off rain-water coming down the face of the
+wall above. All the box drains, except those connected with the drains
+back of the retaining wall, were sealed at the elevation of the base of
+the retaining wall, as noted previously.</p>
+
+<p>The specifications required vitrified pipe to be laid through the
+retaining wall, but, owing to the difficulty of holding the short lengths
+of pipe in place during the laying of wet concrete, they were dispensed
+with, and either iron pipes or wooden boxes were used.</p>
+
+<p><i>Tie-Rods.</i>&mdash;When the excavation on the sides had been completed,
+movable drilling platforms were erected, as shown by <a href="#plate50_fig4">Fig. 4, Plate
+L</a>. The holes were drilled on a pitch of 2 in. per ft. with the
+horizontal. The depths of the holes were decided by the engineer, and
+<span class='pagenum'><a name="Page_331" id="Page_331">[331]</a></span>were on the basis of a minimum depth of 5 ft. in perfect rock; the
+character of the rock, therefore, and the presence of seams, determined
+the depths of the holes. Each hole was partly filled with grout, and
+the rod, with the steel wedge in the split end, was inserted and driven
+with a sledge so that the wedge, striking the bottom of the hole first,
+would cause the split end of the rod to open. Each hole was then
+entirely filled with neat cement grout.</p>
+
+<p><i>Box Drains.</i>&mdash;Various methods of forming the box drains were considered,
+such as using half-tile drains, or a metal form, or a collapsible
+form which could be withdrawn, but it was finally decided to build boxes
+in which the side toward the rock was open and the joints in the boxes
+and against the rock were plastered with cement mortar. These boxes
+were left in place. <a href="#plate51_fig1">Fig. 1, Plate LI</a>, shows the tie-rods and box drains
+in place, and holes being cut near the bottom of the drains for the
+pipes leading through the wall.</p>
+
+<p><i>Forms.</i>&mdash;<a href="#plate51_fig1">Fig. 1, Plate LI</a>, shows the form used on the south
+side of the work. The materials were of good quality, and the form,
+which was about 50 ft. long, was used to build twelve sections, or about
+600 ft. of wall. The form was tied in at the top and bottom by cables
+attached to rods drilled into the rock, and it was thought that, with the
+trusses to stiffen the middle section of the form, it would not be necessary
+to use raker braces against it. This would have been desirable, as
+the placing of the raker braces took considerable time. It was found,
+however, that the form was not sufficiently rigid, as it bulged at the
+middle section and could not be held by the trusses. Two or three sets
+of raker braces, about 12 ft. apart, were used, and in addition, rods
+with turnbuckles were placed through the form and fastened to the
+tie-rods, and thus the form was held in place successfully. On the
+forms built later, the trusses were omitted, and raker braces, about
+every 6 ft., were used. The rods which screwed into the turnbuckles
+were removed before the form was moved. The photograph, <a href="#plate52_fig4">Fig. 4,
+Plate LII</a>, was taken inside the concrete form for the lower face
+wall on the north side, and shows the drains leading through the wall,
+the turnbuckles attached to the tie-rods, the cables attached to rods in
+the rock, and the braces to keep the form from coming in; these braces,
+of course, were removed as the concrete came up. The form was built
+low and wedged up into position. After a section of concrete had set
+sufficiently, the wedges were knocked out, the form was lowered and
+<span class='pagenum'><a name="Page_332" id="Page_332">[332]</a></span>moved from the wall, and was then moved along the lowest waling
+piece by block and tackle to its new position.</p>
+
+<p><a href="#plate50_fig4">Fig. 4, Plate L</a>, shows the forms used on the north side of the
+work.</p>
+
+<p>A section, 1 ft. square, at the top of the bridge seat of the lower
+face wall, was left out, so that the bottom of the form for the upper
+face wall could be braced against it. The top of this form was tied
+by cables attached to rods in the rock and by rods with turnbuckles
+running from back to front of the form; braces were also put in from
+the back of the retaining wall form to the walls of buildings along the
+property lines, when this could be done. The middle section of the
+form was held by rods with turnbuckles which passed through the form
+and were fastened to each of the tie-rods drilled into the rock, as was
+also done in the case of the lower face wall. It was generally possible
+to hold the form to true position in this manner, but occasionally it
+had a tendency to bulge; when this occurred, the rods leading through
+the form and fastened to the tie-rods were tightened up, the placing
+of the concrete was slowed up, and no serious bulging occurred.</p>
+
+<p>Bulkheads at the ends of the sections were built of rough planking
+securely braced to the rock, except that a planed board was laid up
+against the face of the form to make a straight joint. At the end of
+each section a V was formed, as shown by <a href="#plate51_fig1">Fig. 1, Plate LI</a>. At all
+corners, a "return," or portion of the wall running at right angles, was
+built, and no section of wall was stopped at a corner.</p>
+
+<p><i>Filling Forms of Lower Face Walls.</i>&mdash;A temporary trestle was
+erected above the elevation of the bridge seat, and a track, leading
+from the mixer to the form to be filled, was laid on it. At the commencement
+of each section a layer of mortar (1 part of cement to 2&frac12;
+parts of sand) was deposited on the bottom. A 1:3:6 mixture of concrete
+was used; it was run from the mixer into dump-cars and deposited
+in the form through chutes, three of which were provided for each
+50-ft. section, the average length. The concrete was mixed wet, and
+was not rammed; the stone was spaded back from the face, and no
+facing mixture or facing diaphragms were used. Work on each section
+was continued day and night without any intermission from the
+time of commencement to the time of completion. At frequent intervals
+the box drains were washed out thoroughly with a hose, in order
+to prevent them from clogging up with grout.</p>
+
+<div class="figcenter" style="width: 575px;">
+<img id="plate51_fig1" src="images/p51f1.jpg" width="575" height="449" alt="Plate LI, Fig. 1.&mdash; TW 66, P.N.Y. &amp; L.I.R.R. Terminal Station West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17, 08." title="Plate LI, Fig. 1.&mdash; TW 66, P.N.Y. &amp; L.I.R.R. Terminal Station West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17, 08." />
+<span class="caption">Plate LI, Fig. 1.&mdash; TW 66, P.N.Y. &amp; L.I.R.R. Terminal Station West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17, 08.</span>
+</div>
+
+<div class="figcenter" style="width: 575px;">
+<img id="plate51_fig2" src="images/p51f2.jpg" width="575" height="451" alt="Plate LI, Fig. 2." title="Plate LI, Fig. 2." />
+<span class="caption">Plate LI, Fig. 2.</span>
+</div>
+
+<div class="figcenter" style="width: 576px;">
+<img id="plate51_fig3" src="images/p51f3.jpg" width="576" height="451"
+alt="Plate LI, Fig. 3.&mdash; P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy. West. Disposal trestle just before demolition. View of South side showing chutes. Jan. 21, 09."
+title="Plate LI, Fig. 3.&mdash; P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy. West. Disposal trestle just before demolition. View of South side showing chutes. Jan. 21, 09." />
+<span class="caption">Plate LI, Fig. 3.&mdash; P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy. West. Disposal trestle just before demolition. View of South side showing chutes. Jan. 21, 09.</span>
+</div>
+
+<div class="figcenter" style="width: 580px;">
+<img id="plate51_fig4" src="images/p51f4.jpg" width="580" height="451"
+alt="Plate LI, Fig. 4.&mdash; A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy. West &amp; Oj. View across North River on line of Tunnels, looking from New York to New Jersey. Feb. 9, 07."
+title="Plate LI, Fig. 4.&mdash; A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy. West &amp; Oj. View across North River on line of Tunnels, looking from New York to New Jersey. Feb. 9, 07." />
+<span class="caption">Plate LI, Fig. 4.&mdash; A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy. West &amp; Oj. View across North River on line of Tunnels, looking from New York to New Jersey. Feb. 9, 07.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_333" id="Page_333">[333]</a></span></p><p>In the first few sections of wall, the form was filled to within 1 in.
+of the top of the bridge seat and allowed to set for about 2 hours; it was
+then finished to the proper elevation with a plaster of 1 part of cement
+to 1 part of sand. This did not prove satisfactory, as there were indications
+of checking and cracking, and, later, the form was filled to the
+required elevation and the surface floated. The form was allowed to
+remain in place for from 18 to 24 hours, depending on the weather.
+In most cases, immediately after the form had been moved, a scaffold
+was erected against the face of the wall, and the face was wet and
+thoroughly rubbed, first with a wooden float and then with a cement
+brick, until the surface was smooth and uniform.</p>
+
+<p>The section 1 ft. square at the top of the bridge seat, which was
+left out in order to brace the bottom of the form for the upper face
+wall, was filled in after the walls had been completed. The old concrete
+was very thoroughly cleaned before the new concrete was placed
+on it, and a gutter was formed at the rear connecting with the box
+drains back of the wall to carry off rain-water coming down the face
+of the upper walls.</p>
+
+<p>In hot weather the walls were thoroughly wetted down several
+times a day for several days after the form had been removed.</p>
+
+<p><i>Upper Face and Retaining Wall.</i>&mdash;In cases where the top of the
+retaining wall was at a higher elevation than the mixer, it was necessary
+to raise the concrete in a bucket with a derrick, and dump it into
+cars on the trestle above the top of the coping. Concrete was deposited
+through chutes, as in the lower face wall, continuously from the bottom
+of the face wall to the top of the retaining wall. At the commencement
+of each section of the retaining wall a layer of mortar was put
+on the rock. A 1:2:3 mixture of concrete was used in the face wall,
+and a 1:3:6 mixture in the retaining wall.</p>
+
+<p>As the face walls were so thin, the number of batches of concrete
+per hour was reduced, for the form filled so rapidly that the concrete,
+before it set, exerted an excessive pressure against the form, and this
+tended to make it bulge. The proper rate at which to place the concrete
+behind a form 50 ft. long, with a wall 2 ft. thick, was found to be about
+fifteen &frac12;-yd. batches per hour.</p>
+
+<p><i>Cracks in Walls and Longitudinal Reinforcement.</i>&mdash;Before the concrete
+walls were started, the contractor suggested using forms 100 ft.<span class='pagenum'><a name="Page_334" id="Page_334">[334]</a></span>
+long and building the walls in sections of that length; it was decided,
+however, to limit the length to 50 ft.</p>
+
+<p>The south walls, in sections approximately 50 ft. long, were built
+first, starting at Tenth Avenue and extending for about 500 ft. Soon
+after the forms were removed, irregular cracks appeared in the walls
+between the joints in practically every section. It was thought that
+these cracks might be due to the wall being very thin and being held
+at the back by the tie-rods; there was also quite a material change
+in the section of the wall at each drainage box. Although it was
+admitted that these cracks would have no effect on the stability of the
+wall, it was thought that, for appearance sake, it would be desirable
+to prevent or control them, if possible. The first method suggested
+was to shorten the sections to 25 ft., which would give an expansion
+and contraction joint every 25 ft., it being thought that sections of this
+length would not crack between the joints. This, however, was not
+considered desirable. An effort was then made to prevent cracks in a
+section of wall, about 46 ft. long, on the south side, by using longitudinal
+reinforcement. In the lower and upper face walls, &frac34;-in. square
+twisted steel rods were placed longitudinally about 4 in. in from the
+face and about 1 ft. 4 in. apart vertically. The sections of these walls
+were finished on April 10th, and May 5th, 1909, respectively. At
+present there are no indications of cracks in these sections, and they
+are practically the only ones in the south walls which do not show
+irregular cracks.</p>
+
+<p>It was decided, however, that, inasmuch as the cracks did not affect
+the stability of the walls, the increased cost of thus reinforcing the
+remaining walls was not warranted. An effort to control the cracks
+was made by placing corrugated-iron diaphragms in the form, dividing
+each 50-ft. section into three parts. The diaphragms were 1 ft. wide,
+and were placed with the outer edge 1 in. in from the face of the wall,
+but in the copings they were omitted. The purpose of these diaphragms
+was to provide weak sections in the walls, so that if there was any
+tendency to crack it would occur along the line of the diaphragms.
+Corrugated iron was used for the diaphragms instead of sheet iron as
+it was more easily maintained in a vertical position. The general
+arrangement of the diaphragms is shown on <a href="#plate52_fig4">Fig. 4, Plate LII</a>. The
+results obtained by using diaphragms have been quite satisfactory,
+and cracks approximately straight and vertical have usually appeared
+<span class='pagenum'><a name="Page_335" id="Page_335">[335]</a></span>opposite the diaphragms soon after the forms were removed. Diaphragms
+were used on all the remaining walls, with the exception of
+those between Stations 187 + 07 and 188 + 83 on the north side, where
+the rock was of poor character and bad slides had occurred. Between
+these points, in order to strengthen the wall, twisted steel rods, 1 in.
+square, were placed longitudinally, 6 in. in from the face of the wall
+and 2 ft. apart vertically, between Elevations 295 and 335.</p>
+
+<div class="figcenter" style="width: 458px;">
+<img id="plate52_fig1" src="images/p52f1.jpg" width="458" height="407"
+alt="Plate LII, Fig. 1.&mdash;Girders Under 9th Avenue Elevated Railroad."
+title="Plate LII, Fig. 1.&mdash;Girders Under 9th Avenue Elevated Railroad." />
+<span class="caption">Plate LII, Fig. 1.&mdash;Girders Under 9th Avenue Elevated Railroad.</span>
+</div>
+
+<div class="figcenter" style="width: 452px;">
+<img id="plate52_fig2" src="images/p52f2.jpg" width="452" height="576"
+alt="Plate LII, Fig. 2.&mdash; TW 100. P.T. &amp; T.R.R. Co. Terminal Station West. Showing excavation of completion of South abutment 9th Ave. and method of Supporting Elevated Railway Column 488. July 21, 09."
+title="Plate LII, Fig. 2.&mdash; TW 100. P.T. &amp; T.R.R. Co. Terminal Station West. Showing excavation of completion of South abutment 9th Ave. and method of Supporting Elevated Railway Column 488. July 21, 09." />
+<span class="caption">Plate LII, Fig. 2.&mdash; TW 100. P.T. &amp; T.R.R. Co. Terminal Station West. Showing excavation of completion of South abutment 9th Ave. and method of Supporting Elevated Railway Column 488. July 21, 09.</span>
+</div>
+
+<div class="figcenter" style="width: 450px;">
+<img id="plate52_fig3" src="images/p52f3.jpg" width="450" height="575"
+alt="Plate LII, Fig. 3.&mdash; TW 31. P.T. &amp; T.R.R. Co. Terminal Station West. View showing excavation 9th and 10th Avenues South of 32nd St. looking West from Sta. 184. Aug. 17, 07."
+title="Plate LII, Fig. 3.&mdash; TW 31. P.T. &amp; T.R.R. Co. Terminal Station West. View showing excavation 9th and 10th Avenues South of 32nd St. looking West from Sta. 184. Aug. 17, 07." />
+<span class="caption">Plate LII, Fig. 3.&mdash; TW 31. P.T. &amp; T.R.R. Co. Terminal Station West. View showing excavation 9th and 10th Avenues South of 32nd St. looking West from Sta. 184. Aug. 17, 07.</span>
+</div>
+
+<div class="figcenter" style="width: 450px;">
+<img id="plate52_fig4" src="images/p52f4.jpg" width="450" height="575"
+alt="Plate LII, Fig. 4.&mdash; TW 101. P.T. &amp; T.R.R. Co. Terminal Station West. Inside of concrete form for lower-face wall, showing drains, tie rods, diaphragms and methods employed for tying in the form in addition to braces outside. July 21, 09."
+title="Plate LII, Fig. 4.&mdash; TW 101. P.T. &amp; T.R.R. Co. Terminal Station West. Inside of concrete form for lower-face wall, showing drains, tie rods, diaphragms and methods employed for tying in the form in addition to braces outside. July 21, 09." />
+<span class="caption">Plate LII, Fig. 4.&mdash; TW 101. P.T. &amp; T.R.R. Co. Terminal Station West. Inside of concrete form for lower-face wall, showing drains, tie rods, diaphragms and methods employed for tying in the form in addition to braces outside. July 21, 09.</span>
+</div>
+
+<p><i>Tenth Avenue Portal.</i>&mdash;The design of the Tenth Avenue Portal
+is shown on <a href="#fig_09">Fig. 9</a>. The stone selected came from the Millstone Granite
+Company's Quarries, Millstone Point, Conn., and is a close-grained
+granite. <a href="#plate51_fig2">Fig. 2, Plate LI</a>, shows the completed portal.</p>
+
+<p>Practically all the stone cutting was done at the quarry, but certain
+stones in each course were sent long and were cut on the ground, in
+order to make proper closures. Drains were left behind the portal
+around the back of each arch, leading down to the bottom, and through
+the concrete base at each side of the portal and in the central core-wall;
+all these drains have been discharging water.</p>
+
+<p><i>Power-House.</i>&mdash;The old church at No. 236 West 34th Street, between
+Seventh and Eighth Avenues, was turned over to the New York Contracting
+Company-Pennsylvania Terminal for a power-house to supply
+compressed air for use on the Terminal Station work between Seventh
+and Ninth Avenues and the work below sub-grade as well as that on
+the Terminal Station-West. Four straight-line compressors and one
+cross-compound Corliss compressor were installed, the steam being supplied
+by three Stirling boilers. Three electrically-driven air compressors,
+using current at 6,600 volts, were also installed, and the total
+capacity of the power-house was about 19,000 cu. ft. of free air per
+minute compressed to 90 lb. per sq. in.</p>
+
+<p><i>Disposal Pier.</i>&mdash;The disposal pier (old No. 62 and new No. 72), at
+the foot of West 32d Street, North River, was leased by the Pennsylvania
+Railroad Company. The entire pier, with the exception of the
+piles, was taken down, and the piles which would be in the path of the
+proposed tunnel were withdrawn prior to the building of the tunnels
+and the construction of the pier for disposal purposes. Subsequent to
+the driving of the tunnels there was a considerable settlement in the
+pier, especially noticeable at the telphers, and finally these had to
+be abandoned on this account. <a href="#plate51_fig3">Fig. 3, Plate LI</a>, shows the chutes
+through which the earth was dumped on the decks of the scows
+<span class='pagenum'><a name="Page_337" id="Page_337">[337]</a></span>
+to form a padding on which to dump the heavier rock. <a href="#plate51_fig4">Fig. 4, Plate
+LI</a>, shows the derricks at the end of the pier. These were used, not
+only for loading heavy stones and skips, but also with a clam-shell
+bucket for bringing in broken stone and sand for use in the work.
+Large quantities of pipe, conduits, brick, etc., were also brought to this
+pier for use on the work.</p>
+
+<div id="Page_336" class="figcenter" style="width: 536px;">
+<a href ="images/fig09.png">
+<img id="fig_09" src="images/fig09tn.png" width="536" height="357" alt="PORTAL, RETAINING AND FACE WALLS, TENTH AVENUE" title="PORTAL, RETAINING AND FACE WALLS, TENTH AVENUE" />
+<span class="caption">Fig. 9.</span> (full page image)<br />
+PORTAL, RETAINING AND FACE WALLS, TENTH AVENUE
+</a>
+</div>
+
+
+<p class="sectionh">Organization of Engineering Force in Field.</p>
+
+<p>The design and execution of the work were under the direction of
+Charles M. Jacobs, M. Am. Soc. C.E., Chief Engineer, and James
+Forgie, M. Am. Soc. C.E., Chief Assistant Engineer. The writer
+acted as Resident Engineer.</p>
+
+<div class="figcenter" style="width: 617px;">
+<img id="fig_10" src="images/fig10.png" width="617" height="322" alt="Fig. 10" title="Fig. 10" />
+<span class="caption">Fig. 10</span>
+</div>
+
+<p>The general organization of the engineering force in the field is
+shown by the diagram, <a href="#fig_10">Fig. 10</a>.</p>
+
+<p>The position of Assistant Engineer, in responsible charge of Construction
+and Records, has been filled in turn by Messrs. A.W. Gill,
+N.C. McNeil, Jun. Am. Soc. C.E., and W.S. Greene, Assoc. M.
+Am. Soc. C.E.</p>
+
+<p>Messrs. A.P. Combes and T.B. Brogan have acted as Chief Inspector
+and Night Inspector, respectively, in charge of outside work
+during the entire carrying out of the contract.</p>
+
+<p>Base lines had been established on Ninth and Tenth Avenues for
+the Terminal work east of Ninth Avenue and for the Tunnel work
+<span class='pagenum'><a name="Page_338" id="Page_338">[338]</a></span>west of Tenth Avenue, and these lines, together with bench-marks
+similarly established, were used in laying out the Terminal Station-West
+work.</p>
+
+<p>Prior to the commencement of the work, elevations were taken on
+the surface at 10-ft. intervals, and elevations of the rock surface were
+taken on these points as the rock was uncovered. Cross-sections were
+made and used in computing the progress and final estimates.</p>
+
+<p>Very careful records were kept of labor, materials, derrick performances,
+steam-shovel performances, quantity of dynamite used, etc.,
+and, in addition, a diary was kept giving a description of the work and
+materials used each day; various tables and diagrams were also
+prepared.</p>
+
+<p>A daily report was sent to the Chief Office showing the quantities
+of excavation removed and concrete built, the force in the field, the
+plant at work, etc., during the previous day. At the end of each month
+a description of the work done during that month, with quantities,
+force of men employed, percentages of work done, etc., was sent to the
+Chief Office. Two diagrams, showing cross-sections and contours of
+the excavation done and the progress of the concrete walls, were
+also sent.</p>
+
+
+<p class="sectionh">Cost Account.</p>
+
+<p>From the records of labor and material obtained in the field, and
+from estimated charges for administration and power, an estimate
+was made of the cost to the contractor for doing various classes of
+work. It was necessary to estimate the administration and power
+charges, as the contractor's organization and power-house were also
+controlling and supplying power to the Terminal Station work east of
+Ninth Avenue and also the work below sub-grade. The labor and
+material charges in the field were placed directly against the class of
+work on which they were used and the administration and general
+charges (which included superintendence, lighting, etc.) were apportioned
+to the various classes of work in proportion to the value of the
+labor done.</p>
+
+
+<p class="sectionh">Statistics.</p>
+
+<p>The total weight of the structural steel used during the underpinning
+of Ninth Avenue was 1,475,000 lb.</p>
+
+<p>The total weight supported during the work under Ninth Avenue
+was about 5,000 tons.</p>
+
+<p><span class='pagenum'><a name="Page_339" id="Page_339">[339]</a></span></p><p>The average daily traffic over the Ninth Avenue Elevated Railway
+was 90,000 passengers, and, during the progress of the excavation and
+underpinning, about 100,000,000 passengers were carried over that
+structure.</p>
+
+<p>The total excavation was 521,000 cu. yd., of which 87% was solid
+rock.</p>
+
+<p>The average drill performance was about 33 lin. ft. per 8-hour
+shift.</p>
+
+<p>The average number of cubic yards of excavation per drill shift
+was 13.9.</p>
+
+<p>The average number of feet of drilling per cubic yard of excavation
+was about 2.4.</p>
+
+<p>The average excavation per pound of dynamite was 2.2 cu. yd.</p>
+
+<p>The average amount of excavation per derrick shift of ten hours,
+87% of the excavation being rock, was 50 cu. yd.</p>
+
+<p>The average derrick force per shift, including only foreman and
+laborers, was 13 men.</p>
+
+<p>The salaries of the engineering staff in the field and the expenses
+of equipping and maintaining the field office amounted to 2.8% of the
+cost of the work executed, 2.7% being for engineering salaries alone.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_A_1" id="Footnote_A_1"></a><a href="#FNanchor_A_1"><span class="label">[A]</span></a> Presented at the meeting of April 6th, 1910.</p></div>
+</div>
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Transactions of the American Society
+of Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
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+</body>
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+The Project Gutenberg EBook of Transactions of the American Society of
+Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910
+       The New York Tunnel Extension of the Pennsylvania Railroad
+       The Terminal Station - West
+
+Author: B.F.  Cresson, Jr
+
+Release Date: December 13, 2005 [EBook #17302]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SOCIETY OF CIVIL ENGINEERS ***
+
+
+
+
+Produced by Juliet Sutherland, Sigal Alon and the Online
+Distributed Proofreading Team at https://www.pgdp.net
+
+
+
+
+
+
+
+
+
+
+AMERICAN SOCIETY OF CIVIL ENGINEERS
+
+INSTITUTED 1852
+
+
+TRANSACTIONS
+
+Paper No. 1156
+
+
+THE NEW YORK TUNNEL EXTENSION OF THE
+PENNSYLVANIA RAILROAD.
+
+THE TERMINAL STATION-WEST.[A]
+
+BY B.F. CRESSON, JR., M. AM. SOC. C.E.
+
+
+
+
+_Location of Work._--The area covered by the work of the Terminal
+Station-West is bounded as follows: By the east line of Ninth Avenue; by
+the south side of 31st Street to a point about 200 ft. west of Ninth
+Avenue; by a line running parallel to Ninth Avenue and about 200 ft.
+therefrom, from the south side of 31st Street to the boundary line between
+the 31st and 32d Street properties; by this line to the east line of Tenth
+Avenue; by the east line of Tenth Avenue to the boundary line between the
+32d and 33d Street properties; by this line to the east line of Ninth
+Avenue. The area is approximately 6.3 acres.
+
+_House-Wrecking._--The property between Ninth and Tenth Avenues was covered
+with buildings, 94 in number, used as dwelling and apartment houses and
+church properties, and it was necessary to remove these before starting the
+construction. Most of the property was bought outright by the Railroad
+Company, but in some cases condemnation proceedings had to be instituted in
+order to acquire possession. In the case of the property of the Church of
+St. Michael, fronting on Ninth Avenue, 31st and 32d Streets, the Railroad
+Company agreed to purchase a plot of land on the south side of 34th Street,
+west of Ninth Avenue, and to erect thereon a church, rectory, convent, and
+school, to the satisfaction of the Church of St. Michael, to hand over
+these buildings in a completed condition, and to pay the cost of moving
+from the old to the new buildings, before the old properties would be
+turned over to the Railroad Company.
+
+The house-wrecking was done by well-known companies under contract with the
+Railroad Company. These companies took down the buildings and removed all
+the materials as far as to the level of the adjacent sidewalks. The
+building materials became the property of the contractors, who usually paid
+the Railroad Company for the privilege of doing the house-wrecking. The
+work was done between April and August, 1906, but the buildings of the
+Church of St. Michael were torn down between June and August, 1907.
+
+The bricks were cleaned and sold directly from the site, as were
+practically all the fixtures in the buildings. The stone fronts were broken
+up and left on the premises. Some of the beams were sold on the premises,
+but most of them were sent to the storage yards. Some of the lath and
+smaller timber was sold for firewood, but most of it was given away or
+burned on the premises.
+
+_Contracts and Agreements._--The main contract, awarded to the New York
+Contracting Company-Pennsylvania Terminal on April 28th, 1906, included
+about 502,000 cu. yd. of excavation (about 90% being rock), 17,820 cu. yd.
+of concrete walls, 1,320,000 lb. of structural steel, 638,000 ft., B.M., of
+framed timber, etc., etc.
+
+This contract was divided into two parts: "Work In and Under Ninth Avenue"
+and "Work Between Ninth and Tenth Avenues," and unit prices were quoted for
+the various classes of work in each of these divisions. The prices quoted
+for excavation included placing the material on scows supplied by the
+Railroad Company at the pier at the foot of West 32d Street, on the North
+River; there was a clause in the contract, however, by which the contractor
+could be required to make complete disposal of all excavated material at an
+additional unit price, and this clause was enforced on January 1st, 1909,
+when about 94% of the excavation had been done.
+
+For the purpose of disposing of the excavated material in the easterly
+portion of the Terminal, the New York Contracting Company-Pennsylvania
+Terminal had excavated under Ninth Avenue a cut which came to the grade of
+32d Street about midway between Ninth and Tenth Avenues, and a trestle was
+constructed from this point over Tenth Avenue and thence to the disposal
+pier at the foot of West 32d Street.
+
+On May 11th, 1906, the work of excavation was commenced on the east side of
+Ninth Avenue, and on July 9th, 1906, on the south side of 31st Street,
+between Ninth and Tenth Avenues. From the beginning, the excavation was
+carried on by day and night shifts, except on Sundays and holidays, until
+January, 1909, except that during the period from November, 1907, to
+October, 1908, the night shift was discontinued.
+
+_Geology._--The rock encountered may be classed as "gneiss"; its character
+varied from granite to mica schist. It was made up of quartz, feldspar, and
+mica, and there were also some isolated specimens of pyrites, hornblend,
+tourmaline, and serpentine. On the south side of the work, just west of
+Ninth Avenue, there were excellent examples of "contortions" of veins of
+quartz in the darker rock. On the east side of Ninth Avenue, near the north
+end of the work, glacial marks were found on the rock surface. The general
+direction of the stratification was north 5 deg. west, and the general incline
+about 60 deg. with the horizontal. As a rule, the rock broke sharply along the
+line of stratification. On the south side it broke better than on the north
+side, where it was usually softer and more likely to slide; and this,
+together with the fact that in winter it was subject to alternate freezing
+and thawing and in summer to the direct rays of the sun, made it rather
+difficult to get a good foundation for the retaining walls.
+
+
+WORK IN AND UNDER NINTH AVENUE.
+
+_General Description._--The work involved the excavation of about 375 ft.
+of the full width of Ninth Avenue to an average depth of about 58 ft., and
+the construction over this area of a steel viaduct, the deck of which was
+about 24 ft. below the surface, for the ultimate support of the Ninth
+Avenue structures.
+
+The following estimated quantities appear in the contract: Excavation of
+rock, 72,600 cu. yd.; excavation of all materials except rock, 9,300 cu.
+yd.; concrete (1:3:6) in abutments, etc., 1,680 cu. yd.; timber, 504,000
+ft., B.M.; structural steel, 1,320,000 lb., etc.
+
+While this excavation was being done it was necessary to support and
+maintain the three-track elevated railway structure of the Interborough
+Rapid Transit Company, of which 18 columns, or a length of about 340 ft.,
+were affected, the two-track surface railway structure of the New York City
+Railway Company, and various pipes, sewers, and conduits, and to maintain
+all surface vehicular and pedestrian traffic. All structures were left in
+place with the exception of the pipes, most of which were temporarily cut
+out. The 48-in. brick sewer in the center of Ninth Avenue was broken, and
+the sewage was pumped across the excavation through a smaller pipe.
+
+The general method adopted was as follows: The east and west sides of the
+avenue were closed, vehicular traffic was turned into the center, and a
+trestle for pedestrians was constructed west of the westerly elevated
+railway columns. All structures were then supported on transverse girders,
+running across the avenue, below the surface, and these rested on concrete
+piers on the central rock core. The sides of the avenue were then excavated
+to sub-grade, and the permanent steel viaduct was erected on both sides of
+the avenue as close as possible to the central rock core. The weight of all
+structures was then transferred to the permanent steel viaduct, erected on
+the sides of the avenue, by timber bents under the transverse girders
+resting on the permanent steel viaduct, and all weight was thus taken off
+the central rock core. This core was then excavated to sub-grade, the
+permanent viaduct was completed, and all structures were placed on its
+deck, using concrete piers and timber bents.
+
+The design and erection of the permanent steel viaduct and the permanent
+foundations on its deck were done under another contract, apart from the
+North River Division work, and are not described in this paper.
+
+_Elevated Railway Structure of the Interborough Rapid Transit
+Company._--The Ninth Avenue Elevated Railway was built between 1877 and
+1880 as a two-track structure, the design being such as to permit a third
+or central track to be added later, and this was built in 1894. It is
+supported on columns under the outside tracks, about 43 ft. from center to
+center longitudinally and 22 ft. 3 in. from center to center transversely,
+the central track being carried by transverse girders between the columns.
+
+The columns carrying the structure are of fan top design, with the points
+of bearing near the extremities at the top; each of the outside tracks is
+supported on two longitudinal latticed girders and the central track on
+two plate girders; between the columns, transverse girders are spliced to
+the outside track cross-frames, and carry the central track system. It was
+not thought desirable to put brackets on the columns near the street level
+to support the structure temporarily, and, as there is an expansion joint
+at each column, and as the transverse girders carrying the central track
+system are not rigidly attached to the longitudinal girders carrying the
+outside tracks, the central track could not be supported by supporting the
+outside tracks; therefore, independent supports for each track, in the form
+of overhead girders, had to be provided. The columns rest on brick piers,
+each having four 2-in. anchor-bolts. The brick foundations on the west side
+are wide in order to allow a 24-in. water main to pass directly beneath the
+columns. The foundations are usually on rock.
+
+[Illustration: PLATE XLVII, FIG. 1.--TW 4, P.N.Y. & L.I.R.R. Terminal
+Station West. View of 9th Ave. looking Northwest from 32nd Street, prior to
+commencement of work. April 23, 06.]
+
+[Illustration: PLATE XLVII, FIG. 2.--TW 17, P.N.Y. & L.I.R.R. Terminal
+Station West. View of East side of 9th Ave. looking North from a point 100
+feet south of 33rd St. showing condition of work. July 23, 06.]
+
+[Illustration: PLATE XLVII, FIG. 3.--TW 25, P.N.Y. & L.I.R.R. Terminal
+Station West. View showing permanent and temporary supports of 9th Ave.
+Structures, looking Northwest from 31st. St. April 24, 07.]
+
+[Illustration: PLATE XLVII, FIG. 4.--TW 28, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Avenue, North of 32nd St. looking West,
+showing rock excavation and supports of 9th Avenue structures. Aug. 17,
+07.]
+
+Fig. 1, Plate XLVII, shows the elevated railway structure and the street
+surface prior to the commencement of the work.
+
+The east track is used for north-bound local trains, the west track for
+south-bound local trains, and the central track for south-bound express
+trains between 7 and 9.30 A.M. and for north-bound express trains between
+2.30 and 7 P.M. It is said that an average of 90,000 passengers are carried
+over this structure every 24 hours.
+
+_Surface Railway Structure of the New York City Railway Company._--This is
+an electric surface railway of the ordinary type, the rail and slot being
+bedded in concrete, with cast-iron yokes every 5 ft. There are manholes
+every 100 ft., and cleaning-out holes every 15 ft. Power conduits are
+bedded in the concrete on the east side of the east track.
+
+_Forty-eight-Inch Brick Sewer._--This sewer was in the center of Ninth
+Avenue, with the invert about 12 ft. below the surface, and manholes about
+100 ft. apart, and had to be abandoned in this position to allow the
+transverse girders to be put in place to carry all structures while the
+excavation was being done.
+
+_Twenty-four-Inch Cast-Iron Water Main._--This water main was laid under
+the west elevated railway columns, with its top about 3 ft. below the
+surface, a space being left for it in the brick foundations, and a large
+column base casting being used to span it. Valves were installed, one north
+of 33d Street and one south of 31st Street, prior to excavating near the
+pipe, so that if it was broken the water could be shut off promptly.
+
+_Street Surface._--It was the original intention to close and excavate the
+east side of the avenue and to erect there a street-traffic trestle before
+closing the west side, but, at the contractor's request, both sides were
+closed, and all vehicular traffic was turned into the center. A light
+trestle on the west side of the avenue provided for pedestrian traffic.
+
+_Other Sub-surface Structures._--There were various gas mains, water mains,
+electric conduits, manholes, hydrants, etc., in the avenue, and most of
+these were cut out temporarily, at the contractor's request, to be replaced
+subsequently.
+
+_Supports for Elevated Railway Structure._--As stated previously, the
+central track had to be supported independently.
+
+The overhead girders, known as girders "B", were therefore designed as
+shown on Fig. 1, and put in place as shown on Figs. 2 and 3. The outside
+tracks were blocked directly on these girders, and the central track was
+supported by blocking up the transverse girders on I-beams placed between
+the girders "B"; and no blocking was placed between the girders "B" and the
+longitudinal girders carrying the central track. The weight on each column
+was assumed to be 172,000 lb.
+
+[Illustration: FIG. 1. (Full page image)
+
+DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES]
+
+_Supports for Surface Railway Structure._--A uniform load of 3,000 lb. per
+lin. ft. of single track, with the weight of a car at 39,000 lb., was
+assumed. Several feet of earth, between the structure and the rock, were
+mined out, and the structure was supported on I-beams and posts, and
+ultimately on the transverse girders by using timber bents under the
+I-beams, as shown on Fig. 3.
+
+_Water Mains and Sewer._--Cradles were designed for the support of the
+48-in. and 24-in. water mains, resting on the transverse girders, and the
+48-in. cast-iron sewer on the east side of the avenue was carried on
+I-beams bracketed to the ends of the transverse girders, as shown on Figs.
+1 and 2.
+
+[Illustration: FIG. 2. (Full page image)
+
+METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE]
+
+[Illustration: FIG. 3. (Full page image)
+
+METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO.]
+
+_Girders "C."_--The transverse girders below the street surface, referred
+to above, were known as girders "C," and they were put in place at first
+resting on concrete piers on the central core; the weight of all structures
+was placed on them while the sides of the avenue were being excavated, and
+the sides of the viaduct were being built. The ends of these girders were
+then picked up on the sides of the viaduct, and, spanning the central rock
+core, carried all structures while the core was being excavated and the
+viaduct completed. New foundations were then placed on the deck of the
+viaduct to carry all structures.
+
+Fifty-four of these girders were required, each weighing about 19,000 lb.
+The bents carrying the ends of these girders on the sides of the viaduct
+are shown on Fig. 2. They were of long-leaf yellow pine. These girders were
+located so that a cradle could be laid on them east of the elevated railway
+structure to carry a proposed 48-in. cast-iron water main.
+
+_Girders "B."_--Eighteen of these girders were required, each weighing
+about 6,000 lb. The timber bents supporting these girders, shown on Fig. 2,
+were of long-leaf yellow pine.
+
+The total weight, including the elevated railway structure, surface railway
+structure, pipes, etc., supported during the work, amounted to about 5,000
+tons.
+
+_Details of the Work._--The method in general is shown on Figs. 4 and 5. At
+first the east side of the avenue was closed and excavated down to rock,
+the earth was mined out under alternate yokes of the surface railway
+structure, and temporary posts were placed under the yokes to support the
+structure while the remainder of the earth was being removed. Then
+needle-beams and posts were placed under each yoke. The concrete forming
+the track structure was then enclosed with planking to prevent it from
+cracking and falling. I-beams were then placed under the needle-beams
+carrying the structures, and these were carried on posts; they were changed
+alternately until the excavation had been taken out to a depth of about 16
+ft. below the surface. In placing these I-beams, heavier blocking was used
+in the center of the span than at the ends where the bents would come, to
+prevent the subsidence of the track owing to the sag in the I-beams. As
+much excavation, to a depth of about 20 ft., was taken out adjoining the
+elevated railway foundations as could be done with safety. Fig. 2, Plate
+XLVII, shows this condition of the work. The 48-in. brick sewer was broken,
+and the sewage was pumped across the excavation.
+
+The overhead girders "B" were then put in place, and two of the girders "C"
+were used as temporary shoring girders at each column. These, as shown by
+Fig. 3, Plate XLVII, were placed parallel to the elevated railway, with
+blocking between them and the girders "B." Double bents, independent
+of each other, were placed under the ends of these temporary shoring
+girders, and these were braced securely to prevent possible dislodgment
+during the removal of the rock. The weight of the structure was then taken
+by jacking up the girders near the bents until the column was lifted off
+the old foundation; blocking was put in between the girders and the bents
+during the jacking, so that when the jacks were released the base of the
+column was still clear of the old foundation. One 80-ton jack was used for
+this purpose, and the general method is shown by Fig. 1, Plate LII.
+
+[Illustration: FIG. 4. (Full page image)
+
+METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES
+OF THE WORK]
+
+[Illustration: FIG. 5. (Full page image)
+
+METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK
+
+No. 1
+
+Condition Prior to Commencement of Work
+
+No. 2
+
+East side of Avenue cut down about 20 ft. Beams with Supporting Posts
+placed under Surface Railway Tracks. Girders _B_ and Temporary Shoring
+Girders _C_ for supporting Elevated Ry. in place.
+
+No. 3
+
+I's in place under Surface Ry. Tracks. Elevated Ry. carried on Temporary
+Shoring Girders, and Girders _C_ in place. 24" Water Main carried on Timber
+Cradle and sewage carried through Pipe _R_. Foot Walk carried on Girders
+_C_ in place on West Side of Avenue.
+
+No. 4
+
+Elevated Railway carried on Bents under Columns. Temporary Shoring Girders
+removed and Permanent Bents resting on Girders _C_ in place. Bents in place
+on Girders _C_ carrying Surface Railway. East and West sides of Avenue
+excavated down to Sub-Grade and Five rows of Permanent Steel in place on
+each side. Bents erected on Permanent Steel to catch ends of Girders _C_
+while 2 outside Concrete Piers are removed and 6th row of Permanent Steel
+on each side is put in place.
+
+No. 5
+
+Two outside Concrete Piers removed and 6th row of Permanent Steel in place.
+Girders _C_ carrying all structures now resting on Bents on Permanent
+Steel. 48" C.l. Sewer carried on Brackets on Girders _C_.
+
+No. 6
+
+Excavation Completed. ]
+
+Temporary raker braces were placed against the structure to prevent lateral
+movement. Four sets of these temporary shoring girders were used in this
+manner, two sets starting at the north end and two sets at about the middle
+of the work, and these sets were moved south as they were released.
+
+The columns being thus supported on temporary shoring girders, the old
+foundations were removed and the excavation was taken down to a level about
+16 ft. below the surface.
+
+Two sets of three of the girders "C" were then put in place under the
+avenue at each column, each set being placed on four concrete piers 6 ft.
+square with spaces of 4 ft. between them, so that the outside of the
+outside pier would be 18 ft. from the center of the avenue and 32 ft. from
+the house line. This is shown on Fig. 5 and on Fig. 3, Plate XLVII. Four
+small piers were used, as they could be more easily removed than one
+continuous pier. The girders "C" were set to line and grade, and the piers
+were built under them, great care being taken to get the concrete well
+under the girders so as to give a firm bearing.
+
+After these girders "C" were in place it was necessary to remove the
+temporary shoring girders before the bents could be erected on girders "C"
+to support girders "B," being in the same plane; and provision had to be
+made to support the structure while this was being done. Therefore, double
+bents were erected directly beneath the columns, as shown by Figs. 2, 4,
+and 5, and by Fig. 3, Plate XLVII. These were built with their sills
+resting on the girders "C," and blocking was put in between the sills and
+the rock to carry the full weight of the structure. Later, when the weight
+of the structure was carried on the permanent bents, this blocking was
+knocked out, but the bents were left in to carry the weight of the column
+itself, which was swinging more or less from the structure above. The
+weight of the structure was placed on these bents directly beneath the
+columns by jacking up the temporary girders again, putting blocking between
+the bents and the base of the columns, and taking out the blocking which
+had been put in previously under the temporary shoring girders. The 24-in.
+water main was carried over the excavation on cables from the temporary
+shoring girders, except when they were being jacked up, at which time posts
+were placed beneath it.
+
+Anchor-bolts were put in place between the column bases and the bents
+directly beneath, in order to increase the lateral stiffness, and raker
+braces were also used. This having been done, the temporary shoring girders
+were moved south to the next column, where the process was repeated. The
+timber bents, shown in detail by Fig. 2, were then put in place as shown by
+Figs. 4 and 5, and by Fig. 3, Plate XLVII. These bents were framed as
+tightly as possible, using generally a 20-ton jack, and they were erected
+simultaneously at each pair of columns. The weight was taken on these
+columns by jacking up directly beneath the column base and taking out the
+blocking between this base and the bent directly beneath the column. On
+releasing the jack the weight was transferred to the permanent timber
+bents, and the east and west columns of each pair were transferred on the
+same day. One 80-ton jack was used on the easterly columns and two were
+necessary on the westerly columns, one on each side of the 24-in. water
+main. The raker braces of these permanent bents were not framed as tightly
+as the main posts, in order that the main post should carry the entire
+weight and the raker braces merely steady the structure.
+
+Timber bents were erected on girders "C" to carry the I-beams under the
+surface railway structure, as shown on Fig. 3, and all temporary posts
+under these I-beams were removed. The bents were framed with a jack, as
+tightly as possible, and very little settlement of the track occurred.
+
+A cradle was then built under the 24-in. water main and placed on girders
+"C," and, as a temporary footwalk had been constructed on the west side of
+the avenue, it will be seen that all structures were thus carried on
+girders "C."
+
+All structures were put on the girders "C" before continuing the excavation
+on the sides of the avenue because, in case of a slide of rock, there would
+be less danger than to individual structures. The outside piers, on
+which the girders "C" rested, might even be lost, without affecting the
+stability of the structure, and posting could readily be done beneath these
+girders in case of necessity.
+
+A very careful record of levels, taken on the elevated railway columns, was
+kept, observations being made during each jacking up and at least twice a
+week during the progress of the work. The columns were usually kept about
+1/2 in. high so as to allow for compression in the timber bents.
+
+As a rule, no jacking of the elevated railway structure was done while
+trains were passing over, and trains were flagged during the operation.
+There was generally very little delay, as all jacking was done between
+10.30 A.M. and 2.30 P.M., when the traffic was lightest, and frequently the
+jacking was done between trains, causing no delay whatever. Steel clamps
+were placed, three on the top and three on the bottom of each set of the
+girders "C," to bind them together and cause them to act as a unit.
+
+All structures then being supported on girders "C," which were carried on
+four concrete piers resting on the central rock core, the excavation on the
+sides of the avenue was continued down to sub-grade and the east and west
+portions of the concrete north abutment were constructed. The central rock
+core was about 36 ft. wide on the top and 45 ft. wide on the bottom, and at
+the center of 32d Street it was about 42 ft. high.
+
+It was the original intention to excavate a sufficient width of the sides
+of the avenue to erect six rows of the permanent steel viaduct, 5 ft. from
+center to center, and this was done on the south portion of the work. On
+the north portion, however, the rock was of poor quality, and it was
+thought best to excavate for only five rows at first, to erect the five
+rows of permanent steel and put the timber bents in place under the ends of
+the girders "C," in order to give them some support while the outside
+concrete piers were being removed and the excavation was being widened out
+to permit the erection of the sixth row. Additional raker braces were put
+in these bents temporarily, and were removed when the sixth row of steel
+had been erected. This is shown on Figs. 4 and 5.
+
+[Illustration: PLATE XLVIII, FIG. 1.--TW 33, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Ave. looking North from 31st St., showing
+rock excavation and supports of 9th Ave. structures. Dec. 28, 07.]
+
+[Illustration: PLATE XLVIII, FIG. 2.--TW 39, P.T. & T.R.R. Co. Terminal
+Station West. East side of 9th Ave. looking North from 31st Street, showing
+rock excavation and permanent steel work. March 24, 08.]
+
+[Illustration: PLATE XLVIII, FIG. 3.--TW 73, P.T. & T.R.R. Co. Terminal
+Station West. West side of Ninth Ave. Jacking up girders "C" at Elevated
+Railroad Column 491, showing method of taking weight on permanent viaduct
+girders. Nov. 14, 08.]
+
+[Illustration: PLATE XLVIII, FIG. 4.--TW 58, P.T. & T.R.R. Co. Terminal
+Station West. East side of Ninth Ave. looking North from 31st St., showing
+underpinning of Ninth Ave. Structures. Aug. 10, 08.]
+
+Fig. 4, Plate XLVII, and Fig. 1, Plate XLVIII, show the structures
+supported on the central rock core and the excavation on the east side to
+permit of the erection of the permanent viaduct girders. Fig. 1, Plate
+XLVIII, shows also the easterly portion of the concrete north abutment.
+Fig. 2, Plate XLVIII, shows five rows of the permanent viaduct girders
+erected on the east side of the work.
+
+The excavation of the sides of the avenue having been completed, and six
+rows of permanent viaduct girders erected on both sides, timber bents, as
+shown on Figs. 2, 4, 5, and 6, were erected on this steel to support the
+ends of the girders "C" and carry the structure while the rock core was
+being excavated. Fig. 3, Plate XLVIII, shows the method of taking the
+weight on these bents. Four 80-ton jacks were used, and oak blocks were
+placed on the top of each jack to transmit pressure to a temporary oak cap
+under the girders "C" independent of the bents; all four of these jacks
+were operated simultaneously, and the girders "C" were lifted off the bents
+and clear of the concrete piers. Oak filling pieces were then inserted
+between the bents and the girders "C," so that when the jacks were released
+the girders "C" were clear of the concrete piers. Fig. 3, Plate XLVIII,
+shows that the girders have been lifted off the piers. Elevations were
+taken on each set of girders during each operation, and careful
+observations were made on the elevated railway columns. Where the rock was
+very close to these bents, the open space between the posts was filled with
+blocking so that there would be less danger of the bent shifting if struck
+by blasted materials. Fig. 3, Plate XLVIII, shows one of these bents filled
+with blocking.
+
+All structures being carried on girders "C," which, in turn, were carried
+on the sides of the permanent viaduct, the central core was excavated. Fig.
+4, Plate XLVIII, and Figs. 1, 2, 3, and 4, Plate XLIX, show various views
+of the work at this stage.
+
+The central portion of the viaduct was then erected, and, using concrete
+piers and timber bents, all structures were placed on its deck. Fig. 3,
+Plate XLIX, shows the piers under the elevated railway columns prior to the
+removal of girders "C."
+
+[Illustration: FIG. 6. (Full page image)
+
+GENERAL ARRANGEMENT OF TEMPORARY AND PERMANENT STRUCTURES]
+
+During the latter part of 1908 a 48-in. cast-iron water main was laid by
+the city on a cradle built by the Railroad Company on girders "C" on the
+east side of the avenue. This is part of the high-pressure system, and the
+location and elevation of this water main were taken into consideration
+when the underpinning was designed. This main, and the 48-in. cast-iron
+sewer bracketed to girders "C," are shown on Fig. 4, Plate XLVIII.
+
+Elevations had been taken on marks on the elevated railway columns
+between 30th and 34th Streets at the time the original surveys were made,
+in 1902, and these marks were used to test the level of the structure
+during the progress of the excavation.
+
+At the extreme south end of the work the procedure was changed. The east
+side was excavated down to sub-grade, the east portion of the south
+abutment was constructed, and six rows of the permanent steel viaduct were
+erected. Very little excavation had been done on the west side of the
+avenue at the south end of the work, and it would have delayed the
+completion of the work to have waited for the excavation for and the
+construction of the west portion of the south abutment and the erection of
+the steel; therefore, instead of supporting the girders "C" on the central
+rock core, the east ends were taken up on the permanent viaduct girders,
+and the west ends were supported on a concrete pier on the rock. The
+central portion of the avenue was excavated in advance of the west portion.
+The permanent viaduct girders were put in place from east to west across
+the avenue, and the girders "C" were supported on the deck of the permanent
+viaduct approximately under the west elevated railway columns before the
+west portion of the avenue was excavated, the central portion of the south
+abutment having been constructed before the west portion. This procedure
+was adopted only at the north girders "C" at elevated railway column No.
+488, the south set of girders "C" being on the rock immediately south of
+the south abutment. Figs. 2 and 4, Plate XLIX, and Fig. 2, Plate LII, show
+various stages of the work at the south end.
+
+[Illustration: PLATE XLIX, FIG. 1.--TW 60, P.T. & T.R.R. Co. Terminal
+Station West. Under Ninth Ave., looking South from North abutment, showing
+underpinning and excavation of rock core. Aug. 13, 08.]
+
+[Illustration: PLATE XLIX, FIG. 2.--TW 84, P.T. & T.R.R. Co. Terminal
+Station West. View looking toward Ninth Ave. from South side of 31st St.,
+200 feet West of Ninth Ave. Jan. 28, 09.]
+
+[Illustration: PLATE XLIX, FIG. 3.--TW 88, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. Center line of 32nd St., looking East from Sta.
+183+50, showing excavation under Ninth Avenue, permanent concrete piers
+under Elevated Railway Columns and removal of temporary shoring girders
+"C". April 8, 09.]
+
+[Illustration: PLATE XLIX, FIG. 4.--TW 95, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. View under Ninth Avenue looking Southward from 100
+feet South of center line, showing underpinning of Ninth Avenue structure
+taken at sub-grade. May 25, 09.]
+
+It was made a practice all through the work to transfer the weight of the
+structures very positively from one support to another by lifting them
+bodily by jacks, and putting in filler pieces before releasing the jacks,
+not trusting to wedging to transfer the loads. In fact, apart from the
+boxing-in of the surface railway concrete, no wedges whatever were used.
+This appears to have been a decided advantage, for, with the constant
+pounding of trains on the elevated railway and the jarring due to heavy
+trucks on the pavement blocks, it is very likely that wedging would have
+become loosened and displaced, whereas, with blocking, there was little or
+no tendency toward displacement due to vibration. Although the vibration of
+the structure, when a long length was supported on girders "C" resting on
+the permanent viaduct girders on the sides of the avenue, appeared to be
+considerable, not only vertically but transversely, very careful
+observation showed that the sag in the girder "C" due a live load of three
+elevated railway trains, one surface railway car, and one heavy truck,
+amounted to 1/8 in. The sideway vibration did not amount to more than 1/32
+in. on either side of the normal position. More vibration was caused by
+heavy trucks and wagons going over the stone pavement than by the elevated
+railway trains or surface cars.
+
+No blasting was done near the supports of the elevated railway structure
+while trains were passing over it, and occasionally trains were stopped
+during a heavy or uncertain blast. A watchman on the surface, day and
+night, and at first one and later two flagmen on the elevated railway
+structure, were on duty at all times, reporting to the Interborough Rapid
+Transit Company, by whom they were employed. Log mats and timber protection
+for the girders and the columns of the permanent viaduct were used, as
+shown by Figs. 1 and 4, Plate XLIX, during the excavation of the rock core,
+and timber was also used to protect the face of the completed portions of
+the concrete abutments.
+
+In excavating the sides of the avenue, the rock broke better on the east
+than on the west side, where large seams developed and some slides
+occurred.
+
+_Abutments._--As shown on Fig. 7, the face of the north abutment has a
+batter of 2 in. to the foot, and the face of the south abutment has a
+variable batter, the base being on a grade and the bridge seat being level,
+and both maintaining a uniform distance from the center of the Terminal
+Yard. The back walls of the abutments were not built until the steel had
+been put in place.
+
+No attempt was made to water-proof these abutments, but, in the rear of the
+wall, open spaces were left, about 6 ft. from center to center, which were
+connected with drain pipes at the base of and extending through the wall,
+for the purpose of carrying off any water that might develop in the rock.
+These drains were formed by building wooden boxes with the side toward the
+rock open and the joints in the boxes and against the rock plastered with
+mortar in advance of the wall. A hose was used to run water through these
+drains during the placing of the concrete, for the purpose of washing out
+any grout which might run into them. Each box was washed out at frequent
+intervals, and there was no clogging of the drains whatever. This method
+of keeping the drains open was adopted and used successfully for the entire
+work. The abutments were built of concrete, and the mixture was 1 part of
+cement, 3 parts of sand, and 6 parts of broken stone.
+
+The concrete was mixed in a No. 3 Ransome mixer, and was placed very wet.
+No facing mixture or facing diaphragms were used, but the stone was spaded
+away from the face of the wall as the concrete was laid. Chutes were used
+inside the form, if the concrete had to drop some distance. Work was
+continued day and night, without any intermission, from the time of
+commencement to the time of completion of each section.
+
+The face of the concrete wall was rubbed and finished in a manner similar
+to that used on the walls between Ninth and Tenth Avenues, as described
+later.
+
+Fig. 2, Plate LII, shows the east and central portions of the south
+abutment, completed and carrying the permanent viaduct, and the excavation
+completed for the west portion.
+
+
+WORK BETWEEN NINTH AND TENTH AVENUES.
+
+_General Description._--The work involved the excavation of about 5.4
+acres, between the west house line of Ninth Avenue and the east house line
+of Tenth Avenue, to an average depth of about 50 ft., the construction of a
+stone masonry portal at Tenth Avenue leading to the River Tunnels, and the
+construction around the site of the concrete retaining and face walls.
+
+The following estimated quantities appear in the contract: Excavation of
+rock in trenches, 3,400 cu. yd.; excavation of rock in pit, 377,000 cu.
+yd.; excavation of all materials except rock in trenches, 6,500 cu. yd.;
+excavation of all materials except rock in pit, 34,000 cu. yd.; concrete,
+1:3:6, in retaining walls, 4,580 cu. yd.; concrete, 1:3:6, in face walls,
+7,460 cu. yd.; concrete, 1:2:3, with 3/4-in. stone, in face walls, 4,100
+cu. yd.; stone masonry in portal, 247 cu. yd., etc., etc.
+
+[Illustration: Fig. 7. (Full page image)
+
+NINTH AVE. ABUTMENTS & KEY PLAN]
+
+As previously stated, the contract price included the placing of all
+excavated material on scows at Pier 62, North River. Prior to this contract
+this pier had been used by the New York Contracting Company-Pennsylvania
+Terminal, for the disposal of excavated material from east of Ninth
+Avenue. In order to get the material to the pier, the contractor had
+excavated a cut under Ninth Avenue which came to the grade of 32d Street
+about midway between Ninth and Tenth Avenues, and a trestle was constructed
+from this point over Tenth Avenue and thence to the pier. Fig. 2, Plate
+XLVII, shows the east end of this cut, and Fig. 1, Plate L, shows the
+trestle, looking east from Tenth Avenue.
+
+A 30-ton steam shovel was brought to the south side of the work, and
+commenced operating on July 9th, 1906. After working there about a month,
+the earth had been practically stripped off the rock, and the shovel was
+moved over to the north side where it excavated both earth and rock until
+August 10th, 1907.
+
+At three points south of 32d Street and at one point north of 32d Street
+near Tenth Avenue, cuts were made in the rock to sub-grade, and from these
+cuts, together with the cuts on the west side of Ninth Avenue, all widening
+out was done and the excavation was completed. Fig. 1, Plate L, shows the
+excavation of the three cuts on the south side of 32d Street, the steam
+shovel operating on the north side of that street, and the
+material-disposal tracks and trestle. Fig. 3, Plate LII, shows the cuts
+joined up and the excavation along the south side practically completed.
+
+On the north side of the work, between Stations 182 + 90 and 183 + 65, the
+rock was low, and provision had to be made for maintaining the yards to the
+north of the site. Therefore a rubble-masonry retaining wall was built,
+with the face about 2 ft. north of the face of the proposed concrete wall
+which was to be put in later. On the same side of the work, between
+Stations 188 + 24 and 188 + 46, the rock was exceedingly poor, and as a
+small frame house on the adjoining lot was considered to be in an unsafe
+condition, a rubble masonry retaining wall was built. As the building
+adjoining the south side of the work at Tenth Avenue was on an earth
+foundation, it was necessary to underpin it before the excavation could be
+done. The building was supported on needles, and rubble masonry was put in
+from the bottom of the old foundation to the rock. The foundation of 413
+West 31st Street, immediately west of the Express Building site, was of
+very poor masonry, and it was necessary to rebuild it prior to taking out
+the adjoining excavation.
+
+[Illustration: PLATE L, FIG. 1.--TW 23, P.N.Y. & L.I.R.R. Terminal Station
+West. View looking Eastward from Tenth Ave., showing work between Ninth &
+Tenth Avenues. Dec. 26, 06.]
+
+[Illustration: PLATE L, FIG. 2.--TW 35, P.T. & T.R.R. Co. Terminal Station
+West. View looking Northwest from Sta. 184, 120 feet South of center line.
+Dec. 31, 07.]
+
+[Illustration: PLATE L, FIG. 3.--TW 96, P.T. & T.R.R. Co. N.R. Div.
+Terminal Station West. View looking West from Ninth Avenue Elevated
+Railway, showing condition of work. May 26, 09.]
+
+[Illustration: PLATE L, FIG. 4.--TW 104, P.N.Y. & L.I.R.R. Terminal Station
+West. View from Tenth Avenue looking East, showing progress of concrete
+walls. Aug. 7, 09.]
+
+Along the north side, between Stations 186 + 50 and 187 + 50, the walls
+supporting the adjoining back yards were of poor quality and had to be
+renewed by the contractor before excavation could be done.
+
+The excavated material was loaded by derricks on cars at the top of the
+excavation, these cars being on tracks having a direct connection with the
+disposal trestle, as shown by Fig. 1, Plate L. As soon as it could be done,
+derricks were placed at the bottom of the excavation; tracks were then laid
+out there, and the excavated material was loaded on cars at the bottom and
+hoisted by derricks to cars on the disposal trestle. A locomotive was
+lowered to the bottom of the excavation on August 25th, 1907, and a derrick
+started operating at the bottom on August 27th, 1907. The commencement of
+this work by derricks at the bottom is shown by Fig. 3, Plate LII. In
+general, the disposal tracks were maintained about on the center line of
+31st Street until the excavation had been carried as close to them as
+possible, and on October 16th, 1907, they were shifted to the extreme north
+side of the work, as shown by Fig. 2, Plate L. A portion of the old trestle
+was left in place near Tenth Avenue, a derrick was erected thereon, and the
+tracks were used for cars to receive the excavated material hoisted from
+sub-grade. The disposal trestle was maintained in this position until such
+time as it would interfere with the excavation, and then the tracks were
+abandoned. This was done on November 11th, 1908. Fig. 3, Plate L, shows the
+finishing of the excavation on the north side of the work. On August 30th,
+1908, a cut was made under Ninth Avenue at sub-grade, and cars could then
+be run from Seventh to Tenth Avenue at sub-grade. On October 24th, 1908,
+the connection with the disposal trestle east of Ninth Avenue was
+abandoned, and all excavated material was hoisted from sub-grade at Tenth
+Avenue by derricks.
+
+As previously stated, the contractor was required to make complete disposal
+of all excavated material after January 1st, 1909, but was allowed the use
+of the pier until January 20th, 1909, after which date the materials were
+hoisted by derricks at Tenth Avenue, loaded on 2-horse trucks, and
+transported to the 30th Street pier, North River, where it was loaded on
+scows by two electric derricks. A considerable amount of the rock
+excavation was broken up and used for back-fill.
+
+_Earth Excavation._--Practically all the earth excavation, amounting to
+about 57,000 cu, yd., was done with steam shovels. The average quantity of
+earth excavated by a steam shovel per 10-hour shift was 180 cu. yd. This
+material was loaded on side-dump cars and taken to the disposal pier where
+it was dumped through chutes to the decks of scows. Inasmuch as the
+quantity of earth excavation was small, as compared with the rock, the
+earth was used principally for the first layer on the scows for padding, so
+that small stones might be dumped through the chutes without injuring the
+decks.
+
+_Rock Excavation._--As previously stated, the rock broke better on the
+south than on the north side, where there were several slides, and
+considerable excavation had to be taken out beyond the neat line required
+in the specifications. The worst slide occurred at midnight on July 3d,
+1909, at about Station 188 + 50. The last blast, to complete the excavation
+to sub-grade at this point, had been fired in the afternoon of the same
+day, and the mucking was practically completed. Great care had been taken
+in excavating near this point, as it was evident that the rock was not of a
+very stable character, but, when the excavation had been completed, it was
+thought that the rock remaining in place would stand. The volume of
+material brought down by this slide amounted to about 200 cu. yd. The rock
+on the south side broke very well, and there were no slides of any
+consequence.
+
+The drill holes were laid out by the blaster, and the general method of
+drilling for different classes of work was as follows: In breaking down,
+the holes were started about 8 ft. apart, on a slight batter, so that at
+the bottom they would be considerably less than 8 ft. apart. They were
+drilled about 10 ft. deep, and blasting logs were used, as it was necessary
+to load quite heavily in order to lift the material and start the cut.
+After the cut had been made, side holes were shot to widen out sufficiently
+to start another cut.
+
+After a side cut about 20 ft. deep had been made, the side holes were
+drilled 20 ft. deep, and the holes were loaded and tamped for the full
+20-ft. cut. Under the terms of the specifications, the contractor was
+required to complete the excavation on the sides by drilling broaching
+holes.
+
+The maximum length of drill steel was about 20 ft., and, where the
+excavation plane of broaching was more than 20 ft. in depth, the contractor
+was permitted to start the holes back of the broaching line, in order to
+allow for setting up the drills on the second lift. A distance of about 8
+in. was usually allowed for setting up a drill. The broaching line was
+painted on the surface of the rock in advance of the drilling, and the
+batter of the drill was tested with a specially designed hand-level in
+which the bubble came to a central position when the face of the level was
+on the required batter. Holes were also drilled in front of this broaching
+line, and, when the excavation had been taken out to within about 6 ft. in
+front of it, the holes immediately in front were loaded, and also about
+every third one of the broaching holes, and, unless the rock was very bad,
+it usually broke sharply at the broaching line. Occasionally, the broaching
+holes which were not loaded were filled with sand, which gave rather better
+results than leaving them open.
+
+In the steam-shovel work on the east side of Ninth Avenue, spring holes
+were used. They were formed by drilling a 20-ft. hole and exploding at the
+bottom of it, without tamping, two or three sticks of dynamite, and
+repeating this process with heavier charges until there had been formed at
+the bottom of the hole a large cavity which would hold from 100 to 200 lb.
+of dynamite. Face holes and breast holes were also drilled, and it was
+possible by this method to drill and break up a cut 20 ft. deep and 15 ft.
+thick. The only place where spring holes were used on this work was on the
+east side of Ninth Avenue where the heavy cutting was sometimes extended
+beyond the east house line.
+
+From the best records obtainable, the average progress in drilling was
+about 33 lin. ft. per 8-hour shift. The average number of cubic yards of
+excavation per drill shift was 13.9, and the average amount of drilling per
+cubic yard of excavation was 2.4 ft.; this covered more than 27,000 drill
+shifts.
+
+The dynamite was practically all 60%, and the average excavation per pound
+of dynamite was 2.2 cu. yd. The contractor employed an inspector of
+batteries and fuses, who, using an instrument for that purpose, tested the
+wiring of each blast prior to firing, in order to discover any short
+circuits, and thus prevent the danger of leaving unexploded dynamite in the
+holes.
+
+The average quantity of excavation per derrick shift of 10 hours, covering
+7,400 shifts, 87% of the excavation being rock, was 50 cu. yd., and the
+average force per shift, including only foreman and laborers, was 13 men.
+It was found that a derrick operating at the top of a 20-ft. cut would
+handle about 40 cu. yd. per shift, whereas, if operating at the bottom of
+the cut, it would handle about 60 cu. yd. per shift. The elevator derricks
+at Tenth Avenue were very efficient, and each could take care of the
+material from four derricks at the bottom, hoisting 250 cu. yd. per shift a
+height of 60 ft.
+
+_Concrete Retaining and Face Walls._--It was essential to have the greatest
+space possible at the bottom of the excavation, and, inasmuch as the yard
+was to be left open, it was necessary to provide some facing for the rock
+on the sides in order to prevent disintegration, due to exposure, and give
+a finished appearance to the work. Above the rock surface a retaining wall
+of gravity section was designed, the top being slightly higher than the
+yards of the adjoining properties. The face wall was designed to be as thin
+as possible, in order to allow the maximum space for tracks.
+
+The excavation, therefore, was laid out so that the back of the retaining
+wall would not encroach on the adjoining property, but would practically
+coincide with the property line at positions of maximum depth.
+
+The batter on the face of the wall was 2 in. per ft., and a bridge seat
+3-1/2 ft. wide was formed at an elevation of 22 ft., minimum clearance,
+above the top of the rail. This bridge seat was made level. The maximum
+height of the south wall is 49 ft., and of the north wall 65 ft.
+
+The face walls were classed as "Upper Face Walls," extending from the base
+of the retaining wall to the bridge seat, and as "Lower Face Walls,"
+extending from the bridge seat to the base of the wall. The general design
+is shown on Fig. 8.
+
+In considering the design of the face wall it was felt that, the wall being
+so thin, ample provision should be made to prevent any accumulation of
+water and consequent pressure back of the wall; therefore, no attempt was
+made to water-proof it, but provision was made to carry off any water which
+might appear in the rock. Box drains, 2 ft. wide and 6 ft. from center to
+center, were placed against the rock, so that, there being but 4 ft.
+between the drains, and the wall having a minimum thickness of 2 ft., any
+water in the rock would not have to go more than 2 ft. to reach a drain,
+and would probably pass along the face of the rock to a drain rather than
+through 2 ft. of concrete. These drains were connected with pipes leading
+through the wall at its base.
+
+[Illustration: FIG. 8. (Full page image)
+
+RETAINING AND FACE WALLS NORTH SIDE]
+
+These box drains occurred so frequently, and decreased the section of the
+wall so materially, that it was thought desirable to tie the wall to the
+rock. This was done by drilling into the rock holes from 6 to 15 ft. in
+depth, and grouting into each hole a 1-1/2-in. rod having a split end and a
+steel wedge. The outer end of each rod was fitted with a 12 by 12 by
+1/2-in. plate and a nut, and extended into the wall, thus tying the
+concrete securely to the rock. The drains being 6 ft. from center to
+center, the tie-rods were placed midway between them, and 6 ft., from
+center to center, vertically and horizontally. Fig. 8 shows the arrangement
+of these rods and drains. Around the Express Building site, just west of
+Ninth Avenue, on the south side of the work, the bridge seat was omitted,
+and the face wall was designed 2 ft. thick from top to bottom. The batter
+on the 31st Street wall was made variable, the top and bottom being
+constant distances from the center line and on different grades.
+
+The retaining walls were water-proofed with three layers of felt and
+coal-tar pitch, which was protected by 4 in. of brick masonry. A 6-in.
+vitrified drain pipe was laid along the back of the wall, with the joints
+open on the lower half, and this was covered with 1 ft. of broken stone and
+sand before any back-fill was placed on it.
+
+The arrangement of the drains was as follows: The 6-in. drain back of the
+retaining wall was connected with one of the box drains in the rear of the
+face wall by a cast-iron pipe or wooden box every 24 ft., and this ran
+through the base of the retaining wall. Midway between these pipes, a
+connection was made at the bridge seat between the drain in the rear of the
+face wall and the gutter formed at the rear of the bridge seat to carry off
+rain-water coming down the face of the wall above. All the box drains,
+except those connected with the drains back of the retaining wall, were
+sealed at the elevation of the base of the retaining wall, as noted
+previously.
+
+The specifications required vitrified pipe to be laid through the retaining
+wall, but, owing to the difficulty of holding the short lengths of pipe in
+place during the laying of wet concrete, they were dispensed with, and
+either iron pipes or wooden boxes were used.
+
+_Tie-Rods._--When the excavation on the sides had been completed, movable
+drilling platforms were erected, as shown by Fig. 4, Plate L. The holes
+were drilled on a pitch of 2 in. per ft. with the horizontal. The depths of
+the holes were decided by the engineer, and were on the basis of a minimum
+depth of 5 ft. in perfect rock; the character of the rock, therefore, and
+the presence of seams, determined the depths of the holes. Each hole was
+partly filled with grout, and the rod, with the steel wedge in the split
+end, was inserted and driven with a sledge so that the wedge, striking the
+bottom of the hole first, would cause the split end of the rod to open.
+Each hole was then entirely filled with neat cement grout.
+
+_Box Drains._--Various methods of forming the box drains were considered,
+such as using half-tile drains, or a metal form, or a collapsible form
+which could be withdrawn, but it was finally decided to build boxes in
+which the side toward the rock was open and the joints in the boxes and
+against the rock were plastered with cement mortar. These boxes were left
+in place. Fig. 1, Plate LI, shows the tie-rods and box drains in place, and
+holes being cut near the bottom of the drains for the pipes leading through
+the wall.
+
+_Forms._--Fig. 1, Plate LI, shows the form used on the south side of the
+work. The materials were of good quality, and the form, which was about 50
+ft. long, was used to build twelve sections, or about 600 ft. of wall. The
+form was tied in at the top and bottom by cables attached to rods drilled
+into the rock, and it was thought that, with the trusses to stiffen the
+middle section of the form, it would not be necessary to use raker braces
+against it. This would have been desirable, as the placing of the raker
+braces took considerable time. It was found, however, that the form was not
+sufficiently rigid, as it bulged at the middle section and could not be
+held by the trusses. Two or three sets of raker braces, about 12 ft. apart,
+were used, and in addition, rods with turnbuckles were placed through the
+form and fastened to the tie-rods, and thus the form was held in place
+successfully. On the forms built later, the trusses were omitted, and raker
+braces, about every 6 ft., were used. The rods which screwed into the
+turnbuckles were removed before the form was moved. The photograph, Fig. 4,
+Plate LII, was taken inside the concrete form for the lower face wall on
+the north side, and shows the drains leading through the wall, the
+turnbuckles attached to the tie-rods, the cables attached to rods in the
+rock, and the braces to keep the form from coming in; these braces, of
+course, were removed as the concrete came up. The form was built low and
+wedged up into position. After a section of concrete had set sufficiently,
+the wedges were knocked out, the form was lowered and moved from the wall,
+and was then moved along the lowest waling piece by block and tackle to its
+new position.
+
+Fig. 4, Plate L, shows the forms used on the north side of the work.
+
+A section, 1 ft. square, at the top of the bridge seat of the lower face
+wall, was left out, so that the bottom of the form for the upper face wall
+could be braced against it. The top of this form was tied by cables
+attached to rods in the rock and by rods with turnbuckles running from back
+to front of the form; braces were also put in from the back of the
+retaining wall form to the walls of buildings along the property lines,
+when this could be done. The middle section of the form was held by rods
+with turnbuckles which passed through the form and were fastened to each of
+the tie-rods drilled into the rock, as was also done in the case of the
+lower face wall. It was generally possible to hold the form to true
+position in this manner, but occasionally it had a tendency to bulge; when
+this occurred, the rods leading through the form and fastened to the
+tie-rods were tightened up, the placing of the concrete was slowed up, and
+no serious bulging occurred.
+
+Bulkheads at the ends of the sections were built of rough planking securely
+braced to the rock, except that a planed board was laid up against the face
+of the form to make a straight joint. At the end of each section a V was
+formed, as shown by Fig. 1, Plate LI. At all corners, a "return," or
+portion of the wall running at right angles, was built, and no section of
+wall was stopped at a corner.
+
+_Filling Forms of Lower Face Walls._--A temporary trestle was erected above
+the elevation of the bridge seat, and a track, leading from the mixer to
+the form to be filled, was laid on it. At the commencement of each section
+a layer of mortar (1 part of cement to 2-1/2 parts of sand) was deposited
+on the bottom. A 1:3:6 mixture of concrete was used; it was run from the
+mixer into dump-cars and deposited in the form through chutes, three of
+which were provided for each 50-ft. section, the average length. The
+concrete was mixed wet, and was not rammed; the stone was spaded back from
+the face, and no facing mixture or facing diaphragms were used. Work on
+each section was continued day and night without any intermission from the
+time of commencement to the time of completion. At frequent intervals the
+box drains were washed out thoroughly with a hose, in order to prevent them
+from clogging up with grout.
+
+[Illustration: PLATE LI, FIG. 1.--TW 66, P.N.Y. & L.I.R.R. Terminal Station
+West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17,
+08.]
+
+[Illustration: PLATE LI, FIG. 2.]
+
+[Illustration: PLATE LI, FIG. 3.--P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy.
+West. Disposal trestle just before demolition. View of South side showing
+chutes. Jan. 21, 09.]
+
+[Illustration: PLATE LI, FIG. 4.--A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy.
+West & Oj. View across North River on line of Tunnels, looking from New
+York to New Jersey. Feb. 9, 07.]
+
+In the first few sections of wall, the form was filled to within 1 in. of
+the top of the bridge seat and allowed to set for about 2 hours; it was
+then finished to the proper elevation with a plaster of 1 part of cement to
+1 part of sand. This did not prove satisfactory, as there were indications
+of checking and cracking, and, later, the form was filled to the required
+elevation and the surface floated. The form was allowed to remain in place
+for from 18 to 24 hours, depending on the weather. In most cases,
+immediately after the form had been moved, a scaffold was erected against
+the face of the wall, and the face was wet and thoroughly rubbed, first
+with a wooden float and then with a cement brick, until the surface was
+smooth and uniform.
+
+The section 1 ft. square at the top of the bridge seat, which was left out
+in order to brace the bottom of the form for the upper face wall, was
+filled in after the walls had been completed. The old concrete was very
+thoroughly cleaned before the new concrete was placed on it, and a gutter
+was formed at the rear connecting with the box drains back of the wall to
+carry off rain-water coming down the face of the upper walls.
+
+In hot weather the walls were thoroughly wetted down several times a day
+for several days after the form had been removed.
+
+_Upper Face and Retaining Wall._--In cases where the top of the retaining
+wall was at a higher elevation than the mixer, it was necessary to raise
+the concrete in a bucket with a derrick, and dump it into cars on the
+trestle above the top of the coping. Concrete was deposited through chutes,
+as in the lower face wall, continuously from the bottom of the face wall to
+the top of the retaining wall. At the commencement of each section of the
+retaining wall a layer of mortar was put on the rock. A 1:2:3 mixture of
+concrete was used in the face wall, and a 1:3:6 mixture in the retaining
+wall.
+
+As the face walls were so thin, the number of batches of concrete per hour
+was reduced, for the form filled so rapidly that the concrete, before it
+set, exerted an excessive pressure against the form, and this tended to
+make it bulge. The proper rate at which to place the concrete behind a form
+50 ft. long, with a wall 2 ft. thick, was found to be about fifteen 1/2-yd.
+batches per hour.
+
+_Cracks in Walls and Longitudinal Reinforcement._--Before the concrete
+walls were started, the contractor suggested using forms 100 ft. long and
+building the walls in sections of that length; it was decided, however, to
+limit the length to 50 ft.
+
+The south walls, in sections approximately 50 ft. long, were built first,
+starting at Tenth Avenue and extending for about 500 ft. Soon after the
+forms were removed, irregular cracks appeared in the walls between the
+joints in practically every section. It was thought that these cracks might
+be due to the wall being very thin and being held at the back by the
+tie-rods; there was also quite a material change in the section of the wall
+at each drainage box. Although it was admitted that these cracks would have
+no effect on the stability of the wall, it was thought that, for appearance
+sake, it would be desirable to prevent or control them, if possible. The
+first method suggested was to shorten the sections to 25 ft., which would
+give an expansion and contraction joint every 25 ft., it being thought that
+sections of this length would not crack between the joints. This, however,
+was not considered desirable. An effort was then made to prevent cracks in
+a section of wall, about 46 ft. long, on the south side, by using
+longitudinal reinforcement. In the lower and upper face walls, 3/4-in.
+square twisted steel rods were placed longitudinally about 4 in. in from
+the face and about 1 ft. 4 in. apart vertically. The sections of these
+walls were finished on April 10th, and May 5th, 1909, respectively. At
+present there are no indications of cracks in these sections, and they are
+practically the only ones in the south walls which do not show irregular
+cracks.
+
+It was decided, however, that, inasmuch as the cracks did not affect the
+stability of the walls, the increased cost of thus reinforcing the
+remaining walls was not warranted. An effort to control the cracks was made
+by placing corrugated-iron diaphragms in the form, dividing each 50-ft.
+section into three parts. The diaphragms were 1 ft. wide, and were placed
+with the outer edge 1 in. in from the face of the wall, but in the copings
+they were omitted. The purpose of these diaphragms was to provide weak
+sections in the walls, so that if there was any tendency to crack it would
+occur along the line of the diaphragms. Corrugated iron was used for the
+diaphragms instead of sheet iron as it was more easily maintained in a
+vertical position. The general arrangement of the diaphragms is shown on
+Fig. 4, Plate LII. The results obtained by using diaphragms have been quite
+satisfactory, and cracks approximately straight and vertical have usually
+appeared opposite the diaphragms soon after the forms were removed.
+Diaphragms were used on all the remaining walls, with the exception of
+those between Stations 187 + 07 and 188 + 83 on the north side, where the
+rock was of poor character and bad slides had occurred. Between these
+points, in order to strengthen the wall, twisted steel rods, 1 in. square,
+were placed longitudinally, 6 in. in from the face of the wall and 2 ft.
+apart vertically, between Elevations 295 and 335.
+
+[Illustration: PLATE LII, FIG. 1.--GIRDERS UNDER 9TH AVENUE ELEVATED
+RAILROAD.]
+
+[Illustration: PLATE LII, FIG. 2.--TW 100. P.T. & T.R.R. Co. Terminal
+Station West. Showing excavation of completion of South abutment 9th Ave.
+and method of Supporting Elevated Railway Column 488. July 21, 09.]
+
+[Illustration: PLATE LII, FIG. 3.--TW 31. P.T. & T.R.R. Co. Terminal
+Station West. View showing excavation 9th and 10th Avenues South of 32nd
+St. looking West from Sta. 184. Aug. 17, 07.]
+
+[Illustration: PLATE LII, FIG. 4.--TW 101. P.T. & T.R.R. Co. Terminal
+Station West. Inside of concrete form for lower-face wall, showing drains,
+tie rods, diaphragms and methods employed for tying in the form in addition
+to braces outside. July 21, 09.]
+
+_Tenth Avenue Portal._--The design of the Tenth Avenue Portal is shown on
+Fig. 9. The stone selected came from the Millstone Granite Company's
+Quarries, Millstone Point, Conn., and is a close-grained granite. Fig. 2,
+Plate LI, shows the completed portal.
+
+Practically all the stone cutting was done at the quarry, but certain
+stones in each course were sent long and were cut on the ground, in order
+to make proper closures. Drains were left behind the portal around the back
+of each arch, leading down to the bottom, and through the concrete base at
+each side of the portal and in the central core-wall; all these drains have
+been discharging water.
+
+_Power-House._--The old church at No. 236 West 34th Street, between Seventh
+and Eighth Avenues, was turned over to the New York Contracting
+Company-Pennsylvania Terminal for a power-house to supply compressed air
+for use on the Terminal Station work between Seventh and Ninth Avenues and
+the work below sub-grade as well as that on the Terminal Station-West. Four
+straight-line compressors and one cross-compound Corliss compressor were
+installed, the steam being supplied by three Stirling boilers. Three
+electrically-driven air compressors, using current at 6,600 volts, were
+also installed, and the total capacity of the power-house was about 19,000
+cu. ft. of free air per minute compressed to 90 lb. per sq. in.
+
+_Disposal Pier._--The disposal pier (old No. 62 and new No. 72), at the
+foot of West 32d Street, North River, was leased by the Pennsylvania
+Railroad Company. The entire pier, with the exception of the piles, was
+taken down, and the piles which would be in the path of the proposed tunnel
+were withdrawn prior to the building of the tunnels and the construction of
+the pier for disposal purposes. Subsequent to the driving of the tunnels
+there was a considerable settlement in the pier, especially noticeable at
+the telphers, and finally these had to be abandoned on this account. Fig.
+3, Plate LI, shows the chutes through which the earth was dumped on the
+decks of the scows to form a padding on which to dump the heavier rock.
+Fig. 4, Plate LI, shows the derricks at the end of the pier. These were
+used, not only for loading heavy stones and skips, but also with a
+clam-shell bucket for bringing in broken stone and sand for use in the
+work. Large quantities of pipe, conduits, brick, etc., were also brought to
+this pier for use on the work.
+
+[Illustration: FIG. 9. (Full page image)
+
+PORTAL, RETAINING AND FACE WALLS, TENTH AVENUE]
+
+
+ORGANIZATION OF ENGINEERING FORCE IN FIELD.
+
+The design and execution of the work were under the direction of Charles M.
+Jacobs, M. Am. Soc. C.E., Chief Engineer, and James Forgie, M. Am. Soc.
+C.E., Chief Assistant Engineer. The writer acted as Resident Engineer.
+
+[Illustration: Fig. 10.]
+
+The general organization of the engineering force in the field is shown by
+the diagram, Fig. 10.
+
+The position of Assistant Engineer, in responsible charge of Construction
+and Records, has been filled in turn by Messrs. A.W. Gill, N.C. McNeil,
+Jun. Am. Soc. C.E., and W.S. Greene, Assoc. M. Am. Soc. C.E.
+
+Messrs. A.P. Combes and T.B. Brogan have acted as Chief Inspector and Night
+Inspector, respectively, in charge of outside work during the entire
+carrying out of the contract.
+
+Base lines had been established on Ninth and Tenth Avenues for the Terminal
+work east of Ninth Avenue and for the Tunnel work west of Tenth Avenue,
+and these lines, together with bench-marks similarly established, were used
+in laying out the Terminal Station-West work.
+
+Prior to the commencement of the work, elevations were taken on the surface
+at 10-ft. intervals, and elevations of the rock surface were taken on these
+points as the rock was uncovered. Cross-sections were made and used in
+computing the progress and final estimates.
+
+Very careful records were kept of labor, materials, derrick performances,
+steam-shovel performances, quantity of dynamite used, etc., and, in
+addition, a diary was kept giving a description of the work and materials
+used each day; various tables and diagrams were also prepared.
+
+A daily report was sent to the Chief Office showing the quantities of
+excavation removed and concrete built, the force in the field, the plant at
+work, etc., during the previous day. At the end of each month a description
+of the work done during that month, with quantities, force of men employed,
+percentages of work done, etc., was sent to the Chief Office. Two diagrams,
+showing cross-sections and contours of the excavation done and the progress
+of the concrete walls, were also sent.
+
+
+COST ACCOUNT.
+
+From the records of labor and material obtained in the field, and from
+estimated charges for administration and power, an estimate was made of the
+cost to the contractor for doing various classes of work. It was necessary
+to estimate the administration and power charges, as the contractor's
+organization and power-house were also controlling and supplying power to
+the Terminal Station work east of Ninth Avenue and also the work below
+sub-grade. The labor and material charges in the field were placed directly
+against the class of work on which they were used and the administration
+and general charges (which included superintendence, lighting, etc.) were
+apportioned to the various classes of work in proportion to the value of
+the labor done.
+
+
+STATISTICS.
+
+The total weight of the structural steel used during the underpinning of
+Ninth Avenue was 1,475,000 lb.
+
+The total weight supported during the work under Ninth Avenue was about
+5,000 tons.
+
+\U$1\EThe average daily traffic over the Ninth Avenue Elevated Railway was
+90,000 passengers, and, during the progress of the excavation and
+underpinning, about 100,000,000 passengers were carried over that
+structure.
+
+The total excavation was 521,000 cu. yd., of which 87% was solid rock.
+
+The average drill performance was about 33 lin. ft. per 8-hour shift.
+
+The average number of cubic yards of excavation per drill shift was 13.9.
+
+The average number of feet of drilling per cubic yard of excavation was
+about 2.4.
+
+The average excavation per pound of dynamite was 2.2 cu. yd.
+
+The average amount of excavation per derrick shift of ten hours, 87% of the
+excavation being rock, was 50 cu. yd.
+
+The average derrick force per shift, including only foreman and laborers,
+was 13 men.
+
+The salaries of the engineering staff in the field and the expenses of
+equipping and maintaining the field office amounted to 2.8% of the cost of
+the work executed, 2.7% being for engineering salaries alone.
+
+FOOTNOTES:
+
+[Footnote A: Presented at the meeting of April 6th, 1910.]
+
+
+
+
+
+End of the Project Gutenberg EBook of Transactions of the American Society
+of Civil Engineers, vol. LXVIII, Sept. 1910, by B.F.  Cresson, Jr
+
+*** END OF THIS PROJECT GUTENBERG EBOOK SOCIETY OF CIVIL ENGINEERS ***
+
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