,,american ,,society ,,of ,,civil ,,engineers ,,instituted #aheb ,,transactions ,paper ,no4 #aaef ,,the ,,new ,,york ,,tunnel ,,extension ,,of ,,the ,,pennsylvania ,,railroad4 ,,the ,,terminal ,,station-,,west4,a ,,by ,b4,f4 ,,cresson1 ,,jr41 ,m4 ,,am4 ,,soc4 ,c4,e4 ,location of ,work4--,the area covered by the work of the ,terminal ,station-,west is bounded as follows3 ,by the east line of ,ninth ,avenue2 by the south side of #cast ,street to a point about #bjj ft4 west of ,ninth ,avenue2 by a line running parallel to ,ninth ,avenue and about #bjj ft4 therefrom1 from the south side of #cast ,street to the boundary line between the #cast and #cb;d ,street properties2 by this line to the east line of ,tenth ,avenue2 by the east line of ,tenth ,avenue to the boundary line between the #cb;d and #cc;d ,street properties2 by this line to the east line of ,ninth ,avenue4 ,the area is approximately #f4c acres4 ,house-,wrecking4--,the property between ,ninth and ,tenth ,avenues was covered with buildings1 #id in number1 used as dwelling and apartment houses and church properties1 and it was necessary to remove these before starting the construction4 ,most of the property was bought outright by the ,railroad ,company1 but in some cases condemnation proceedings had to be instituted in order to acquire possession4 ,in the case of the property of the ,church of ,st4 ,michael1 fronting on ,ninth ,avenue1 #cast and #cb;d ,streets1 the ,railroad ,company agreed to purchase a plot of land on the south side of #cdth ,street1 west of ,ninth ,avenue1 and to erect thereon a church1 rectory1 convent1 and school1 to the satisfaction of the ,church of ,st4 ,michael1 to hand over these buildings in a completed condition1 and to pay the cost of moving from the old to the new buildings1 before the old properties would be turned over to the ,railroad ,company4 ,the house-wrecking was done by well-known companies under contract with the ,railroad ,company4 ,these companies took down the buildings and removed all the materials as far as to the level of the adjacent sidewalks4 ,the building materials became the property of the contractors1 who usually paid the ,railroad ,company for the privilege of doing the house-wrecking4 ,the work was done between ,april and ,august1 #aijf1 but the buildings of the ,church of ,st4 ,michael were torn down between ,june and ,august1 #aijg4 ,the bricks were cleaned and sold directly from the site1 as were practically all the fixtures in the buildings4 ,the stone fronts were broken up and left on the premises4 ,some of the beams were sold on the premises1 but most of them were sent to the storage yards4 ,some of the lath and smaller timber was sold for firewood1 but most of it was given away or burned on the premises4 ,contracts and ,agreements4--,the main contract1 awarded to the ,new ,york ,contracting ,company-,pennsylvania ,terminal on ,april #bhth1 #aijf1 included about #ejb1jjj cu4 yd4 of excavation 7about #ij being rock71 #ag1hbj cu4 yd4 of concrete walls1 #a1cbj1jjj lb4 of structural steel1 #fch1jjj ft41 ,b4,m41 of framed timber1 etc41 etc4 ,this contract was divided into two parts3 ,work ,in and ,under ,ninth ,avenue and ,work ,between ,ninth and ,tenth ,avenues1 and unit prices were quoted for the various classes of work in each of these divisions4 ,the prices quoted for excavation included placing the material on scows supplied by the ,railroad ,company at the pier at the foot of ,west #cb;d ,street1 on the ,north ,river2 there was a clause in the contract1 however1 by which the contractor could be required to make complete disposal of all excavated material at an additional unit price1 and this clause was enforced on ,january #ast1 #aiji1 when about #id of the excavation had been done4 ,for the purpose of disposing of the excavated material in the easterly portion of the ,terminal1 the ,new ,york ,contracting ,company-,pennsylvania ,terminal had excavated under ,ninth ,avenue a cut which came to the grade of #cb;d ,street about midway between ,ninth and ,tenth ,avenues1 and a trestle was constructed from this point over ,tenth ,avenue and thence to the disposal pier at the foot of ,west #cb;d ,street4 ,on ,may #aath1 #aijf1 the work of excavation was commenced on the east side of ,ninth ,avenue1 and on ,july #ith1 #aijf1 on the south side of #cast ,street1 between ,ninth and ,tenth ,avenues4 ,from the beginning1 the excavation was carried on by day and night shifts1 except on ,sundays and holidays1 until ,january1 #aiji1 except that during the period from ,november1 #aijg1 to ,october1 #aijh1 the night shift was discontinued4 ,geology4--,the rock encountered may be classed as gneiss2 its character varied from granite to mica schist4 ,it was made up of quartz1 feldspar1 and mica1 and there were also some isolated specimens of pyrites1 hornblend1 tourmaline1 and serpentine4 ,on the south side of the work1 just west of ,ninth ,avenue1 there were excellent examples of contortions of veins of quartz in the darker rock4 ,on the east side of ,ninth ,avenue1 near the north end of the work1 glacial marks were found on the rock surface4 ,the general direction of the stratification was north #e west1 and the general incline about #fj with the horizontal4 ,as a rule1 the rock broke sharply along the line of stratification4 ,on the south side it broke better than on the north side1 where it was usually softer and more likely to slide2 and this1 together with the fact that in winter it was subject to alternate freezing and thawing and in summer to the direct rays of the sun1 made it rather difficult to get a good foundation for the retaining walls4 ,,work ,,in ,,and ,,under ,,ninth ,,avenue4 ,general ,description4--,the work involved the excavation of about #cge ft4 of the full width of ,ninth ,avenue to an average depth of about #eh ft41 and the construction over this area of a steel viaduct1 the deck of which was about #bd ft4 below the surface1 for the ultimate support of the ,ninth ,avenue structures4 ,the following estimated quantities appear in the contract3 ,excavation of rock1 #gb1fjj cu4 yd42 excavation of all materials except rock1 #i1cjj cu4 yd42 concrete 7#a3c3f7 in abutments1 etc41 #a1fhj cu4 yd42 timber1 #ejd1jjj ft41 ,b4,m42 structural steel1 #a1cbj1jjj lb41 etc4 ,while this excavation was being done it was necessary to support and maintain the three-track elevated railway structure of the ,interborough ,rapid ,transit ,company1 of which #ah columns1 or a length of about #cdj ft41 were affected1 the two-track surface railway structure of the ,new ,york ,city ,railway ,company1 and various pipes1 sewers1 and conduits1 and to maintain all surface vehicular and pedestrian traffic4 ,all structures were left in place with the exception of the pipes1 most of which were temporarily cut out4 ,the #dh-;in4 brick sewer in the center of ,ninth ,avenue was broken1 and the sewage was pumped across the excavation through a smaller pipe4 ,the general method adopted was as follows3 ,the east and west sides of the avenue were closed1 vehicular traffic was turned into the center1 and a trestle for pedestrians was constructed west of the westerly elevated railway columns4 ,all structures were then supported on transverse girders1 running across the avenue1 below the surface1 and these rested on concrete piers on the central rock core4 ,the sides of the avenue were then excavated to sub-grade1 and the permanent steel viaduct was erected on both sides of the avenue as close as possible to the central rock core4 ,the weight of all structures was then transferred to the permanent steel viaduct1 erected on the sides of the avenue1 by timber bents under the transverse girders resting on the permanent steel viaduct1 and all weight was thus taken off the central rock core4 ,this core was then excavated to sub-grade1 the permanent viaduct was completed1 and all structures were placed on its deck1 using concrete piers and timber bents4 ,the design and erection of the permanent steel viaduct and the permanent foundations on its deck were done under another contract1 apart from the ,north ,river ,division work1 and are not described in this paper4 ,elevated ,railway ,structure of the ,interborough ,rapid ,transit ,company4--,the ,ninth ,avenue ,elevated ,railway was built between #ahgg and #ahhj as a two-track structure1 the design being such as to permit a third or central track to be added later1 and this was built in #ahid4 ,it is supported on columns under the outside tracks1 about #dc ft4 from center to center longitudinally and #bb ft4 #c in4 from center to center transversely1 the central track being carried by transverse girders between the columns4 ,the columns carrying the structure are of fan top design1 with the points of bearing near the extremities at the top2 each of the outside tracks is supported on two longitudinal latticed girders and the central track on two plate girders2 between the columns1 transverse girders are spliced to the outside track cross-frames1 and carry the central track system4 ,it was not thought desirable to put brackets on the columns near the street level to support the structure temporarily1 and1 as there is an expansion joint at each column1 and as the transverse girders carrying the central track system are not rigidly attached to the longitudinal girders carrying the outside tracks1 the central track could not be supported by supporting the outside tracks2 therefore1 independent supports for each track1 in the form of overhead girders1 had to be provided4 ,the columns rest on brick piers1 each having four #b-;in4 anchor-bolts4 ,the brick foundations on the west side are wide in order to allow a #bd-;in4 water main to pass directly beneath the columns4 ,the foundations are usually on rock4 ,illustration3 ,,plate ,,xlvii1 ,,fig4 #a4--,,tw #d1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,view of #ith ,ave4 looking ,northwest from #cbnd ,street1 prior to commencement of work4 ,april #bc1 #jf4 ,illustration3 ,,plate ,,xlvii1 ,,fig4 #b4--,,tw #ag1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,view of ,east side of #ith ,ave4 looking ,north from a point #ajj feet south of #ccrd ,st4 showing condition of work4 ,july #bc1 #jf4 ,illustration3 ,,plate ,,xlvii1 ,,fig4 #c4--,,tw #be1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,view showing permanent and temporary supports of #ith ,ave4 ,structures1 looking ,northwest from #cast4 ,st4 ,april #bd1 #jg4 ,illustration3 ,,plate ,,xlvii1 ,,fig4 #d4--,,tw #bh1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,east side of #ith ,avenue1 ,north of #cbnd ,st4 looking ,west1 showing rock excavation and supports of #ith ,avenue structures4 ,aug4 #ag1 #jg4 ,fig4 #a1 ,plate ,,xlvii1 shows the elevated railway structure and the street surface prior to the commencement of the work4 ,the east track is used for north-bound local trains1 the west track for south-bound local trains1 and the central track for south-bound express trains between #g and #i4cj ,a4,m4 and for north-bound express trains between #b4cj and #g ,p4,m4 ,it is said that an average of #ij1jjj passengers are carried over this structure every #bd hours4 ,surface ,railway ,structure of the ,new ,york ,city ,railway ,company4--,this is an electric surface railway of the ordinary type1 the rail and slot being bedded in concrete1 with cast-iron yokes every #e ft4 ,there are manholes every #ajj ft41 and cleaning-out holes every #ae ft4 ,power conduits are bedded in the concrete on the east side of the east track4 ,forty-eight-,inch ,brick ,sewer4--,this sewer was in the center of ,ninth ,avenue1 with the invert about #ab ft4 below the surface1 and manholes about #ajj ft4 apart1 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 done4 ,twenty-four-,inch ,cast-,iron ,water ,main4--,this water main was laid under the west elevated railway columns1 with its top about #c ft4 below the surface1 a space being left for it in the brick foundations1 and a large column base casting being used to span it4 ,valves were installed1 one north of #cc;d ,street and one south of #cast ,street1 prior to excavating near the pipe1 so that if it was broken the water could be shut off promptly4 ,street ,surface4--,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 side1 but1 at the contractor's request1 both sides were closed1 and all vehicular traffic was turned into the center4 ,a light trestle on the west side of the avenue provided for pedestrian traffic4 ,other ,sub-surface ,structures4--,there were various gas mains1 water mains1 electric conduits1 manholes1 hydrants1 etc41 in the avenue1 and most of these were cut out temporarily1 at the contractor's request1 to be replaced subsequently4 ,supports for ,elevated ,railway ,structure4--,as stated previously1 the central track had to be supported independently4 ,the overhead girders1 known as girders ,b1 were therefore designed as shown on ,fig4 #a1 and put in place as shown on ,figs4 #b and #c4 ,the outside tracks were blocked directly on these girders1 and the central track was supported by blocking up the transverse girders on ,i-beams placed between the girders ,b2 and no blocking was placed between the girders ,b and the longitudinal girders carrying the central track4 ,the weight on each column was assumed to be #agb1jjj lb4 ,illustration3 ,,fig4 #a4 7,full page image7 ,,details ,,of ,,steel ,,girders1 ,,etc4 ,,supporting ,,ninth ,,avenue ,,structures ,supports for ,surface ,railway ,structure4--,a uniform load of #c1jjj lb4 per lin4 ft4 of single track1 with the weight of a car at #ci1jjj lb41 was assumed4 ,several feet of earth1 between the structure and the rock1 were mined out1 and the structure was supported on ,i-beams and posts1 and ultimately on the transverse girders by using timber bents under the ,i-beams1 as shown on ,fig4 #c4 ,water ,mains and ,sewer4--,cradles were designed for the support of the #dh-;in4 and #bd-;in4 water mains1 resting on the transverse girders1 and the #dh-;in4 cast-iron sewer on the east side of the avenue was carried on ,i-beams bracketed to the ends of the transverse girders1 as shown on ,figs4 #a and #b4 ,illustration3 ,,fig4 #b4 7,full page image7 ,,method ,,of ,,supporting ,,elevated ,,railway ,,structure ,illustration3 ,,fig4 #c4 7,full page image7 ,,method ,,of ,,supporting ,,tracks ,,of ,,new ,,york ,,city ,,railway ,,co4 ,girders ,c4--,the transverse girders below the street surface1 referred to above1 were known as girders ,c1 and they were put in place at first resting on concrete piers on the central core2 the weight of all structures was placed on them while the sides of the avenue were being excavated1 and the sides of the viaduct were being built4 ,the ends of these girders were then picked up on the sides of the viaduct1 and1 spanning the central rock core1 carried all structures while the core was being excavated and the viaduct completed4 ,new foundations were then placed on the deck of the viaduct to carry all structures4 ,fifty-four of these girders were required1 each weighing about #ai1jjj lb4 ,the bents carrying the ends of these girders on the sides of the viaduct are shown on ,fig4 #b4 ,they were of long-leaf yellow pine4 ,these girders were located so that a cradle could be laid on them east of the elevated railway structure to carry a proposed #dh-;in4 cast-iron water main4 ,girders ,b4--,eighteen of these girders were required1 each weighing about #f1jjj lb4 ,the timber bents supporting these girders1 shown on ,fig4 #b1 were of long-leaf yellow pine4 ,the total weight1 including the elevated railway structure1 surface railway structure1 pipes1 etc41 supported during the work1 amounted to about #e1jjj tons4 ,details of the ,work4--,the method in general is shown on ,figs4 #d and #e4 ,at first the east side of the avenue was closed and excavated down to rock1 the earth was mined out under alternate yokes of the surface railway structure1 and temporary posts were placed under the yokes to support the structure while the remainder of the earth was being removed4 ,then needle-beams and posts were placed under each yoke4 ,the concrete forming the track structure was then enclosed with planking to prevent it from cracking and falling4 ,i-beams were then placed under the needle-beams carrying the structures1 and these were carried on posts2 they were changed alternately until the excavation had been taken out to a depth of about #af ft4 below the surface4 ,in placing these ,i-beams1 heavier blocking was used in the center of the span than at the ends where the bents would come1 to prevent the subsidence of the track owing to the sag in the ,i-beams4 ,as much excavation1 to a depth of about #bj ft41 was taken out adjoining the elevated railway foundations as could be done with safety4 ,fig4 #b1 ,plate ,,xlvii1 shows this condition of the work4 ,the #dh-;in4 brick sewer was broken1 and the sewage was pumped across the excavation4 ,the overhead girders ,b were then put in place1 and two of the girders ,c were used as temporary shoring girders at each column4 ,these1 as shown by ,fig4 #c1 ,plate ,,xlvii1 were placed parallel to the elevated railway1 with blocking between them and the girders ,b4 ,double bents1 independent of each other1 were placed under the ends of these temporary shoring girders1 and these were braced securely to prevent possible dislodgment during the removal of the rock4 ,the weight of the structure was then taken by jacking up the girders near the bents until the column was lifted off the old foundation2 blocking was put in between the girders and the bents during the jacking1 so that when the jacks were released the base of the column was still clear of the old foundation4 ,one #hj-ton jack was used for this purpose1 and the general method is shown by ,fig4 #a1 ,plate ,,lii4 ,illustration3 ,,fig4 #d4 7,full page image7 ,,method ,,of ,,excavating ,,ninth ,,avenue ,,plan ,,and ,,elevation ,,showing ,,various ,,stages ,,of ,,the ,,work ,illustration3 ,,fig4 #e4 7,full page image7 ,,method ,,of ,,excavating ,,ninth ,,avenue ,,sections ,,showing ,,various ,,stages ,,of ,,work ,no4 #a ,condition ,prior to ,commencement of ,work ,no4 #b ,east side of ,avenue cut down about #bj ft4 ,beams with ,supporting ,posts placed under ,surface ,railway ,tracks4 ,girders ,b and ,temporary ,shoring ,girders ,c for supporting ,elevated ,ry4 in place4 ,no4 #c ,i's in place under ,surface ,ry4 ,tracks4 ,elevated ,ry4 carried on ,temporary ,shoring ,girders1 and ,girders ,c in place4 #bd ,water ,main carried on ,timber ,cradle and sewage carried through ,pipe ,r4 ,foot ,walk carried on ,girders ,c in place on ,west ,side of ,avenue4 ,no4 #d ,elevated ,railway carried on ,bents under ,columns4 ,temporary ,shoring ,girders removed and ,permanent ,bents resting on ,girders ,c in place4 ,bents in place on ,girders ,c carrying ,surface ,railway4 ,east and ,west sides of ,avenue excavated down to ,sub-,grade and ,five rows of ,permanent ,steel in place on each side4 ,bents erected on ,permanent ,steel to catch ends of ,girders ,c while #b outside ,concrete ,piers are removed and #fth row of ,permanent ,steel on each side is put in place4 ,no4 #e ,two outside ,concrete ,piers removed and #fth row of ,permanent ,steel in place4 ,girders ,c carrying all structures now resting on ,bents on ,permanent ,steel4 #dh ,c4l4 ,sewer carried on ,brackets on ,girders ,c4 ,no4 #f ,excavation ,completed4 ,temporary raker braces were placed against the structure to prevent lateral movement4 ,four sets of these temporary shoring girders were used in this manner1 two sets starting at the north end and two sets at about the middle of the work1 and these sets were moved south as they were released4 ,the columns being thus supported on temporary shoring girders1 the old foundations were removed and the excavation was taken down to a level about #af ft4 below the surface4 ,two sets of three of the girders ,c were then put in place under the avenue at each column1 each set being placed on four concrete piers #f ft4 square with spaces of #d ft4 between them1 so that the outside of the outside pier would be #ah ft4 from the center of the avenue and #cb ft4 from the house line4 ,this is shown on ,fig4 #e and on ,fig4 #c1 ,plate ,,xlvii4 ,four small piers were used1 as they could be more easily removed than one continuous pier4 ,the girders ,c were set to line and grade1 and the piers were built under them1 great care being taken to get the concrete well under the girders so as to give a firm bearing4 ,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 ,b1 being in the same plane2 and provision had to be made to support the structure while this was being done4 ,therefore1 double bents were erected directly beneath the columns1 as shown by ,figs4 #b1 #d1 and #e1 and by ,fig4 #c1 ,plate ,,xlvii4 ,these were built with their sills resting on the girders ,c1 and blocking was put in between the sills and the rock to carry the full weight of the structure4 ,later1 when the weight of the structure was carried on the permanent bents1 this blocking was knocked out1 but the bents were left in to carry the weight of the column itself1 which was swinging more or less from the structure above4 ,the weight of the structure was placed on these bents directly beneath the columns by jacking up the temporary girders again1 putting blocking between the bents and the base of the columns1 and taking out the blocking which had been put in previously under the temporary shoring girders4 ,the #bd-;in4 water main was carried over the excavation on cables from the temporary shoring girders1 except when they were being jacked up1 at which time posts were placed beneath it4 ,anchor-bolts were put in place between the column bases and the bents directly beneath1 in order to increase the lateral stiffness1 and raker braces were also used4 ,this having been done1 the temporary shoring girders were moved south to the next column1 where the process was repeated4 ,the timber bents1 shown in detail by ,fig4 #b1 were then put in place as shown by ,figs4 #d and #e1 and by ,fig4 #c1 ,plate ,,xlvii4 ,these bents were framed as tightly as possible1 using generally a #bj-ton jack1 and they were erected simultaneously at each pair of columns4 ,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 column4 ,on releasing the jack the weight was transferred to the permanent timber bents1 and the east and west columns of each pair were transferred on the same day4 ,one #hj-ton jack was used on the easterly columns and two were necessary on the westerly columns1 one on each side of the #bd-;in4 water main4 ,the raker braces of these permanent bents were not framed as tightly as the main posts1 in order that the main post should carry the entire weight and the raker braces merely steady the structure4 ,timber bents were erected on girders ,c to carry the ,i-beams under the surface railway structure1 as shown on ,fig4 #c1 and all temporary posts under these ,i-beams were removed4 ,the bents were framed with a jack1 as tightly as possible1 and very little settlement of the track occurred4 ,a cradle was then built under the #bd-;in4 water main and placed on girders ,c1 and1 as a temporary footwalk had been constructed on the west side of the avenue1 it will be seen that all structures were thus carried on girders ,c4 ,all structures were put on the girders ,c before continuing the excavation on the sides of the avenue because1 in case of a slide of rock1 there would be less danger than to individual structures4 ,the outside piers1 on which the girders ,c rested1 might even be lost1 without affecting the stability of the structure1 and posting could readily be done beneath these girders in case of necessity4 ,a very careful record of levels1 taken on the elevated railway columns1 was kept1 observations being made during each jacking up and at least twice a week during the progress of the work4 ,the columns were usually kept about #a_/b in4 high so as to allow for compression in the timber bents4 ,as a rule1 no jacking of the elevated railway structure was done while trains were passing over1 and trains were flagged during the operation4 ,there was generally very little delay1 as all jacking was done between #aj4cj ,a4,m4 and #b4cj ,p4,m41 when the traffic was lightest1 and frequently the jacking was done between trains1 causing no delay whatever4 ,steel clamps were placed1 three on the top and three on the bottom of each set of the girders ,c1 to bind them together and cause them to act as a unit4 ,all structures then being supported on girders ,c1 which were carried on four concrete piers resting on the central rock core1 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 constructed4 ,the central rock core was about #cf ft4 wide on the top and #de ft4 wide on the bottom1 and at the center of #cb;d ,street it was about #db ft4 high4 ,it was the original intention to excavate a sufficient width of the sides of the avenue to erect six rows of the permanent steel viaduct1 #e ft4 from center to center1 and this was done on the south portion of the work4 ,on the north portion1 however1 the rock was of poor quality1 and it was thought best to excavate for only five rows at first1 to erect the five rows of permanent steel and put the timber bents in place under the ends of the girders ,c1 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 row4 ,additional raker braces were put in these bents temporarily1 and were removed when the sixth row of steel had been erected4 ,this is shown on ,figs4 #d and #e4 ,illustration3 ,,plate ,,xlviii1 ,,fig4 #a4--,,tw #cc1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,east side of #ith ,ave4 looking ,north from #cast ,st41 showing rock excavation and supports of #ith ,ave4 structures4 ,dec4 #bh1 #jg4 ,illustration3 ,,plate ,,xlviii1 ,,fig4 #b4--,,tw #ci1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,east side of #ith ,ave4 looking ,north from #cast ,street1 showing rock excavation and permanent steel work4 ,march #bd1 #jh4 ,illustration3 ,,plate ,,xlviii1 ,,fig4 #c4--,,tw #gc1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,west side of ,ninth ,ave4 ,jacking up girders ,c at ,elevated ,railroad ,column #dia1 showing method of taking weight on permanent viaduct girders4 ,nov4 #ad1 #jh4 ,illustration3 ,,plate ,,xlviii1 ,,fig4 #d4--,,tw #eh1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,east side of ,ninth ,ave4 looking ,north from #cast ,st41 showing underpinning of ,ninth ,ave4 ,structures4 ,aug4 #aj1 #jh4 ,fig4 #d1 ,plate ,,xlvii1 and ,fig4 #a1 ,plate ,,xlviii1 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 girders4 ,fig4 #a1 ,plate ,,xlviii1 shows also the easterly portion of the concrete north abutment4 ,fig4 #b1 ,plate ,,xlviii1 shows five rows of the permanent viaduct girders erected on the east side of the work4 ,the excavation of the sides of the avenue having been completed1 and six rows of permanent viaduct girders erected on both sides1 timber bents1 as shown on ,figs4 #b1 #d1 #e1 and #f1 were erected on this steel to support the ends of the girders ,c and carry the structure while the rock core was being excavated4 ,fig4 #c1 ,plate ,,xlviii1 shows the method of taking the weight on these bents4 ,four #hj-ton jacks were used1 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 bents2 all four of these jacks were operated simultaneously1 and the girders ,c were lifted off the bents and clear of the concrete piers4 ,oak filling pieces were then inserted between the bents and the girders ,c1 so that when the jacks were released the girders ,c were clear of the concrete piers4 ,fig4 #c1 ,plate ,,xlviii1 shows that the girders have been lifted off the piers4 ,elevations were taken on each set of girders during each operation1 and careful observations were made on the elevated railway columns4 ,where the rock was very close to these bents1 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 materials4 ,fig4 #c1 ,plate ,,xlviii1 shows one of these bents filled with blocking4 ,all structures being carried on girders ,c1 which1 in turn1 were carried on the sides of the permanent viaduct1 the central core was excavated4 ,fig4 #d1 ,plate ,,xlviii1 and ,figs4 #a1 #b1 #c1 and #d1 ,plate ,,xlix1 show various views of the work at this stage4 ,the central portion of the viaduct was then erected1 and1 using concrete piers and timber bents1 all structures were placed on its deck4 ,fig4 #c1 ,plate ,,xlix1 shows the piers under the elevated railway columns prior to the removal of girders ,c4 ,illustration3 ,,fig4 #f4 7,full page image7 ,,general ,,arrangement ,,of ,,temporary ,,and ,,permanent ,,structures ,during the latter part of #aijh a #dh-;in4 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 avenue4 ,this is part of the high-pressure system1 and the location and elevation of this water main were taken into consideration when the underpinning was designed4 ,this main1 and the #dh-;in4 cast-iron sewer bracketed to girders ,c1 are shown on ,fig4 #d1 ,plate ,,xlviii4 ,elevations had been taken on marks on the elevated railway columns between #cjth and #cdth ,streets at the time the original surveys were made1 in #aijb1 and these marks were used to test the level of the structure during the progress of the excavation4 ,at the extreme south end of the work the procedure was changed4 ,the east side was excavated down to sub-grade1 the east portion of the south abutment was constructed1 and six rows of the permanent steel viaduct were erected4 ,very little excavation had been done on the west side of the avenue at the south end of the work1 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 steel2 therefore1 instead of supporting the girders ,c on the central rock core1 the east ends were taken up on the permanent viaduct girders1 and the west ends were supported on a concrete pier on the rock4 ,the central portion of the avenue was excavated in advance of the west portion4 ,the permanent viaduct girders were put in place from east to west across the avenue1 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 excavated1 the central portion of the south abutment having been constructed before the west portion4 ,this procedure was adopted only at the north girders ,c at elevated railway column ,no4 #dhh1 the south set of girders ,c being on the rock immediately south of the south abutment4 ,figs4 #b and #d1 ,plate ,,xlix1 and ,fig4 #b1 ,plate ,,lii1 show various stages of the work at the south end4 ,illustration3 ,,plate ,,xlix1 ,,fig4 #a4--,,tw #fj1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,under ,ninth ,ave41 looking ,south from ,north abutment1 showing underpinning and excavation of rock core4 ,aug4 #ac1 #jh4 ,illustration3 ,,plate ,,xlix1 ,,fig4 #b4--,,tw #hd1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,view looking toward ,ninth ,ave4 from ,south side of #cast ,st41 #bjj feet ,west of ,ninth ,ave4 ,jan4 #bh1 #ji4 ,illustration3 ,,plate ,,xlix1 ,,fig4 #c4--,,tw #hh1 ,p4,t4 ,t4,r4,r4 ,co4 ,n4,r4 ,div4 ,terminal ,station ,west4 ,center line of #cbnd ,st41 looking ,east from ,sta4 #ahcej1 showing excavation under ,ninth ,avenue1 permanent concrete piers under ,elevated ,railway ,columns and removal of temporary shoring girders ,c4 ,april #h1 #ji4 ,illustration3 ,,plate ,,xlix1 ,,fig4 #d4--,,tw #ie1 ,p4,t4 ,t4,r4,r4 ,co4 ,n4,r4 ,div4 ,terminal ,station ,west4 ,view under ,ninth ,avenue looking ,southward from #ajj feet ,south of center line1 showing underpinning of ,ninth ,avenue structure taken at sub-grade4 ,may #be1 #ji4 ,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 jacks1 and putting in filler pieces before releasing the jacks1 not trusting to wedging to transfer the loads4 ,in fact1 apart from the boxing-in of the surface railway concrete1 no wedges whatever were used4 ,this appears to have been a decided advantage1 for1 with the constant pounding of trains on the elevated railway and the jarring due to heavy trucks on the pavement blocks1 it is very likely that wedging would have become loosened and displaced1 whereas1 with blocking1 there was little or no tendency toward displacement due to vibration4 ,although the vibration of the structure1 when a long length was supported on girders ,c resting on the permanent viaduct girders on the sides of the avenue1 appeared to be considerable1 not only vertically but transversely1 very careful observation showed that the sag in the girder ,c due a live load of three elevated railway trains1 one surface railway car1 and one heavy truck1 amounted to #a_/h in4 ,the sideway vibration did not amount to more than #a_/cb in4 on either side of the normal position4 ,more vibration was caused by heavy trucks and wagons going over the stone pavement than by the elevated railway trains or surface cars4 ,no blasting was done near the supports of the elevated railway structure while trains were passing over it1 and occasionally trains were stopped during a heavy or uncertain blast4 ,a watchman on the surface1 day and night1 and at first one and later two flagmen on the elevated railway structure1 were on duty at all times1 reporting to the ,interborough ,rapid ,transit ,company1 by whom they were employed4 ,log mats and timber protection for the girders and the columns of the permanent viaduct were used1 as shown by ,figs4 #a and #d1 ,plate ,,xlix1 during the excavation of the rock core1 and timber was also used to protect the face of the completed portions of the concrete abutments4 ,in excavating the sides of the avenue1 the rock broke better on the east than on the west side1 where large seams developed and some slides occurred4 ,abutments4--,as shown on ,fig4 #g1 the face of the north abutment has a batter of #b in4 to the foot1 and the face of the south abutment has a variable batter1 the base being on a grade and the bridge seat being level1 and both maintaining a uniform distance from the center of the ,terminal ,yard4 ,the back walls of the abutments were not built until the steel had been put in place4 ,no attempt was made to water-proof these abutments1 but1 in the rear of the wall1 open spaces were left1 about #f ft4 from center to center1 which were connected with drain pipes at the base of and extending through the wall1 for the purpose of carrying off any water that might develop in the rock4 ,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 wall4 ,a hose was used to run water through these drains during the placing of the concrete1 for the purpose of washing out any grout which might run into them4 ,each box was washed out at frequent intervals1 and there was no clogging of the drains whatever4 ,this method of keeping the drains open was adopted and used successfully for the entire work4 ,the abutments were built of concrete1 and the mixture was #a part of cement1 #c parts of sand1 and #f parts of broken stone4 ,the concrete was mixed in a ,no4 #c ,ransome mixer1 and was placed very wet4 ,no facing mixture or facing diaphragms were used1 but the stone was spaded away from the face of the wall as the concrete was laid4 ,chutes were used inside the form1 if the concrete had to drop some distance4 ,work was continued day and night1 without any intermission1 from the time of commencement to the time of completion of each section4 ,the face of the concrete wall was rubbed and finished in a manner similar to that used on the walls between ,ninth and ,tenth ,avenues1 as described later4 ,fig4 #b1 ,plate ,,lii1 shows the east and central portions of the south abutment1 completed and carrying the permanent viaduct1 and the excavation completed for the west portion4 ,,work ,,between ,,ninth ,,and ,,tenth ,,avenues4 ,general ,description4--,the work involved the excavation of about #e4d acres1 between the west house line of ,ninth ,avenue and the east house line of ,tenth ,avenue1 to an average depth of about #ej ft41 the construction of a stone masonry portal at ,tenth ,avenue leading to the ,river ,tunnels1 and the construction around the site of the concrete retaining and face walls4 ,the following estimated quantities appear in the contract3 ,excavation of rock in trenches1 #c1djj cu4 yd42 excavation of rock in pit1 #cgg1jjj cu4 yd42 excavation of all materials except rock in trenches1 #f1ejj cu4 yd42 excavation of all materials except rock in pit1 #cd1jjj cu4 yd42 concrete1 #a3c3f1 in retaining walls1 #d1ehj cu4 yd42 concrete1 #a3c3f1 in face walls1 #g1dfj cu4 yd42 concrete1 #a3b3c1 with #c_/d-;in4 stone1 in face walls1 #d1ajj cu4 yd42 stone masonry in portal1 #bdg cu4 yd41 etc41 etc4 ,illustration3 ,fig4 #g4 7,full page image7 ,,ninth ,,ave4 ,,abutments ,,key ,,plan ,as previously stated1 the contract price included the placing of all excavated material on scows at ,pier #fb1 ,north ,river4 ,prior to this contract this pier had been used by the ,new ,york ,contracting ,company-,pennsylvania ,terminal1 for the disposal of excavated material from east of ,ninth ,avenue4 ,in order to get the material to the pier1 the contractor had excavated a cut under ,ninth ,avenue which came to the grade of #cb;d ,street about midway between ,ninth and ,tenth ,avenues1 and a trestle was constructed from this point over ,tenth ,avenue and thence to the pier4 ,fig4 #b1 ,plate ,,xlvii1 shows the east end of this cut1 and ,fig4 #a1 ,plate ,l1 shows the trestle1 looking east from ,tenth ,avenue4 ,a #cj-ton steam shovel was brought to the south side of the work1 and commenced operating on ,july #ith1 #aijf4 ,after working there about a month1 the earth had been practically stripped off the rock1 and the shovel was moved over to the north side where it excavated both earth and rock until ,august #ajth1 #aijg4 ,at three points south of #cb;d ,street and at one point north of #cb;d ,street near ,tenth ,avenue1 cuts were made in the rock to sub-grade1 and from these cuts1 together with the cuts on the west side of ,ninth ,avenue1 all widening out was done and the excavation was completed4 ,fig4 #a1 ,plate ,l1 shows the excavation of the three cuts on the south side of #cb;d ,street1 the steam shovel operating on the north side of that street1 and the material-disposal tracks and trestle4 ,fig4 #c1 ,plate ,,lii1 shows the cuts joined up and the excavation along the south side practically completed4 ,on the north side of the work1 between ,stations #ahb #ij and #ahc #fe1 the rock was low1 and provision had to be made for maintaining the yards to the north of the site4 ,therefore a rubble-masonry retaining wall was built1 with the face about #b ft4 north of the face of the proposed concrete wall which was to be put in later4 ,on the same side of the work1 between ,stations #ahh #bd and #ahh #df1 the rock was exceedingly poor1 and as a small frame house on the adjoining lot was considered to be in an unsafe condition1 a rubble masonry retaining wall was built4 ,as the building adjoining the south side of the work at ,tenth ,avenue was on an earth foundation1 it was necessary to underpin it before the excavation could be done4 ,the building was supported on needles1 and rubble masonry was put in from the bottom of the old foundation to the rock4 ,the foundation of #dac ,west #cast ,street1 immediately west of the ,express ,building site1 was of very poor masonry1 and it was necessary to rebuild it prior to taking out the adjoining excavation4 ,illustration3 ,,plate ,l1 ,,fig4 #a4--,,tw #bc1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,view looking ,eastward from ,tenth ,ave41 showing work between ,ninth ,tenth ,avenues4 ,dec4 #bf1 #jf4 ,illustration3 ,,plate ,l1 ,,fig4 #b4--,,tw #ce1 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,view looking ,northwest from ,sta4 #ahd1 #abj feet ,south of center line4 ,dec4 #ca1 #jg4 ,illustration3 ,,plate ,l1 ,,fig4 #c4--,,tw #if1 ,p4,t4 ,t4,r4,r4 ,co4 ,n4,r4 ,div4 ,terminal ,station ,west4 ,view looking ,west from ,ninth ,avenue ,elevated ,railway1 showing condition of work4 ,may #bf1 #ji4 ,illustration3 ,,plate ,l1 ,,fig4 #d4--,,tw #ajd1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,view from ,tenth ,avenue looking ,east1 showing progress of concrete walls4 ,aug4 #g1 #ji4 ,along the north side1 between ,stations #ahf #ej and #ahg #ej1 the walls supporting the adjoining back yards were of poor quality and had to be renewed by the contractor before excavation could be done4 ,the excavated material was loaded by derricks on cars at the top of the excavation1 these cars being on tracks having a direct connection with the disposal trestle1 as shown by ,fig4 #a1 ,plate ,l4 ,as soon as it could be done1 derricks were placed at the bottom of the excavation2 tracks were then laid out there1 and the excavated material was loaded on cars at the bottom and hoisted by derricks to cars on the disposal trestle4 ,a locomotive was lowered to the bottom of the excavation on ,august #beth1 #aijg1 and a derrick started operating at the bottom on ,august #bgth1 #aijg4 ,the commencement of this work by derricks at the bottom is shown by ,fig4 #c1 ,plate ,,lii4 ,in general1 the disposal tracks were maintained about on the center line of #cast ,street until the excavation had been carried as close to them as possible1 and on ,october #afth1 #aijg1 they were shifted to the extreme north side of the work1 as shown by ,fig4 #b1 ,plate ,l4 ,a portion of the old trestle was left in place near ,tenth ,avenue1 a derrick was erected thereon1 and the tracks were used for cars to receive the excavated material hoisted from sub-grade4 ,the disposal trestle was maintained in this position until such time as it would interfere with the excavation1 and then the tracks were abandoned4 ,this was done on ,november #aath1 #aijh4 ,fig4 #c1 ,plate ,l1 shows the finishing of the excavation on the north side of the work4 ,on ,august #cjth1 #aijh1 a cut was made under ,ninth ,avenue at sub-grade1 and cars could then be run from ,seventh to ,tenth ,avenue at sub-grade4 ,on ,october #bdth1 #aijh1 the connection with the disposal trestle east of ,ninth ,avenue was abandoned1 and all excavated material was hoisted from sub-grade at ,tenth ,avenue by derricks4 ,as previously stated1 the contractor was required to make complete disposal of all excavated material after ,january #ast1 #aiji1 but was allowed the use of the pier until ,january #bjth1 #aiji1 after which date the materials were hoisted by derricks at ,tenth ,avenue1 loaded on #b-;horse trucks1 and transported to the #cjth ,street pier1 ,north ,river1 where it was loaded on scows by two electric derricks4 ,a considerable amount of the rock excavation was broken up and used for back-fill4 ,earth ,excavation4--,practically all the earth excavation1 amounting to about #eg1jjj cu1 yd41 was done with steam shovels4 ,the average quantity of earth excavated by a steam shovel per #aj-;hour shift was #ahj cu4 yd4 ,this material was loaded on side-dump cars and taken to the disposal pier where it was dumped through chutes to the decks of scows4 ,inasmuch as the quantity of earth excavation was small1 as compared with the rock1 the earth was used principally for the first layer on the scows for padding1 so that small stones might be dumped through the chutes without injuring the decks4 ,rock ,excavation4--,as previously stated1 the rock broke better on the south than on the north side1 where there were several slides1 and considerable excavation had to be taken out beyond the neat line required in the specifications4 ,the worst slide occurred at midnight on ,july #c;d1 #aiji1 at about ,station #ahh #ej4 ,the last blast1 to complete the excavation to sub-grade at this point1 had been fired in the afternoon of the same day1 and the mucking was practically completed4 ,great care had been taken in excavating near this point1 as it was evident that the rock was not of a very stable character1 but1 when the excavation had been completed1 it was thought that the rock remaining in place would stand4 ,the volume of material brought down by this slide amounted to about #bjj cu4 yd4 ,the rock on the south side broke very well1 and there were no slides of any consequence4 ,the drill holes were laid out by the blaster1 and the general method of drilling for different classes of work was as follows3 ,in breaking down1 the holes were started about #h ft4 apart1 on a slight batter1 so that at the bottom they would be considerably less than #h ft4 apart4 ,they were drilled about #aj ft4 deep1 and blasting logs were used1 as it was necessary to load quite heavily in order to lift the material and start the cut4 ,after the cut had been made1 side holes were shot to widen out sufficiently to start another cut4 ,after a side cut about #bj ft4 deep had been made1 the side holes were drilled #bj ft4 deep1 and the holes were loaded and tamped for the full #bj-;ft4 cut4 ,under the terms of the specifications1 the contractor was required to complete the excavation on the sides by drilling broaching holes4 ,the maximum length of drill steel was about #bj ft41 and1 where the excavation plane of broaching was more than #bj ft4 in depth1 the contractor was permitted to start the holes back of the broaching line1 in order to allow for setting up the drills on the second lift4 ,a distance of about #h in4 was usually allowed for setting up a drill4 ,the broaching line was painted on the surface of the rock in advance of the drilling1 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 batter4 ,holes were also drilled in front of this broaching line1 and1 when the excavation had been taken out to within about #f ft4 in front of it1 the holes immediately in front were loaded1 and also about every third one of the broaching holes1 and1 unless the rock was very bad1 it usually broke sharply at the broaching line4 ,occasionally1 the broaching holes which were not loaded were filled with sand1 which gave rather better results than leaving them open4 ,in the steam-shovel work on the east side of ,ninth ,avenue1 spring holes were used4 ,they were formed by drilling a #bj-;ft4 hole and exploding at the bottom of it1 without tamping1 two or three sticks of dynamite1 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 #ajj to #bjj lb4 of dynamite4 ,face holes and breast holes were also drilled1 and it was possible by this method to drill and break up a cut #bj ft4 deep and #ae ft4 thick4 ,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 line4 ,from the best records obtainable1 the average progress in drilling was about #cc lin4 ft4 per #h-;hour shift4 ,the average number of cubic yards of excavation per drill shift was #ac4i1 and the average amount of drilling per cubic yard of excavation was #b4d ft42 this covered more than #bg1jjj drill shifts4 ,the dynamite was practically all #fj1 and the average excavation per pound of dynamite was #b4b cu4 yd4 ,the contractor employed an inspector of batteries and fuses1 who1 using an instrument for that purpose1 tested the wiring of each blast prior to firing1 in order to discover any short circuits1 and thus prevent the danger of leaving unexploded dynamite in the holes4 ,the average quantity of excavation per derrick shift of #aj hours1 covering #g1djj shifts1 #hg of the excavation being rock1 was #ej cu4 yd41 and the average force per shift1 including only foreman and laborers1 was #ac men4 ,it was found that a derrick operating at the top of a #bj-;ft4 cut would handle about #dj cu4 yd4 per shift1 whereas1 if operating at the bottom of the cut1 it would handle about #fj cu4 yd4 per shift4 ,the elevator derricks at ,tenth ,avenue were very efficient1 and each could take care of the material from four derricks at the bottom1 hoisting #bej cu4 yd4 per shift a height of #fj ft4 ,concrete ,retaining and ,face ,walls4--,it was essential to have the greatest space possible at the bottom of the excavation1 and1 inasmuch as the yard was to be left open1 it was necessary to provide some facing for the rock on the sides in order to prevent disintegration1 due to exposure1 and give a finished appearance to the work4 ,above the rock surface a retaining wall of gravity section was designed1 the top being slightly higher than the yards of the adjoining properties4 ,the face wall was designed to be as thin as possible1 in order to allow the maximum space for tracks4 ,the excavation1 therefore1 was laid out so that the back of the retaining wall would not encroach on the adjoining property1 but would practically coincide with the property line at positions of maximum depth4 ,the batter on the face of the wall was #b in4 per ft41 and a bridge seat #c-a_/b ft4 wide was formed at an elevation of #bb ft41 minimum clearance1 above the top of the rail4 ,this bridge seat was made level4 ,the maximum height of the south wall is #di ft41 and of the north wall #fe ft4 ,the face walls were classed as ,upper ,face ,walls1 extending from the base of the retaining wall to the bridge seat1 and as ,lower ,face ,walls1 extending from the bridge seat to the base of the wall4 ,the general design is shown on ,fig4 #h4 ,in considering the design of the face wall it was felt that1 the wall being so thin1 ample provision should be made to prevent any accumulation of water and consequent pressure back of the wall2 therefore1 no attempt was made to water-proof it1 but provision was made to carry off any water which might appear in the rock4 ,box drains1 #b ft4 wide and #f ft4 from center to center1 were placed against the rock1 so that1 there being but #d ft4 between the drains1 and the wall having a minimum thickness of #b ft41 any water in the rock would not have to go more than #b ft4 to reach a drain1 and would probably pass along the face of the rock to a drain rather than through #b ft4 of concrete4 ,these drains were connected with pipes leading through the wall at its base4 ,illustration3 ,,fig4 #h4 7,full page image7 ,,retaining ,,and ,,face ,,walls ,,north ,,side ,these box drains occurred so frequently1 and decreased the section of the wall so materially1 that it was thought desirable to tie the wall to the rock4 ,this was done by drilling into the rock holes from #f to #ae ft4 in depth1 and grouting into each hole a #a-a_/b-;in4 rod having a split end and a steel wedge4 ,the outer end of each rod was fitted with a #ab by #ab by #a_/b-;in4 plate and a nut1 and extended into the wall1 thus tying the concrete securely to the rock4 ,the drains being #f ft4 from center to center1 the tie-rods were placed midway between them1 and #f ft41 from center to center1 vertically and horizontally4 ,fig4 #h shows the arrangement of these rods and drains4 ,around the ,express ,building site1 just west of ,ninth ,avenue1 on the south side of the work1 the bridge seat was omitted1 and the face wall was designed #b ft4 thick from top to bottom4 ,the batter on the #cast ,street wall was made variable1 the top and bottom being constant distances from the center line and on different grades4 ,the retaining walls were water-proofed with three layers of felt and coal-tar pitch1 which was protected by #d in4 of brick masonry4 ,a #f-;in4 vitrified drain pipe was laid along the back of the wall1 with the joints open on the lower half1 and this was covered with #a ft4 of broken stone and sand before any back-fill was placed on it4 ,the arrangement of the drains was as follows3 ,the #f-;in4 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 #bd ft41 and this ran through the base of the retaining wall4 ,midway between these pipes1 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 above4 ,all the box drains1 except those connected with the drains back of the retaining wall1 were sealed at the elevation of the base of the retaining wall1 as noted previously4 ,the specifications required vitrified pipe to be laid through the retaining wall1 but1 owing to the difficulty of holding the short lengths of pipe in place during the laying of wet concrete1 they were dispensed with1 and either iron pipes or wooden boxes were used4 ,tie-,rods4--,when the excavation on the sides had been completed1 movable drilling platforms were erected1 as shown by ,fig4 #d1 ,plate ,l4 ,the holes were drilled on a pitch of #b in4 per ft4 with the horizontal4 ,the depths of the holes were decided by the engineer1 and were on the basis of a minimum depth of #e ft4 in perfect rock2 the character of the rock1 therefore1 and the presence of seams1 determined the depths of the holes4 ,each hole was partly filled with grout1 and the rod1 with the steel wedge in the split end1 was inserted and driven with a sledge so that the wedge1 striking the bottom of the hole first1 would cause the split end of the rod to open4 ,each hole was then entirely filled with neat cement grout4 ,box ,drains4--,various methods of forming the box drains were considered1 such as using half-tile drains1 or a metal form1 or a collapsible form which could be withdrawn1 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 mortar4 ,these boxes were left in place4 ,fig4 #a1 ,plate ,,li1 shows the tie-rods and box drains in place1 and holes being cut near the bottom of the drains for the pipes leading through the wall4 ,forms4--,fig4 #a1 ,plate ,,li1 shows the form used on the south side of the work4 ,the materials were of good quality1 and the form1 which was about #ej ft4 long1 was used to build twelve sections1 or about #fjj ft4 of wall4 ,the form was tied in at the top and bottom by cables attached to rods drilled into the rock1 and it was thought that1 with the trusses to stiffen the middle section of the form1 it would not be necessary to use raker braces against it4 ,this would have been desirable1 as the placing of the raker braces took considerable time4 ,it was found1 however1 that the form was not sufficiently rigid1 as it bulged at the middle section and could not be held by the trusses4 ,two or three sets of raker braces1 about #ab ft4 apart1 were used1 and in addition1 rods with turnbuckles were placed through the form and fastened to the tie-rods1 and thus the form was held in place successfully4 ,on the forms built later1 the trusses were omitted1 and raker braces1 about every #f ft41 were used4 ,the rods which screwed into the turnbuckles were removed before the form was moved4 ,the photograph1 ,fig4 #d1 ,plate ,,lii1 was taken inside the concrete form for the lower face wall on the north side1 and shows the drains leading through the wall1 the turnbuckles attached to the tie-rods1 the cables attached to rods in the rock1 and the braces to keep the form from coming in2 these braces1 of course1 were removed as the concrete came up4 ,the form was built low and wedged up into position4 ,after a section of concrete had set sufficiently1 the wedges were knocked out1 the form was lowered and moved from the wall1 and was then moved along the lowest waling piece by block and tackle to its new position4 ,fig4 #d1 ,plate ,l1 shows the forms used on the north side of the work4 ,a section1 #a ft4 square1 at the top of the bridge seat of the lower face wall1 was left out1 so that the bottom of the form for the upper face wall could be braced against it4 ,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 form2 braces were also put in from the back of the retaining wall form to the walls of buildings along the property lines1 when this could be done4 ,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 rock1 as was also done in the case of the lower face wall4 ,it was generally possible to hold the form to true position in this manner1 but occasionally it had a tendency to bulge2 when this occurred1 the rods leading through the form and fastened to the tie-rods were tightened up1 the placing of the concrete was slowed up1 and no serious bulging occurred4 ,bulkheads at the ends of the sections were built of rough planking securely braced to the rock1 except that a planed board was laid up against the face of the form to make a straight joint4 ,at the end of each section a ,v was formed1 as shown by ,fig4 #a1 ,plate ,,li4 ,at all corners1 a return1 or portion of the wall running at right angles1 was built1 and no section of wall was stopped at a corner4 ,filling ,forms of ,lower ,face ,walls4--,a temporary trestle was erected above the elevation of the bridge seat1 and a track1 leading from the mixer to the form to be filled1 was laid on it4 ,at the commencement of each section a layer of mortar 7#a part of cement to #b-a_/b parts of sand7 was deposited on the bottom4 ,a #a3c3f mixture of concrete was used2 it was run from the mixer into dump-cars and deposited in the form through chutes1 three of which were provided for each #ej-;ft4 section1 the average length4 ,the concrete was mixed wet1 and was not rammed2 the stone was spaded back from the face1 and no facing mixture or facing diaphragms were used4 ,work on each section was continued day and night without any intermission from the time of commencement to the time of completion4 ,at frequent intervals the box drains were washed out thoroughly with a hose1 in order to prevent them from clogging up with grout4 ,illustration3 ,,plate ,,li1 ,,fig4 #a4--,,tw #ff1 ,p4,n4,y4 ,l4,i4,r4,r4 ,terminal ,station ,west4 ,box drains and tie rods1 ,south side1 ,sta4 #ahdhj to #ahead4 ,sept4 #ag1 #jh4 ,illustration3 ,,plate ,,li1 ,,fig4 #b4 ,illustration3 ,,plate ,,li1 ,,fig4 #c4--,p #df4 ,p4,r4,r4 ,tunnels1 ,n4,r4 ,div4 ,sect4 ,gy4 ,west4 ,disposal trestle just before demolition4 ,view of ,south side showing chutes4 ,jan4 #ba1 #ji4 ,illustration3 ,,plate ,,li1 ,,fig4 #d4--;,a #ed4 ,p4,r4,r4 ,tunnels1 ,n4,r4 ,div4 ,sect4 ,gy4 ,west ,oj4 ,view across ,north ,river on line of ,tunnels1 looking from ,new ,york to ,new ,jersey4 ,feb4 #i1 #jg4 ,in the first few sections of wall1 the form was filled to within #a in4 of the top of the bridge seat and allowed to set for about #b hours2 it was then finished to the proper elevation with a plaster of #a part of cement to #a part of sand4 ,this did not prove satisfactory1 as there were indications of checking and cracking1 and1 later1 the form was filled to the required elevation and the surface floated4 ,the form was allowed to remain in place for from #ah to #bd hours1 depending on the weather4 ,in most cases1 immediately after the form had been moved1 a scaffold was erected against the face of the wall1 and the face was wet and thoroughly rubbed1 first with a wooden float and then with a cement brick1 until the surface was smooth and uniform4 ,the section #a ft4 square at the top of the bridge seat1 which was left out in order to brace the bottom of the form for the upper face wall1 was filled in after the walls had been completed4 ,the old concrete was very thoroughly cleaned before the new concrete was placed on it1 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 walls4 ,in hot weather the walls were thoroughly wetted down several times a day for several days after the form had been removed4 ,upper ,face and ,retaining ,wall4--,in cases where the top of the retaining wall was at a higher elevation than the mixer1 it was necessary to raise the concrete in a bucket with a derrick1 and dump it into cars on the trestle above the top of the coping4 ,concrete was deposited through chutes1 as in the lower face wall1 continuously from the bottom of the face wall to the top of the retaining wall4 ,at the commencement of each section of the retaining wall a layer of mortar was put on the rock4 ,a #a3b3c mixture of concrete was used in the face wall1 and a #a3c3f mixture in the retaining wall4 ,as the face walls were so thin1 the number of batches of concrete per hour was reduced1 for the form filled so rapidly that the concrete1 before it set1 exerted an excessive pressure against the form1 and this tended to make it bulge4 ,the proper rate at which to place the concrete behind a form #ej ft4 long1 with a wall #b ft4 thick1 was found to be about fifteen #a_/b-yd4 batches per hour4 ,cracks in ,walls and ,longitudinal ,reinforcement4--,before the concrete walls were started1 the contractor suggested using forms #ajj ft4 long and building the walls in sections of that length2 it was decided1 however1 to limit the length to #ej ft4 ,the south walls1 in sections approximately #ej ft4 long1 were built first1 starting at ,tenth ,avenue and extending for about #ejj ft4 ,soon after the forms were removed1 irregular cracks appeared in the walls between the joints in practically every section4 ,it was thought that these cracks might be due to the wall being very thin and being held at the back by the tie-rods2 there was also quite a material change in the section of the wall at each drainage box4 ,although it was admitted that these cracks would have no effect on the stability of the wall1 it was thought that1 for appearance sake1 it would be desirable to prevent or control them1 if possible4 ,the first method suggested was to shorten the sections to #be ft41 which would give an expansion and contraction joint every #be ft41 it being thought that sections of this length would not crack between the joints4 ,this1 however1 was not considered desirable4 ,an effort was then made to prevent cracks in a section of wall1 about #df ft4 long1 on the south side1 by using longitudinal reinforcement4 ,in the lower and upper face walls1 #c_/d-;in4 square twisted steel rods were placed longitudinally about #d in4 in from the face and about #a ft4 #d in4 apart vertically4 ,the sections of these walls were finished on ,april #ajth1 and ,may #eth1 #aiji1 respectively4 ,at present there are no indications of cracks in these sections1 and they are practically the only ones in the south walls which do not show irregular cracks4 ,it was decided1 however1 that1 inasmuch as the cracks did not affect the stability of the walls1 the increased cost of thus reinforcing the remaining walls was not warranted4 ,an effort to control the cracks was made by placing corrugated-iron diaphragms in the form1 dividing each #ej-;ft4 section into three parts4 ,the diaphragms were #a ft4 wide1 and were placed with the outer edge #a in4 in from the face of the wall1 but in the copings they were omitted4 ,the purpose of these diaphragms was to provide weak sections in the walls1 so that if there was any tendency to crack it would occur along the line of the diaphragms4 ,corrugated iron was used for the diaphragms instead of sheet iron as it was more easily maintained in a vertical position4 ,the general arrangement of the diaphragms is shown on ,fig4 #d1 ,plate ,,lii4 ,the results obtained by using diaphragms have been quite satisfactory1 and cracks approximately straight and vertical have usually appeared opposite the diaphragms soon after the forms were removed4 ,diaphragms were used on all the remaining walls1 with the exception of those between ,stations #ahg #jg and #ahh #hc on the north side1 where the rock was of poor character and bad slides had occurred4 ,between these points1 in order to strengthen the wall1 twisted steel rods1 #a in4 square1 were placed longitudinally1 #f in4 in from the face of the wall and #b ft4 apart vertically1 between ,elevations #bie and #cce4 ,illustration3 ,,plate ,,lii1 ,,fig4 #a4--;,,girders ,,under #i,,th ,,avenue ,,elevated ,,railroad4 ,illustration3 ,,plate ,,lii1 ,,fig4 #b4--,,tw #ajj4 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,showing excavation of completion of ,south abutment #ith ,ave4 and method of ,supporting ,elevated ,railway ,column #dhh4 ,july #ba1 #ji4 ,illustration3 ,,plate ,,lii1 ,,fig4 #c4--,,tw #ca4 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,view showing excavation #ith and #ajth ,avenues ,south of #cbnd ,st4 looking ,west from ,sta4 #ahd4 ,aug4 #ag1 #jg4 ,illustration3 ,,plate ,,lii1 ,,fig4 #d4--,,tw #aja4 ,p4,t4 ,t4,r4,r4 ,co4 ,terminal ,station ,west4 ,inside of concrete form for lower-face wall1 showing drains1 tie rods1 diaphragms and methods employed for tying in the form in addition to braces outside4 ,july #ba1 #ji4 ,tenth ,avenue ,portal4--,the design of the ,tenth ,avenue ,portal is shown on ,fig4 #i4 ,the stone selected came from the ,millstone ,granite ,company's ,quarries1 ,millstone ,point1 ,conn41 and is a close-grained granite4 ,fig4 #b1 ,plate ,,li1 shows the completed portal4 ,practically all the stone cutting was done at the quarry1 but certain stones in each course were sent long and were cut on the ground1 in order to make proper closures4 ,drains were left behind the portal around the back of each arch1 leading down to the bottom1 and through the concrete base at each side of the portal and in the central core-wall2 all these drains have been discharging water4 ,power-,house4--,the old church at ,no4 #bcf ,west #cdth ,street1 between ,seventh and ,eighth ,avenues1 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-,west4 ,four straight-line compressors and one cross-compound ,corliss compressor were installed1 the steam being supplied by three ,stirling boilers4 ,three electrically-driven air compressors1 using current at #f1fjj volts1 were also installed1 and the total capacity of the power-house was about #ai1jjj cu4 ft4 of free air per minute compressed to #ij lb4 per sq4 in4 ,disposal ,pier4--,the disposal pier 7old ,no4 #fb and new ,no4 #gb71 at the foot of ,west #cb;d ,street1 ,north ,river1 was leased by the ,pennsylvania ,railroad ,company4 ,the entire pier1 with the exception of the piles1 was taken down1 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 purposes4 ,subsequent to the driving of the tunnels there was a considerable settlement in the pier1 especially noticeable at the telphers1 and finally these had to be abandoned on this account4 ,fig4 #c1 ,plate ,,li1 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 rock4 ,fig4 #d1 ,plate ,,li1 shows the derricks at the end of the pier4 ,these were used1 not only for loading heavy stones and skips1 but also with a clam-shell bucket for bringing in broken stone and sand for use in the work4 ,large quantities of pipe1 conduits1 brick1 etc41 were also brought to this pier for use on the work4 ,illustration3 ,,fig4 #i4 7,full page image7 ,,portal1 ,,retaining ,,and ,,face ,,walls1 ,,tenth ,,avenue ,,organization ,,of ,,engineering ,,force ,,in ,,field4 ,the design and execution of the work were under the direction of ,charles ,m4 ,jacobs1 ,m4 ,am4 ,soc4 ,c4,e41 ,chief ,engineer1 and ,james ,forgie1 ,m4 ,am4 ,soc4 ,c4,e41 ,chief ,assistant ,engineer4 ,the writer acted as ,resident ,engineer4 ,illustration3 ,fig4 #aj4 ,the general organization of the engineering force in the field is shown by the diagram1 ,fig4 #aj4 ,the position of ,assistant ,engineer1 in responsible charge of ,construction and ,records1 has been filled in turn by ,messrs4 ,a4,w4 ,gill1 ,n4,c4 ,mc,neil1 ,jun4 ,am4 ,soc4 ,c4,e41 and ,w4,s4 ,greene1 ,assoc4 ,m4 ,am4 ,soc4 ,c4,e4 ,messrs4 ,a4,p4 ,combes and ,t4,b4 ,brogan have acted as ,chief ,inspector and ,night ,inspector1 respectively1 in charge of outside work during the entire carrying out of the contract4 ,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 ,avenue1 and these lines1 together with bench-marks similarly established1 were used in laying out the ,terminal ,station-,west work4 ,prior to the commencement of the work1 elevations were taken on the surface at #aj-;ft4 intervals1 and elevations of the rock surface were taken on these points as the rock was uncovered4 ,cross-sections were made and used in computing the progress and final estimates4 ,very careful records were kept of labor1 materials1 derrick performances1 steam-shovel performances1 quantity of dynamite used1 etc41 and1 in addition1 a diary was kept giving a description of the work and materials used each day2 various tables and diagrams were also prepared4 ,a daily report was sent to the ,chief ,office showing the quantities of excavation removed and concrete built1 the force in the field1 the plant at work1 etc41 during the previous day4 ,at the end of each month a description of the work done during that month1 with quantities1 force of men employed1 percentages of work done1 etc41 was sent to the ,chief ,office4 ,two diagrams1 showing cross-sections and contours of the excavation done and the progress of the concrete walls1 were also sent4 ,,cost ,,account4 ,from the records of labor and material obtained in the field1 and from estimated charges for administration and power1 an estimate was made of the cost to the contractor for doing various classes of work4 ,it was necessary to estimate the administration and power charges1 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-grade4 ,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 7which included superintendence1 lighting1 etc47 were apportioned to the various classes of work in proportion to the value of the labor done4 ,,statistics4 ,the total weight of the structural steel used during the underpinning of ,ninth ,avenue was #a1dge1jjj lb4 ,the total weight supported during the work under ,ninth ,avenue was about #e1jjj tons4 ,u#a;,e,the average daily traffic over the ,ninth ,avenue ,elevated ,railway was #ij1jjj passengers1 and1 during the progress of the excavation and underpinning1 about #ajj1jjj1jjj passengers were carried over that structure4 ,the total excavation was #eba1jjj cu4 yd41 of which #hg was solid rock4 ,the average drill performance was about #cc lin4 ft4 per #h-;hour shift4 ,the average number of cubic yards of excavation per drill shift was #ac4i4 ,the average number of feet of drilling per cubic yard of excavation was about #b4d4 ,the average excavation per pound of dynamite was #b4b cu4 yd4 ,the average amount of excavation per derrick shift of ten hours1 #hg of the excavation being rock1 was #ej cu4 yd4 ,the average derrick force per shift1 including only foreman and laborers1 was #ac men4 ,the salaries of the engineering staff in the field and the expenses of equipping and maintaining the field office amounted to #b4h of the cost of the work executed1 #b4g being for engineering salaries alone4 ,,footnotes3 ,footnote ,a3 ,presented at the meeting of ,april #fth1 #aiaj4