Scientific American · September 27th, 1902 · pp. 197, 198, 202-203.

The work of constructing the Rapid Transit Subway in this city had not been long under way before the engineers confidently predicted that cars would be running by Christmas of 1903. That was nearly two years ago; and the progress of the work in the interval has been so satisfactory that the early opening of the road Is to-day more certain than ever. With the exception of the huge irrigation dam in Egypt, illustrated in our last issue, we know of no other great engineering work of modern times that will have been completed many months before the contract date. It is unfortunate for New York city that similar dispatch has not been shown on some other municipal improvements, notably the Croton Dam, the Jerome Park Reservoir, the new East River Bridge and its successor, Bridge No. 3, all of which have been allowed to drag wearily along, the speed of construction being apparently left entirely to the inclination of the contractors. According to figures furnished to the Scientific American by the Chief Assistant Engineer of the Rapid Transit Commission, Mr. George S. Rice, out of a total estimated cost of $35,000,000, $21,000,000 has been paid out to date, and judged on this basis the road may be said to be sixty per cent completed. Out of a total earth excavation of 1,700,000 cubic yards, 1,580,000 cubic yards, or 93 per cent, has been taken out. Of a total rock excavation of 1,300,000 cubic yards, 862,000 yards has been excavated, leaving 34 per cent yet to be done, A most important item as affecting the completion of the work is the delivery of steel, of which 65,000 tons are required. Up to date some 40,000 tons, or 62 per cent, has been delivered. In estimating the time necessary for completion it should be borne in mind that the remaining work will be put through with greater celerity than that which has been already done, for the reasons that the plant is on the ground, valuable experience as to best methods of doing the work has been gained, and everything is in smooth working order.

The Rapid Transit Subway, New York

The construction of the great twenty-one mile system of underground railway known as the New York Rapid Transit Subway would be a notable feat of engineering, even if it were being built under what might be called normal conditions of traffic, such as may be found in the outlying and less thickly populated suburbs; but as a matter of fact, the difficulties of the work have been enormously increased by the condition that practically the whole of the tunnel lies immediately beneath the double tracks of the busiest street surface trolley lines in the city. These tracks being of the underground trolley type are extremely heavy in construction, while most of the cars which traverse them are of the largest and heaviest type, and run under an unusually close headway, it being no uncommon thing for three or four cars to be on one block at the same time. Moreover, the subway lies, as we have said, for the greater part of its length beneath some of the principal arteries of vehicular traffic in the city, and it was laid down as one of the strict conditions imposed upon the contractors, that there must be no interference whatever with the operation of the electric tracks, and the least possible obstruction to ordinary street traffic. The problem of carrying the electric tracks while the solid ground beneath them was being cut away was no ordinary one, and considerable ingenuity has been shown in working it out. On the front page of this issue will be found a cross section taken on Fourth Avenue, showing the means adopted for supporting the trolley tracks and also the great number of gas, water and electric mains, while the earth and rock were being excavated, the steel framing built in place, and the concrete covering and the back filling and surface filling put in.

The method of carrying the electric tracks was as follows: At the level of the street surface two pairs of 24-inch I-beams, 2 feet in depth and about 35 feet in length, were placed parallel with the tracks, one pair on each side thereof. At each end of the I-beams 12 x 12 posts were sunk to a firm foundation, and for the length of track covered by the I-beams the soil beneath the yokes carrying the tracks was dug out, and 12 x 12 timbers placed underneath them crosswise to the track. Heavy bolts were then passed up from the ends of the transverse timbers to the top flanges of the I-beams and drawn up snugly by nuts, the load of this stretch of track with the cars upon it being thus transferred to the I-beams. Similarly, 12 x 12 supporting timbers were placed from the I-beams to the adjoining sidewalks on either side, one end being bolted to the I-beams and the other resting upon the sidewalk flagging. The material was then excavated by pick and shovel, dumped into buckets of an overhead cableway, loaded into carts and taken to some convenient dumping ground. The timbers extending from the I-beams to the sidewalks served to hold in place and carry during the progress of excavation the numerous water, gas and electric mains, which lie immediately below the surface of the street. These were slung from the beams by stout chains, which held them securely in their proper level and alignment during the work of excavating. As the excavation was carried down, additional and longer 12 x 12 posts were put in place until subgrade was reached. The foundation blocks and concrete floor were laid and the steel columns and the I-beams of the roof erected, the side walls and the intervening arches of concrete built in place, and the back filling rammed in, completing the work. As the filling was brought up to grade, the chains supporting the gas and water mains were unslung and the 12 x 12 timbers removed, the surface of the street being finally restored to its original condition. The steel framing is spaced about 5 feet apart longitudinally and answers in some sense to the framing ribs of a modern steamship. The concreting between the side posts and between the I-beams of the roof is built in arched form to enable it better to resist the crushing pressure to which it is subjected.

The accompanying plan showing the progress of the work to date will be of considerable interest. On those portions of the road covered by heavy black lines, the work of excavation has been completed, while the intervening gaps represent the work that has been only partially excavated. Commencing at the loop under City Hall Park, we find that the excavation has been entirely completed, and, indeed, very little remains to be taken out, if we except the large station at the Brooklyn Bridge, as far north as Pearl Street. From Pearl Street to just below Canal Street but little work has been done. It was anticipated that on account of this ground having originally been a swamp, there would be considerable trouble with water, for which reason this particular stretch of line was left until the last. The contractors, however, are not experiencing any abnormal difficulty, and it is likely that the intervening gap of a few blocks will be completed by the fall of next year. From Canal Street to Astor Place the Subway has been entirely excavated, practically the whole of the steel work and concreting is done, and before many months the surface of Elm Street will have been repaved and put in first-class condition. From the south side of Astor Place to Ninth Street no excavation has been done, there being some dispute with the owners of the buildings underneath which the tunnel at this point will have to pass. From Ninth Street the excavation is complete, the steel work is in and most of the concreting completed to Fourteenth Street, where more than half of the excavation for the large Fourteenth Street station has been done and the balance of the work is being pushed forward with great dispatch. From Fourteenth Street to Seventeenth Street the solid rock has been excavated for three out of the four tracks, the steel has been put in, and the street restored to its original condition. Most of the excavation has been done for the Eighteenth Street station, and for the block immediately to the north of it. From Nineteenth Street to Twenty-third Street the work is nearly finished, as is the excavation for the Twenty-third Street station, which is about ready for the insertion of the steel framework. From Twenty-third Street to Thirty-third Street there is a practically unbroken stretch of completed Subway. The excavation is still going on for the Thirty-third Street station, and at the portal of the two-track tunnels which extend from Thirty-third Street to Forty-second Street. On both the east and west side branches of the tunnel on this stretch excavation is completed, and about half of the concrete lining has been put in place.

There is a gap of about one block opposite Vanderbilt Avenue on Forty-second Street, most of it solid rock work, upon which no work of excavation has been done; but from just west of Vanderbilt Avenue to Broadway the stretch of line through Forty-second Street is about three-quarters excavated, and a large amount of the steel work is in place and concreted up. There is another gap at Forty-second Street and Broadway, where work is being delayed by a dispute with the property owners, and but little work has been done as yet at Long Acre Square. From Forty-fifth Street to Seventy-second Street there is the longest stretch of completed line on the whole system. With a few exceptions this work is not only excavated, but the steel is in and concreted up and the street surface is largely restored. From Seventy-second Street to Eighty-first Street the work is somewhat backward. In places the ground is scarcely broken and there is here much work yet to be done. From Eighty-first Street to 100th Street, excavation is completed and much steel in place. There is considerable work to be done for two blocks south of 104th Street, where the four-track road divides into its western and eastern branches. From 104th Street to 110th Street on the west branch, the excavation is completed in stretches, while there are one or two blocks on which much work remains to be done. From 110th Street to Manhattan Valley excavation is practically completed, while about three quarters of the elevated structure across the Valley has been erected, and only awaits the delivery of the 160-foot steel arch over Manhattan Street to enable this fine viaduct to be completed. At present the structure is painted red, but ultimately, when it has been given its coating of olive green, it will present a thoroughly attractive appearance. The design of the bridge is more open and less cumbersome than the adjoining Riverside viaduct, and architecturally it will harmonize well with its surroundings.

North from the Manhattan viaduct to 149th Street the greater part of the excavation has been done, although there are occasional stretches on which merely the looser surface material has been taken out and the bulk of the rock work is untouched. It is but fair to add that on this section from 139th Street to 144th Street the magnitude of the work has been greatly increased over the original design, owing to the intention of forming here a large underground storage station for trains. The width of the excavation has been doubled from 50 to 100 feet, and over this stretch of line will be eight parallel tracks. There are portions of the line on which no excavation has yet been done, for the reason that the contractor is completing the steel work on a given stretch of line, so that when he comes to excavate the adjoining section, he can use the material taken out for back filling and surface filling on the finished structure. Practically the whole of the excavation of the solid rock tunnel from 150th Street to 186th Street has been completed, while about 500 feet of tunnel has been driven from the northerly slope of Washington Heights at Fort George southward along the route of the tunnel. Between the shaft at 181st Street and the entrance to the tunnel at Fort George is a distance of 4,338 feet. Of this 1,450 feet have been driven northward from 181st Street and this in addition to the 500 feet driven southwest from Fort George leaves 2,488 feet yet to be tunneled. At the rate of 100 feet a month which is now being made, this part of the tunnel should be completed in about two years' time, or a little before contract date.

On the easterly branch of the system the tunneling from 103d Street beneath Central Park to Lenox Avenue has been completed and the open excavation from 110th Street and Lenox Avenue to 141st Street is almost all done. Over most of this section the steel and concrete work is completed and the street surface restored. From 141st Street to the Harlem River the work of excavation is in progress. The crossing of the Harlem is an extremely interesting piece of work. It is being done by dredging and by the use of cofferdams of 12 x 12 sheet piling. Most of the preliminary dredging has been done across the river, and about half the width has been covered by a cofferdam, the pumping out of which is now in progress. In the Mott Haven district the Subway for some eight or ten blocks is in course of excavation, and a large amount of work has been done; while the foundations for the elevated structure have all been built from Jackson Avenue up to the Bronx Park.

While the building of the line is making good progress, it is satisfactory to note that the provision of motive power and equipment is also being pushed along expeditiously. The great power house between Fifty-eighth and Fifty-ninth Streets and Eleventh and Twelfth Avenues is making fair progress, the foundation having been completed, while the plans for the buildings and machinery have been definitely settled, and the contracts are being executed. Eight 7,500 horse power engines direct-connected to eight 5,000 kilowatt generators will form the initial equipment, the power house property being large enough to admit of additions as there shall be a demand for them. The General Electric and Westinghouse Companies are competing for the important contract of furnishing the cars, of which 600 will be called for at the opening of the line. In about a month's time, tests will be made of specimen cars which have been built by these companies, illustrations of which are given on our front page of this issue. The specifications called for a multiple-control system, three cars out of five, or with five cars out of seven or eight in a train being motor cars. Provision has already been made for the rail-laying to the extent of letting a contract to the Pennsylvania Steel Company for 10,000 tons of rail, weighing 100 pounds to the yard. In this connection it is well to suggest to the engineers of the Rapid Transit Subway that they should carry out exhaustive tests on different systems of track to ascertain which will be the least noisy for use in the tunnel. With the heavy local traffic and with express trains thundering through the tunnel at speeds of 50 miles an hour and over, it is likely at best to be a very noisy place, and care should be taken to adopt that system of ties and track which will give the most silent running.

Photo Gallery

Five Random Images
Image 52579 (141k, 1024x413) Photo by: Scientific American-Sep. 1902	Image 52580 (132k, 1024x416) Photo by: Scientific American-Sep. 1902	Image 52581 (314k, 903x1024) Photo by: Scientific American-Sep. 1902 Location: 33rd Street	Image 52582 (222k, 1024x689) Photo by: Scientific American-Sep. 1902	Image 52583 (266k, 1146x1036) Photo by: Scientific American-Sep. 1902