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Progress of the New York Rapid Transit Tunnel (1901)

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Scientific American · January 19th, 1901 · pp. 37.

Progress Of The New York Rapid Transit Tunnel.

Work on some sections of the Rapid Transit tunnel is so advanced that it is now possible to get a good idea of the appearance of the inside of the tunnel as it will look when completed. The graphs were taken on Broadway at 135th Street, at the point where the long viaduct, by which the tracks will be carried across the Manhattan Valley, intersects the northern slope. The subway at this point has been built in an open excavation, and our illustrations were taken when the steel bents had been placed in position and before they had been walled in with a covering of concrete.

The whole of the subway and tunnel construction is to be of absolutely waterproof construction, and some description of this waterproofing and of the concrete filling will be of interest. The floor consists of a layer of concrete which varies in thickness, being 8 inches upon rock, and thicker when it is laid upon a loose or moist formation. Above the 8 inches of concrete is spread a layer of waterproof material, which is put down in the following manner: After the 8 inches of concrete has been carefully smoothed off, a layer of hot asphalt is spread upon it, and upon this is rolled down a sheeting of felt. Then follows another layer of asphalt and felt, the layers varying from two to six, according to the dampness and general characteristics of the surrounding material. Above the waterproofing is another layer of concrete, in which are laid the tracks and the stone or concrete footings for the columns and I-beams which support the roof and sides of the tunnel. The steel framework, as shown in the engraving, is made up of transverse bents, consisting of built-up columns, spaced 5 feet apart longitudinally and 12 feet 6 inches apart measured in the direction of the tunnel. The top member of each bent is a heavy I-beam. The wall posts also consist of I-beams, and angle iron knee-braces are riveted at the upper angles formed by the junction of the center and side columns with the roof to give lateral stiffness to the whole framework. The spaces between the I-beams of both the wall and the roof are filled in with concrete, which is smoothed off flush with the outer flanges of the metal. Immediately upon the flanges and the outer surfaces of the concrete filling as thus finished off is placed a complete layer of asphalt and felt waterproofing similar to that used in the floor as above described. After the felt has been put in place an outer layer of concrete whose thickness is determined by the nature of the excavation is carefully rammed in place. The subway as thus finished is inclosed in a waterproof envelope, which extends entirely around it.

The two interior views of the subway which we present are taken at the point where the masonry viaduct which forms the abutment of the steel viaduct across Manhattan Valley commences. This viaduct, which will be located about a thousand feet east of the Riverside Drive viaduct, will consist generally of plate girders carried upon braced towers, except across Manhattan Street, which will be spanned by a single elliptical arch of handsome design.

The engineers and the majority of the contractors of the Rapid Transit Commission are to be congratulated upon the progress which is being made. With a few exceptions, such as the section along Forty-second Street, the work has been opened up from Duane Street to 181st Street on every mile of the route, and for long stretches the excavation is practically continuous. In several sections the steelwork is in course of erection, and the concreting is keeping pace with it. The two deep shafts at 167th and 181st Streets are down to grade, and the drifts are being pushed forward. Steel is on the ground in sufficient quantities to keep the erecting gangs busy; and altogether the prospects of completing the tunnel on contract time are promising.

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Scientific American · May 25th, 1901 · pp. 327.

Some Features Of The New York Rapid Transit Tunnel.

It is questionable whether the citizens of New York appreciate what a truly splendid system of transportation will be at their command when the Rapid Transit Tunnel is put in operation. The new system will not merely add four new lines of track to the already large number of north and south lines which extend the full length of Manhattan Island, but it will provide a service of express trains which, in point of frequency and speed, will be positively without a rival. This is a fact that is not by any means realized, and when the road is opened it is going to come as a most agreeable surprise to the traveling public.

From the very first it has been the policy of the engineers of the road to make it a sine qua non, that the rapid transit road must be essentially a high-speed system, which will not merely possess an enormous carrying capacity, but will also transport passengers at a speed that has never been approached by any other road on the island. From the present terminus at City Hall Park, express trains are to be dispatched during the rush hours at two minutes' intervals. They will make stops at Fourteenth, Forty-second, Seventy-second, Ninety-sixth Streets, and the whole run to One Hundred and Fifty-seventh Street will be made in 16.5 minutes. The fastest traveling at present provided for the public is by the express trains on the Ninth Avenue Elevated Railroad, on which the run, by actual timing, from Franklin Street to One Hundred and Thirty-fifth Street is made in about half an hour, the time between the same points by the local trains being forty minutes. The average running speed of the Rapid Transit express trains, including stops, will be 38 miles per hour; and this means that, at times, the speed will rise to 50 miles an hour, and occasionally over that. The local trains will have an average speed of 18 miles per hour, which is about 50 per cent greater than that of the present local trains on the Manhattan elevated roads. The express stations will be located at intervals of a little less than 2 miles, while the local stations will average about four to the mile. At one time the question of increasing the number of express stations was mooted; but the Rapid Transit Commission, by advice of its engineers, wisely decided that, since the system was to provide, primarily, an express service, it would defeat the end in view to multiply the stops. It was further urged that the high speed of 18 miles per hour of the local service rendered it unnecessary to multiply the express stations, the passenger being able to quickly cover the distance between the express stations and his own particular stopping-place, by the fast local service. That an average speed of 18 miles per hour can be maintained with stations only a quarter of a mile apart is due to the rapid acceleration which is possible by electric traction, and also to the fact that the local stations are placed a few feet above the average grade of the line-an arrangement under which gravity assists the retardation of the train in approaching the station, and increases the acceleration when the train is running down hill at starting.

Since the opening of spring weather, progress all along the line of the tunnel has been quite rapid, and the whole system presents, from end to end, a very animated appearance. There is much work now being done, moreover, of which but little evidence appears at the surface, particularly where the line runs in tunnel proper and the excavation is being carried out by drifting. Our lower front-page illustration shows one of several stretches of work of this character. The sectional view is taken at the intersection of Thirty-fourth Street and Park Avenue, at the entrance of the tunnel which is now used by the electrical cars of the Metropolitan Street Railway system. That portion of the underground road which lies south of the entrance to the tunnel is contained in one four-track subway as shown in the sectional view at the top of the page. Shortly before Thirty-fourth Street is reached, the four tracks diverge somewhat, and are carried in pairs through two separate tunnels which are located beneath and somewhat to the right and left of the old surface tunnel. This arrangement is shown in our sectional view, which is taken at the point where the Thirty-fourth Street station will be located. It will be noticed that the two tracks of each tunnel are at different elevations, the outer or local tracks being 4 feet higher than the inner express tracks. This difference of level is due to the fact that Thirty-fourth Street is not an express station, and the express tracks are therefore carried through at the normal grade of the line, the local tracks being carried at a few feet higher elevation, according to the method employed at local stations, as already explained. The Park Avenue tunnel is one of the sections of the road where there is far more work being done than appears at the surface, Two shafts have. been sunk immediately to the south of the portal wall of the old tunnel to a depth of 48 feet below the Thirty-fourth Street level, and from the bottom of each 3haft the tunnel is being excavated north and south by as large a force of men as can be worked to advantage against the face of the rock. As the tunnel is completed, it is lined with concrete, the track system being sunk in the floor and the roof turned with an elliptical arch, as shown in our drawing. At Thirty-fourth Street, the roof of the Rapid Transit tunnel is so near to the base of the Fourth Avenue tunnel that the concrete has been carried up to a junction with the footing of the tunnel, as shown in the drawing. Elsewhere on Park Avenue the vertical distance between the tunnels is greater, and solid rock intervenes between the foundation of the old and the roof of the new tunnel. On Thirty-fourth Street there are two lines of track belonging to the Metropolitan Street Railway Company which are operated by means of storage battery cars, and it is an interesting fact that our sectional view presents at this point no less than eight tracks on which are used three different systems of electric propulsion-storage batteries on Thirty-fourth Street, the underground trolley in the old Fourth Avenue tunnel, and the third-rail system of the Rapid Transit tunnel. In our drawing also there are shown some of the electric cabs which are becoming an important element in city transportation, so that this particular drawing may be regarded as a sort of pictorial symposium of up-to-date methods of travel.

The construction of the underground tunnel road offers a great opportunity for solving the difficult problem of properly disposing of the water, gas, electric and other mains, which at present are buried in any sort of fashion beneath the streets, and are the source of untold expense and inconvenience whenever it becomes necessary to renew or repair them. It is a pitiful commentary upon our supposed twentieth century development that these mains should be buried beneath the streets in the altogether haphazard fashion which is shown in the small sketch on our first page, which represents the condition of things at the intersection of Nineteenth Street and Fourth Avenue. It was the intention of the Rapid Transit Engineers to provide special galleries on each side of the subway, and locate the water and gas and other mains within them. Provision was made for these galleries wherever it was possible to use them, and steel was ordered and considerable excavation done in Elm Street, at a cost of about $35,000. The galleries were abandoned, however, because of opposition encountered from the heads of the Sewer, Water and Gas Departments, who raised various objections of a more or less trifling nature. The Rapid Transit Commission, considering that it was its duty to build the tunnel rather than press the question of the pipe galleries to the point of becoming involved in legal complications and delays, decided to leave the question open for future consideration. While we do not dispute the wisdom of the policy pursued by the Commission, there is every argument to be used in favor of the construction of the pipe galleries simultaneously with the building of the tunnel. At present the pipes are merely suspended from falsework during the construction of the subway, and after a section is roofed the soil is filled in around the pipes, leaving them in the unsatisfactory condition which necessitates pulling up the roadway whenever repairs or changes are to be made.

We present a typical section of the tunnel as it was proposed to construct it, with the two galleries adjacent to the tunnel and separated from it by steel and concrete walls. The larger pipes, such as the water and gas mains, would be carried on the floor of the tunnel, while all other pipes, such as those for compressed air, steam, etc., might be suspended from the roof or carried on brackets extending from the side walls. The galleries would be entered by manholes, or other suitable means of communication. and pipes could be repaired, renewed or inspected without any disturbance of the surface of the street.


Sectional View at Thirty-fourth Street and Park Avenue, Showing Eight Tracks at Three Different Levels. [Inset at lower left:] Antiquated method of laying pipes at present adopted. View at 19th St. and Fourth Avenue.

Scientific American · May 25th, 1901 · pp. 322.

Pipe Galleries For The Rapid Transit Subway.

The construction of the rapid transit subway afforded an opportunity for making proper provision for the mass of electric cables and gas and water pipes, which lie beneath the streets of the city, and are the cause of endless annoyance in the way of excavations for repairs and relaying. The opportunity to build along one or both sides of the subway special galleries to contain these pipes appealed at once to the engineers in charge of the scheme. As we have shown elsewhere, plans were drawn up which made adequate provision for present and future needs, and $35,000 was spent in their construction. It is to be regretted that the pipe galleries have been abandoned, chiefly, it would seem, as the result of pressure of a semi-political nature brought to bear upon the Railroad Commission. The municipal engineers chiefly affected by the erection of pipe galleries have, for various reasons, so bitterly opposed their construction that, rather than entangle the whole tunnel contract with legal complications, the Commission has abandoned the galleries, at least for the present. We are of the opinion that the question of the construction of these galleries is second only in importance to the construction of the subway itself, and that it is absurd even to suggest that there are any insuperable difficulties in making adequate provision of this kind for the water pipes, gas pipes, electric cables and other lines which at present lie buried beneath our main thoroughfares. The present interruptions to traffic, the interminable and absolutely stupid way in which our choicest streets are dug up, relaid and dug up again, is a perpetual and obtrusive nuisance, which would not be tolerated in any provincial town, and cannot be too soon removed from the streets of the second greatest city in the world.


Typical section through the Subway, showing the Pipe Galleries as they should be constructed.

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