SCIENTIFIC AMERICAN — April 28, 1894

This Article and 2 Illustrations come from a time when The Bronx, NY was not consolidated into the City of New York.
Mott Haven lies in The Bronx but was known then as part of the Annexed District.

THE PARK AVENUE IMPROVEMENT IN NEW YORK CITY.

The Grand Central Depot, at the corner of Fourth Avenue and Forty-second Street, in this city, is the main railway terminus on Manhattan Island, it is reached by four tracks on the line of Fourth Avenue, running south from the Harlem River, The tracks start from the street level at the Grand Central Depot, the entire region about the depot being given up to the track yard, round-houses and other structures appertaining to the railroad service. A few blocks above Forty-second Street the streets crossing Fourth Avenue are provided with bridges, but for a space of several blocks Fourth Avenue cannot be crossed. At about Forty-ninth Street the tracks begin to be depressed, and up to Ninety-eighth Street they run virtually in a tunnel, over two miles long. This leaves the street above unencumbered. The avenue is 140 feet wide, and through its center and above the tunnel are a series of little parks, whence the name of Park Avenue has been given to it. Trains passing through the tunnel have an unobstructed track and do not reach the ground level until they get to Ninety-eighth Street, Here the street grade falls rapidly and the car tracks are carried on an elevated viaduct of stone and earth filling. At 106th Street the work of the Park Avenue Improvement Commission begins. It consists in making connections to and in building a four-track elevated steel viaduct from 110th Street to Mott Haven, where the tracks gradually run down to the depressed road in the annexed district. The general aspect of the finished structure is shown in Fig. 3.

The way is carried on three rows of lattice steel columns, each row supporting plate girders. The intermediate cross trussing is provided by the flooring, besides which there is a transverse lattice girder for each set of columns. This is arranged on the solid floor system, now in extensive use by the New York Central Road on its bridges. A cross section of it is shown in Fig. 6. It virtually consists of a series of three-sided box girders built up of steel plates and angle irons. The plates are three-eighths inch thickness, and the depth of the vertical plates averages 18 inches with a width of 14 inches. The channels thus formed are open alternately above and below, and cover the entire area with a water-tight floor. From center to center of cross space the distance bridged by the girder floor is 28 feet, giving a total width of floor of 56 feet, a plate girder running along each side and one through the center. The girders are 7 feet 2 inches deep, and the webs are of three-eighths steel for the side and 9-16 for the center girders. From center to center of columns is 65 feet.

The street beneath the viaduct will be graded and paved, and is to be thrown open to the public, leaving the full width, 140 feet between house lines, open and unobstructed, except by the three rows of columns. The Harlem River is to be crossed on a four-track high level bridge, with a center pier drawbridge. Immediately across the river Mott Haven is entered, and here an elevated level station is to be built. The Harlem River bridge is shown in Fig. 4, the Mott Haven station in Fig. 1.

One of the purposes in carrying out the improvement is to free the street from the encumbrance presented by the stone viaduct and to do away with bridges at street crossings. This is an object of such importance as to justify the city in paying a part of the expense. The use of an elevated bridge over the Harlem River is also one of the most important features of the work. The river in question is a legal waterway open to navigation. A low drawbridge, such as in use at the present time, is not only an obstacle to vessels, but the necessity for its periodical opening has interfered with the running of the trains. The new bridge is to be so high that the majority of vessels using the Harlem River can pass under it. Thus, while it can be opened, it will be rarely that the necessity for doing so will arise. The bridge, by its high level, will at once improve the conditions of railroad and river traffic.

The system of carrying out the work without disturbance of traffic remains to be described. In Fig. 5 is given a view of the work of erection looking north from 107th Street. Here the operations include removal of the viaduct now carrying the roadbed and its replacement by the new structure. Temporary wooden trestle work is to be built on each side of the present viaduct and on this the trains are to run reaching the grade of the old road at about 115th Street. This leaves the ground clear for the demolishing of the old and erection of the new viaduct. When 115th Street is reached, where the tracks begin for part of their extent to be depressed, another system is adopted. The side columns are put in place, as shown in Figs. 6 and 7. But the tracks being all occupied, it is impossible to put in the center columns. Accordingly wooden trusses are to be thrown across from the lines of the side columns, and resting on the old retaining wall, and these trusses provide a center bearing for the center longitudinal girder. In this way, as also shown in Figs. 6 and 7, the full permanent flooring is sustained by side columns and temporary transverse trusses. The trains at this stage can run over the new tracks, definitely abandoning the old. This leaves the ground clear for work. The center piers will now be built, the columns will be erected on them, and after the columns are in place the wooden trusses will be removed.

This procedure it will be observed is adopted to keep four tracks in use. But the temporary Harlem bridge will be a two-track structure. For a short distance below it, therefore, the four tracks are merged into two lateral ones, as shown In Fig. 2. This leaves the scene unobstructed, and the viaduct can be built at this place without any special methods of construction.

The sequence of the improvement provides, as said, for a four-track elevated level bridge over the Harlem River. This in itself will be an innovation, and will be the only four-track bridge of this description in the world. To enable it to be built without interruption of traffic, a temporary viaduct with a draw-opening has been erected to the westward. The tracks will pass over this structure while the main bridge is being erected. The temporary draw of the hinged type, swung from horizontal to vertical position when opened, is quite peculiar, and in itself is an object of interest. It was about a year ago moved bodily from its position on the line of the old bridge to its new location to the west. We illustrated in the SCIENTIFIC AMERICAN of December 31, 1892, this operation, one of remarkable interest, as being performed without interruption of traffic, The same illustration may be referred to as showing the old and new lines of road, the one where the new bridge is to go, the latter for temporary use during the improvement.

In Fig. 8 we show the relations of the old to the new. The locomotive is on the old tracks. Along the line are seen the side columns, whose bases are on the street grade, and the side girders, marking the viaduct bed, are seen resting on the columns.

The trussed flooring is to be riveted by means of angle clips to the longitudinal central and side plate girders, The rails are to be clipped to the flooring without sleepers, sound-insulating or deafening pads being placed beneath them.

The steel structure is supplied by the Elmira Bridge Company and the New Jersey Iron and Steel Company at a contract price of $1,500,000. The masonry work of the piers, it is estimated, will cost $100,000; the temporary work, $100,000; the Harlem pier bridge, $1,000,000, and the work at Mott Haven. $500,000. This aggregates over $3,000,000, of which amount the city of New York is to pay $750,000.

The work is in the hands of a special commission appointed by the Mayor, under a special act of the Legislature. It is entitled the Board for the Park Avenue Improvement above 106th Street, and includes the following members: John Fox, president; James H. Haslin, secretary; Walter Katte, superintending engineer; Almerin H. Lighthall, Peter F. Meyer.