A GIGANTIC BRIDGE.

Hauraki Plains Gazette, Volume XXXII, Issue 4319, 19 September 1921, Page 3

A GIGANTIC BRIDGE.

Some idea of the magnitude of the proposeu bridge over the Hudson Rivei’, oucvveeji xSew York uny and New Jersey, is conveyed in an article in the “Sicentific American.” The main outlines of the bridge, as at present determined', call for a total length from anchorade to anchorage of 6660 feet, divided into two shore spans each 1710 feet long, and a centran span across the river of 3240 feet. Including anchorages, the length is 7460 feet. The roadway, 220 feet in width, will be suspended from four steel chain cables, each consisting of 80 lines of eyebars, arranged in three banks and enclosed in a watertight tubular casting of bronze plating, whose diameter will be 15 feet. The upper deck will consist of a broad automobile and motor truck roadway 155 feet in the clear, and there will also be provision for two trolley line tracks and two 17 feet walks for passengers. On the lower deck will be ten trunk railroad tracks.

The function of a suspension bridge anchorage is to resist the horizontal pull of the cables. This, in the Hudson Riverbriidige, amounts to 260,000 tons. Resistance to this pull, with a wide margin to spare, is obtained by bulding the anchorage of such size and weight that the frictional resistance to movement between itself and the ground is sufficient to hold the ctables taunt, and do so with a sufficient friction in reserve to prevent the slightest movement. The engineers’ calculations call for a mass of masonry measuring on its base 400 feet in the direction of the length of the bridige, 375 feet in width and 220 feet in ‘height, while upon this base will stand two office buildings 70 feet in width, 250 feet in length and- 280 feet in height. Looking along the axis of the bridge there will be a space of 100 feet between the inner faces of these buildings. On the two anchorages there will thus be four modern office buildings, which will contribute considerably to the annual receipts from the bridge. ( In order to secure sufficient height to give the chain cables the proper curve oi’ cetenary and also to secure a well-balanced architectural effect, it was found necessary to carry the main towers up to a full 'finished height of 840 feet. Also, to secure sufficient breadth to give stability, it was necessary to make the base of the towers 2.00 feet in depth by 400 feet in width. From this base the towers rise with a very pleasing curve to the summit, where they measure 100 feet in length by 200 feet in width. Externally the towers are of granite, but this stone work is merely a covering for the internal, very massive and strongly braced' towers, which carry the load of the cables. At a height of 170 feet above the ground level the tower will be pierced by three arches—a central arch 150 feet wide and 100 feet highland two side arches, each ,30 feet in width. In the centre of the face of the tower will be a round arch window, 120 feet in width and 275 feet in height. Its frame work will be of steel, and it will be filled in with heavy wired glass. The purpose of the windows,is to light the inferior, also, of course, they add to the architectural effect by breaking up the vast blank front of the tower. The total weight of steel in each towel’ will be 35,000 tons. On an equal scale of magnitude with the rest of this great structure is the double deck, suspended floor of the bridge. On tife upper deck on the extreme outside will be two 17-foot passenger footways. Adjoining these will be two tracks for trolley cars. Between the cables will be found one of the greatest boulevards in the world—a clear, unobstructed roadway, 155 feet in width and 12,000 feet in length. The anchorage will be pierced by three arches, one central arch 150 feet wide by 100 feet higl-, and two 30-foot side arches. The roadway will be covered with asphalted concrete.

It will be absolutely watertight, and its broad surface will give ample room for sixteen automobiles and motor trucks to pass abreast across the bridge if a rush of traffic made this necessary. On the lower deck will be ten railway tracks, over which will pass the transcontinental trains of all the roalroads that come into Jersey City from the west, and also such freight trains as are destined for Manhattan, the Bronx and Long Island.