Collections Item Detail

2012.007

Lukacs, Claire

Gift

Museum Collections. Gift of a Friend of the Museum.

1891 - 1891

Date(s) Created: 1891 Date(s): 1891

Notes: Archives 2012.007.0118 ==== Scientific American A WEEKLY JOURNAL OF PRACTICAL INFORMATION, ART, SCIENCE, MECHANICS, CHEMISTRY, AND MANUFACTURES. Vol. LXIV.- NO. 21. [Entered at the Post Office of New York, N. Y. as Second Class Matter. Copyrighted, 1891, by Munn & Co.] Established 1845. NEW YORK, MAY 23, 1891. $3.00 A YEAR. ---- THE PROPOSED HUDSON RIVER SUSPENSION BRIDGE. Nearly a year has elapsed since we illustrated the proposed bridge across the Hudson River, to be constructed from designs by Mr. Gustav Lindenthal, of Pittsburg, Pa. At that period the bill authorizing the construction of the bridge had passed the House of Representatives, and was awaiting action by the Senate. The bill has now passed both Houses, has been signed by the President, and is law. Under it the question of the height is left to the discretion of the Secretary of War, provided a minimum height equal to that of the East River bridge be obtained. This question was delegated by the Secretary of War to the Board of Army Engineers, sitting in New York City, and plans have been just approved by the Secretary of War and the height fixed at 150 feet above high water. The plan of the bridge has been modified in several respects, and we give a perspective view of the proposed structure. It will comprise five divisions : a central span, two land spans, and two approaches. The bridge proper will start from the New Jersey anchorage, abutting on the northwest corner of Bloomfield and Twelfth Streets, Hoboken, and on the New York side will terminate at its anchorage on the northeast corner of Twenty-third Street and Tenth Avenue. The distance between these points, as far as ascertained, is 6,650 feet. The central span will be 3,100 feet from center to center of piers, and the shore spans will be 1,750 feet each, measured as above. The clear span of the central bay is to be 2,920 feet. At the point selected for the bridge there is a space of 2,740 feet between the pier head lines as established by law. Both piers couie inside of this line, so that the legal channel of the river is not to be interfered with. The structure is to be of steel for the roadway and towers, while stone and concrete (beton) will be used in the anchorage and foundations. These foundations it is proposed to establish upon the solid rock. Double steel towers 525 feet high, on foundations 180 by 350 feet, will carry the cables, which will pass over balancing saddles. The cables, four in number, are to be arranged in pairs, one nearly vertically over the other, and of 48 to 50 inches diameter each, The cables are 55 feet apart vertically. To prevent deformation and to cause the cables to act to a certain extent as truss chords, diagonal braces are inserted between the members of each pair of cables. The whole thus constitutes two arched trusses, which will resist deformation from strains to considerable extent. The cables are to be made of steel wire, laid parallel, and bound together at intervals ; but they are not to be bound with wire, as in the East River bridge, but are to be surrounded by a cylindrical sheet steel casing bolted on. This casing is to be water tight, and of such size as to provide two inches of space all around the cable for the circulation of air and for the equalizing of temperature. It has been found that in this gigantic structure uneven heating of the wire cable^would produce undesirable strain, and the covering of the cables will to some extent counteract this. The planes of the cable are inclined about eight per cent from the vertical, in order to give stiffness to the structure. With extreme ranges of temperature, it is calculated that the center of the cables will rise and fall through a range of nine feet. Thus in cold weather the height of the bridge at its center may exceed by feet its normal height. Two anchor columns are placed at intermediate points between the anchorage pedestals and the main towers. These are entirely below the roadway and carry no dead weight, but come into action in cases of unequal loading. The maximum load to be allowed is only equal to one-quarter the ultimate strength. As live loads in the calculations, for each of the main tracks a 1,000 foot 1,200 ton train was assumed, and for the rapid transit tracks a 300 foot 200 ton train each, while for the promenade 13,000 men were assumed. All this weight was supposed to be placed upon a single span, with the result of indicating the large factor of safety expressed above. With 1,330 locomotives loading the bridge from end to end, only one-third its ultimate strength will be called upon. The dead weight of the structure will be nearly three and one-half times this amount. The suspended framework is to be made as rigid as possible. (Continued on page 323.) ---- [caption center illustration] DOUBLE CABLE ANCHORAGE AND ANCHORAGE PLATES. ---- [caption bottom illustration] THE PROPOSED HUDSON RIVER SUSPENSION BRIDGE, CONNECTING NEW YORK AND HOBOKEN. ==== Page 323, column 1 THE PROPOSED HUDSON RIVER SUSPENSION BRIDGE. (Continued from first page.) It comprises trusses, also of 55 feet height, to accommodate the decks. A wind pressure of 50 pounds to the square foot has been assumed as a basis for the calculations, and to resist it two horizontal trusses, 115 feet deep, extending continuously from anchorage to anchorage, are provid ed. This represents the space afforded for the decks, which are of this total width, being a few feet less in the clear. Of these decks there are to be three, although it is designed to construct only one of them at present. The lower one is to carry for the present six and ultimately eight tracks for regular railroad service. On the second deck there are to be four rapid transit tracks and there is room for two additional heavy service tracks. The third deck is to afford a promenade twenty feet wide. It seems a pity not to arrange a roadway for carriages, as it would afford a most impressive drive, but the approaches for such roadway from the low ground on either shore are considered impracticable, and the ferries are relied upon as more convenient for wagon traffic. As regards the question of height, this is limited by the necessity of preserving a proper grade. At the height of 135 feet, as originally proposed, at 60° F. the grade upon the Ne w York side is 1.9 per cent, or 95 feet to the mile, and on the New Jersey side 1.4 per cent. The heavier grade is more than is desirable. The middle span, in order to keep the grade low, is restricted to a rise or camber of not more than 19 feet. Shipping will be to some extent inconvenienced by the lower height, but it is stated that last year only seventeen ships lowered their upper masts to pass under the Brooklyn Bridge. The New York station is to be in the neighborhood of Sixth Avenue, above Twenty-third Street. It is to be 1,300 feet long, and is to include a 400 foot loop for drilling trains. The approaches to the anchorage will be largely of stone and brick. On the New Jersey side the approach will extend across Bergen Hill through an open cutting. At the two anchorages passenger elevators will be provided, giving access to the foot promenade. The future work of the bridge is based upon the present traffic from the New Jersey shore. Daily, over 150 express and 680 local trains arrive at and depart from this locality. The Hudson River ferries carry now fifty-two million passengers annually, and it is believed that thirty millions of these would use the bridge during the first year of its existence. It must be remembered that it may take ten years to complete it, and that the traffic will be increasing meanwhile. Again, as regards its capacity, it is found that the New York elevated railroads carry one hundred and eighty millions of passengers annually on eight tracks, and the Brooklyn Bridge carries thirty millions on two tracks. There is to be no restriction on speed on the Hudson River Bridge, so that its capacity pro rata will be still greater. The government and direction of the company is vested, by the act of Congress authorizing the building of this bridge, in a board of seven directors. The president of the company is Mr. Jordan L. Mott, of New York, and the other directors are Edward F. C. Young, of Jersey City; Thos. F. Ryan, Charles J. Canda, and Wm. Brookfield, of New York; James Andrews, of Allegheny, Pa.; and J. K. McLanahan, of Hollidaysburg, Pa. [end of text] ---- [caption center illustration] SUGGESTED LOCATION OF BRIDGE ANCHORAGE STATION AND APPROACHES. ---- [caption bottom illustration] MAP OF NEW YORK CITY, SHOWING LOCATION OF HUDSON RIVER BRIDGE. Status: OK Status By: dw Status Date: 2013-04-04