THE GREAT EAT BRIDGE

Hokitika Guardian, 7 September 1921, Page 3

THE GREAT EAT BRIDGE

NEW YORK’S VAST STRUCTURE TOWERS ABOVE WOOLWORTH BUILDING. The greatest bridge in the world will lie- the- new one over the Hudson River. New York. It will cost about lit) million dollars, and as a. spectacle it will outshine practically every other human construction. It was not idealism or any striving alter tin- spectacular that le'd to the conception of tills bridge' upon such a gigantic scale. On the contrary, it* dimensions have been determined by the severest: application of tin- principles of economy, since in all const met ive- engineering work it has he-.-u prove d, partie ularly in recent v,.:ers. that there is economy in e-oneen-ti-ilinn. It is because of iiie redo :ion both of the lirsi cost and of the enst of opi-i etion. which will lie secured by carrying the transportation between (he Western continent- and Manhattan Island on a single bridge, fliat the Hudson River structure has lieou planned upon its present stupendous si i.lo.

The mail! outlines of the bridge-, as at prose-nt determini-d,- says the Bcien-lifie-Aiiii-rican. call for a total h ilgtli from aiie-hurage- of litlbff feci, divifle-d into two shore spans oae-li 1710 feet lung, and a e-cntral span across tin-i-iv.-r of 32 111 fi'.-t. I minding anehnr- ||„. lengrii is 7-llit) fee-l. The roadway. 220 t.-e-l in willth. will he sus-pe-n-ele-el from four steel chain cables, ene-h consisting of 30 lines of eyebnis arranged in three banks and enclosed , in a watertight tubular easing of j bronze plating, whose- diameter will be j 1 feet. The upiier deck will consist j ~(• I, broad automobile and motor- i (ruck roadway 100 feet in the cleai. and there will also be provision for two | trolley line tracks and two 17-foot- | walks for passengers. On the lower | dee k will be ten trunk railway trae-ks. i THE ANCHOR AGES. | There are four great steel and ma- J soni v structures to support the sits- j pension e-ahles wdiieh e-arrv the- dee-k. . The shore at- the eiiels are tile- ane-bor- j ages, with twenty minutes’ walk between them.

Tin- function of a suspension bridgeanchorage is to resist file- Horizontal pull of tin- cables. Tliis. in the Hudson River Bridge, amounts to 2(30.000 tons. Resistance- to this pull, with ft \\-jde- margin to span-, is obtained by building tin- anchorage of siie-li size and weight that, the frictional re'sistanec to movi-nn-nt between itsolt ami the- ground is sufficient to bold the ruble's taunt, aml do so with a suffie i.-nt friction in reserve to previ-nt- tin-

slightest- nuiveuni-nt. Tin- oiigini-ms e eli-übitioii* call fe'i- a mass of masonry measuring oil its base lot! fe-e-t in tlu* ellii-ition of the li'-ngth of the liriilge, 37-** le-ct in wieltli. anel 220 Dot in bri-dit. wtiile* linnn this base' will stand tell- i ) ‘l* ee ■ hllileliugs 711 t-'e-t ill ‘evldlii. 2.M1 I'l-e-t in leiealh. anil 280 feet in he-igbt. l-iiokintr along the axis of the-

bridge-, there- will la- a spa*-*- ol 100 t'e-.-t between tin- inner fae-es of these hi-ildings. On the two amhovages ol these will tints In- four modern office buildings, which will e-ontribute enn-siele-rablv to the- annual receipts from I he- hrielge. TILE MAIN TOWERS.

In order to secure sufficient height to .jive tin- ell .in cables the proper curve 1.1 catenary and also to secure a wrll'•alan.ed architectural effect, it was f 11 ml necessary to carry the main towers up to a full finished height of 810 I'.et. Also, to secure sufficient '.readtli to give stability, it was necessary to make the base of the towers 200 feet ill depth by -KMI feet in width. From this base the towers rise will, a very 1 leasing curve to the summit, where these measure 100 feet in length by -j: )|I feet ill width, ft. should Ik- understood that the structural part of the towers, which carries the load of the .aides, is not, visible. Externally the towers are of granite; hut. this stonewink is merely a covering for the it'tcrmil very massive, and strongly-hr need steel towers, w hich carry the load of !he cables. The external masonry walls were adopted, partly for their architectural effect, and principally to act as a protection for tile internal steel work. This protection will h** so complete that one painting of the towers wih he go al for a period of at. least a decade. -

At a height of I7l> feet above ground level, the tower will he pierced by three arches, a central arch lot) feet wiilc and litO feet. high, and two side arches each MU feet in width. In t lie centre of the face of the. tower will he a round arch window 120 feet in width and 27d feet in height. Its framework w ill I.e of steel, and it', will he filled in with heavy wired glass. The purpose of the windows is to light the interior; also, of course, they add to the architectural effect hv breaking up the vast blank front of tin* tower. the total weight of steel in each tower will |,c an,ooo toils. Those towers will actually overtop the highest ot Now York's skyscrapers, the famous Woolworth Huildings by 18 feet, and their bases are roughly three times as wide as the Wonlworth block. THE FLOOR OF THE RRTDOE. Oil ail equal settle, ol magnitude w ith t-ho rast of this great, structure is the double-deck, suspended floor of the bridge. Oil the upper (leek, on tile extreme outside, will he two 17-foot |Stssenger footways. Adjoining these will Is' two tracks lor tram ears. Between tile cables will Is- found one of the circa tetht boulevards in the world a clear, unobstructed roadway looleet 111 width and 12.1X10 feet in length, including the approaches. Entrance to this roadway commences near Ninth-avenue New York. The anchorage will be pierced bv three arches, one contra] arch I r,(j feet wide hv 100 feet high, and two 30-font side aridies. The roadway will f,e covered with asphalted concrete. ! will l,e absolutely watertight, and its broad surface will give ample room for sixteen automobiles and motor-trucks to pass, abreast across the bridge, if a msh of traffic made this necessary. On the lower deck will be- ten railway tracks over which will pass the transcontinental trains of all the railroads that come into Jersey City from the west, and also such freight trains 11s are destined for Aranliattnn, the Bronx and Long Island.

t a WEATHER-PROOF RRTDnF. i .V new and buddy important feature

introduced for the first time in a bridge of this great magnitude is that practically the whole of the Hudson River Bridge will be weather-proof. That is to say, its steel work will be so completely enclosed with rain-and-moisturc-exeluding material that the annual cost of repainting—a most serious item in the upkeep of a big bridge—will he so protected. The upper deck of the br'idge being water-tight, it follows that the whole of the steel work below it,, including the lloorbeams, girders, tracks, etc., will he similarly protected. Eat-b chain cable as above stated will be enclosed in a continuous wnter-tigl ! tube or easing of bronze which will '-liable tli o . bridge crew to make periodical inspection of the cyeba-rs which compose the cables. The result of flic weather-proofing is that only 15 per cent of t-lie steel work will he exposed. Were it not for the protective feature the annual hill for painting the scores of acres of surface of the bridge woillel amount to at least- half a million dollars. Because' of the weather-proofing the annual cost for painting will be but a fraction of this sum

\s may well be imagined, the weight of tin- steel in a bridge of these proportions runs up to a very high figure. Tin' Olympic, tlio Leviathan, and Aquitanin could lie placed on the floor of the main span and still 1.-avo some 10” feet- to spare. Still more remarkable is the fact that- tin- combined weight of these throe vessel* when loaded, which is about 1(10.000 tons, would fall far short of tlic unloaded weight- of the main span of tlic bridge.