Lesson17Thelongestsuspensionbridgeintheworld

TheVerrazanoBridgeHowisthebridgesupported?Verrazano,anItalianaboutwhomlittleisknown,sailedintoNewYorkHarbourin1524andnameditAngoulême.Hedescribeditas‘a(chǎn)veryagreeablesituationlocatedwithintwosmallhillsinthemidstofwhichflowedagreatriver’.ThoughVerrazanoisbynomeansconsideredtobeagreatexplorer,

hisnamewillprobablyremainimmortal,foronNovember21st,1964,thelongestsuspensionbridgeintheworldwasnamedafterhim.TheVerrazanoBridge,whichwasdesignedbyOthmarAmmann,joinsBrooklyntoStatenIsland.Ithasaspanof4,260feet.

Thebridgeissolongthattheshapeoftheearthhadtobetakenintoaccountbyitsdesigner.Twogreattowerssupportfourhugecables.Thetowersarebuiltonimmenseunderwaterplatformsmadeofsteelandconcrete.Theplatformsextendtoadepthofover100feetunderthesea.Thesealonetooksixteenmonthstobuild.Abovethesurfaceofthewater,thetowersrisetoaheightofnearly700feet.Theysupportthecablesfromwhichthebridgehasbeensuspended.Eachofthefourcablescontains26,108lengthsofwire.Ithasbeenestimatedthatifthebridgewerepackedwithcars,itwouldstillonlybecarryingathirdofitstotalcapacity.However,sizeandstrengtharenottheonlyimportantthingsaboutthisbridge.’.

Despiteitsimmensity,itisbothsimpleandelegant,fulfillingitsdesigner'sdreamtocreate‘a(chǎn)nenormousobjectdrawnasfaintlyaspossible’.Topicsfordiscussion1Telluswhatyouknowaboutanygreatconstructioninthiscountry.2Tellusaboutfamousbridgesoftheworldyou