The知識資料Collapse知識資料of知識資料the知識資料Quebec知識資料City知識資料Bridge

朽木易折，金石可鏤。千里之行，始于足下。第頁/共頁TheCollapseoftheQuebecbyBruceRickettsIn1907Quebecwasbuildingthebiggestcantileverbridgeintheworld.

LittledidtheyknowthatonAugust29thattheywouldalsoexperienceoneofthelargestbridgecollapsesinhistory.ThebridgeacrosstheSt.LawrenceRiver,sixmileaboveQuebecCity,wasthebrainchildoftheQuebecBridgeCompany,agroupoflocalbusinesspeople.

UntilthengoodswerebroughtfromthesouthshoretoQuebecCitybyferry.

In1903theQBCgavethejobofdesigningofthebridgetothePheonixBridgeCompany.

TheyalsocontractedarenownedbridgebuilderfromNewYorkbythenameofTheodoreCoopertooverseetheengineeringdesignandconstruction.Thepeculiaritiesofthesitemadethedesignofthebridgeamostdifficultone.

BecausetheSt.Lawrencewasashippinglane,the2800footbridgemusthavean1800footsinglespan,almost150feetabovethewater,toallowtheocean-goingvesselstopass.

Further,thebridgewastobemultifunctionalandwasrequiredtobe67feetwidetoaccommodate2railwaytracks,twostreetcartracksandtworoadways.Forthosewhoarenotfamiliarwithacantileverbridgedesign,thinkofitasacontinuousbeamanchoredatbothendstopillars.

Thekeytothebridgedesignwastheweightofthecentrespan.

Thiscantileverdesignisalsouseinlargebuildingwhereinteriorpillarscannotbeusedtosupporttheroof,suchasaircrafthangers.Inlate1903,P.L.SzlapakaofthePheonixBridgeCompany,hadlaidouttheinitialdrawingsofthebridge.

HisdesignwasapprovedwithveryfewchangesbyCooper.

Theestimatedweightofthespanwascalculatedbasedontheseinitialdrawings.

In1905theworkingdrawingswerecompletedandthefirststeelgirderwasboltedintoplace.

TheseworkingdrawingstookoversevenmonthstoreachCooperforfinalapproval.

Inthemeantimetheworkhadbegun.

Itwasn'tuntilCooperreceivedthedrawingthathenoticedthattheestimatedweightofthespanwasoff,onthelowside,byalmost8millionpounds.

Cooperhadoneoftwochoices:condemnthedesignandstartover;ortakeariskthattherewouldbenoproblem.Tellinghimselfthatthe8millionpoundswaswithinengineeringtolerances,Cooperlettheworkcontinue.

Afterall,hewantedtobeknownasthedesignerofthegreatestbridgeintheworld.

AlsofactoredintothedecisionwasthatfactthePrinceofWales(latertobeKingGeorgeV)wasscheduledtoopenthebridgein1908andanydelayinconstructionwouldupsettheplanning.Hiswasafatefuldecision.OnJune15,1907aninspectingengineernotedthattwogirdersoftheanchorwasmisalignedbyaquarterofaninch.

Coopercalledthisa"notserious"problem.

IntheinspectionreportinAugust,1907,itwasnotedthatthegirdershadmovedoutalignmentabitmoreand"appearedbent".

Althoughthisconditionwasabitmoreconcerning,theworkcontinued.OnAugust27,1907thewarningbellsfinallywentoffwhentheinspectionteamheadedbyNormanMcLure,notedthat,overtheweekend,thegirdershadshifteda"coupleofinches"andweremoreobviouslybent.

TheengineersonsitedecidedtosendMcLuretoNewYorktoconsultdirectlywithCooper.

B.A.Yenser,aseniorengineeronsiteforPheonix,agreedthattheproblemwasseriousenoughtowarrantthetrip.

Therewasatelephoneattheconstructionsite,butphoningCooperwasdeemednotwisebecausethephonewasonapartylineandthewrongearsmightbelisteningin.

Andtheycertainlydidnotwanttoalarmanyone.Thenextmorning,withtheengineeringteamofftoNewYork,Yensertookituponhimselftocontinuework.

Whenaskedwhyherestartedtheworkconsideringtheconditionofthegirders,hestatedthathe"hadadream".

Inthedreamhewastoldthatthegirderproblemwasnotserious.

TheteamhadnotyetheardfromCooperbut

theotherseniorengineersonsite,forsomereason,agreedwithYenser.At5:32PMonthe29thofAugust,whileMcLurewasmakinghiswaybackfromNewYork,allhellbrokelooseattheconstructionsitewhenthegirderstrembledwithagrindingnoiseandgaveway.

Thebridgestructureplungedover150feettakingwithitthelivesof75