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TowerBridge•TowerBridge,whichwasbuiltfrom1886to1894,isacombinedbasculeandsuspensionbridgeinLondon,overtheRiverThames.•ItisclosetotheTowerofLondon,fromwhichittakesitsname.IthasbecomeaniconicsymbolofLondon.TheHistoryofTowerBridgePlansfortheTowerBridgeweredevisedaround1876whentheeastofLondonbecameextremelycrowdedandabridgeacrosstheThamesinthatareaofthecityseemedanecessity.•Itwouldtakeanothereightyears-andlotsofdiscussionsaboutthedesign-beforeconstructionofthebridgestarted.•Thebridge,designedbycityarchitectHoraceJonesincollaborationwithJohnWolfeBarry,wouldeventuallybecompletedin1894.Atthetimemanypeopledislikeditsdesign,butovertimethebridgebecameoneofLondon'smostfamoussymbols.TheTowerbridgewasopenedbyKingEdwardVII.Thebridgewasconstructedintheyear1894.•Thebridgestandsataheightof60metersandtheheightofeachtowerisabout43meters.Themiddlepartofthebridgecanbeliftedupwhenhugeshipspassthrough.Construction•Constructionwasstartedin1886.Theprojecttookeightyears,involvingfivemajorcontractorsand432constructionworkers.•Twomassivepiers,containingover70,000tonsofconcrete,weresunkintotheriverbedtosupporttheconstruction.Over11,000tonsofsteelprovidedtheframeworkforthetowersandwalkways.Thiscanprotecttheunderlyingsteelworkandtogivethebridgeapleasingappearance.In1894,thebridgewasalandmarkfeatofengineering,combiningelementsofasuspensionandhighlevelbridgeandabascule.Thisbridgehas269m(882.5ft)length,32m(105.0ft)width,104m(341.2ft)longestspan.BeautifulstructureMechanicsTheproximityoftheharboranditslocationinthedirectionofthesearequiredthebridgetoallowthepassageoflargevessels.•Themechanismtoopenthebridgeishiddeninthetwotowers.Until1976,whenthemechanismbecameelectrified,steampowerwasusedtopumpwaterintohydraulicaccumulatorswhichpoweredtheengines.Howdoesitwork?CloseOpenDesign•Thetowersissplitintotwoequalbasculesorleaves,whichcanberaisedtoanangleof86degreestoallowrivertraffictopass.Thebascules,weighingover1,000tonseach,arecounterbalancedtominimizetheforcerequiredandallowraisinginfiveminutes.•Thetwoside-spansaresuspensionbridges,each270feetlong,withthesuspensionrodsanchoredbothattheabutments.Thepedestrianwalkwaysare143feetabovetheriverathightide.•Eachdeckismorethan30meterswideandcanbeopenedtoanangleof86degrees.Whenopenedthebridgehasaclearanceofalmost45meters.Itusedtoopenalmost50timesadaybutnowadaysitisonlyraisedabout1,000timesayear.TheinsidestructureofTowerBridgeItsstairsremainthestyleof18thcentury.Goingthroughtheseantiquestairs,youcanarriveattheupperpartoftheTowerBridge.AndyouwillfeelrichhistoricalcultureofLondon.TheTopoftheTowerTocommemoratethebuildersofthetower,therearesomespecialstatuesinthetopofthetower.Peoplecanimaginethescenethatworkersworkedhardandseriouslyinordertofinishtheproject.FacilitiesinsidethetowerEveryday,thesemachinesensuretheoperationofthebridge.Ithasrunformorethanonehundredyears.InterestingFactsofTowerBridgeThebridgefeaturedinpublicityforthe2012SummerOlympicsbeingheldinLondon.InJune2012，asetofOlympicringswassuspendedfromthebridgetomarkonemonthtogountilthestartofthegames.Theringscostalmost£260,000tomake,measured25by11.5metresandweighed13tonnes.1977-TowerBridgewaspaintedred,whiteandbluetocelebratetheQueen'sSilverJubilee.(Beforethat,itwaspaintedachocolatebrowncolour).In1952,aLondonbusdrivenbyAlbertGuntonhadtoleapfromonebasculetotheotherwhenthebridgebegantorisewiththebusstillonit.In1912,duringanemergency,FrankMcCleanhadtoflybetweenthebasculesandthehigh-levelwalkwaysinhisShortbiplane,toavoidanaccident.Whenthegiant50ft-tallrubberducksaileduptheThames,itwentthroughtheTowerBridge.Becauseitistoohuge,theTowerBridgeopenedforit.Ithasalreadyvisitedfamouswatersaroundtheworld.