《土木工程专业英语 第2版》 课件 Unit7 Introduction to Other Branches；Unit8 The Greening of Engineered Cementitious Composites

EnglishforCivilEngineering——Teacher：Prof.ZhengLu（SchoolofCivilEngineering,TONGJIUNIVERSITY）Unit7IntroductiontoOtherBranchesofCivilEngineering

Unit7IntroductiontoOtherBranchesofCivilEngineering7.1BridgeEngineering（桥梁工程）

7.1.1ReinforcedConcreteGirderBridges（钢筋混凝土梁式桥）

7.1.2CableStayedBridges（斜拉桥）

7.1.3SuspensionBridge（悬索桥）7.2UndergroundEngineering（地下工程）7.2.1SeismicDesignandAnalysisofUndergroundStructure7.2.2PerformanceofUndergroundFacilitiesDuringSeismicEvents7.3TrafficEngineering（交通工程）7.3.1Introduction7.3.2TrafficManagementandControl7.4HydraulicEngineering（水利工程）7.4.1Introduction7.4.2TypesofHydraulicStructures7.1BridgeEngineering

7.1.1ReinforcedConcreteGirderBridgesTherawmaterialsofconcrete,consistingofwater,fineaggregate,coarseaggregate,andcement,canbefoundinmostareasoftheworldandcanbemixedtoformavarietyofstructuralshapes.Thegreatavailabilityandflexibilityofconcretematerialandreinforcingbarshavemadethereinforcedconcretebridgeaverycompetitivealternative.Reinforcedconcretebridgesmayconsistofprecastconcreteelements,whicharefabricatedataproductionplantandthentransportedforerectionatthejobsite,orcast-in-placeconcrete,whichisformedandcastdirectlyinitssettinglocation.钢筋混凝土梁式桥材料搭配与建造过程fineaggregate细骨料；coarseaggregate粗骨料；cement水泥；precastconcreteelements预制混凝土构件；fabricated制造；cast-in-place现场浇筑Cast-in-placeconcretestructuresareoftenconstructedmonolithicallyandcontinuously.Theyusuallyprovidearelativelylowmaintenancecostandbetterearthquake-resistanceperformance.Cast-in-placeconcretestructures,however,maynotbeagoodchoicewhentheprojectisonafast-trackconstructionscheduleorwhentheavailablefalseworkopeningclearanceislimited.Inthisunit,variousstructuraltypesanddesignconsiderationsforconventionalcast-in-place,reinforcedconcretehighwaygirderbridgearediscussed.钢筋混凝土梁式桥材料搭配与建造过程Monolithically整体地；maintenancecost维护费用；earthquake-resistanceperformance抗震性能；fast-track

快速；falsework

脚手架7.1BridgeEngineering

1SlabBridges（板桥）Longitudinallyreinforcedslabbridgeshavethesimplestsuperstructure

configurationandtheneatestappearance.Theygenerallyrequiremorereinforcingsteelandstructuralconcretethandogirder-typebridgesofthesamespan.However,thedesigndetailsandformworksareeasierandlessexpensive.Ithasbeenfoundeconomicalforsimplysupportedspansupto9mandforcontinuousspansupto12m.钢筋混凝土板桥Longitudinally纵向；superstructure

configuration上部结构形状；girder-typebridges梁式桥7.1BridgeEngineering

2T-BeamBridges（T形梁桥）TheT-beamconstructionconsistsofatransverselyreinforcedslabdeckwhichspansacrosstothelongitudinalsupportgirders.Theserequireamore-complicatedformwork,particularlyforskewedbridges,comparedtotheothersuperstructureforms.T-beambridgesaregenerallymoreeconomicalforspansof12to18m.Thegirderstemthicknessusuallyvariesfrom35to55cmandiscontrolledbytherequiredhorizontalspacingofthepositivemomentreinforcement.Optimumlateralspacingoflongitudinalgirdersistypicallybetween1.8and3.0mforaminimumcostofformworkandstructuralmaterials.However,whereverticalsupportsfortheformworkaredifficultandexpensive,girderspacingcanbeincreasedaccordingly.transverselyreinforcedslabdeck横向加筋板；formwork模板；skewedbridges斜交桥；

girder大梁；horizontalspacing水平间距；positivemoment正弯矩7.1BridgeEngineering

3Box-GirderBridges（箱梁桥）Box-girderbridgescontaintopdeck,verticalweb,andbottomslabandareoftenusedforspansof15to36mwithgirdersspacedat1.5timesthestructuredepth.Beyondthisrange,itisprobablymoreeconomicaltoconsideradifferenttypeofbridge,suchaspost-tensionedboxgirderorsteelgirdersuperstructure.Thisisbecauseofthemassiveincreaseinvolumeandmaterials.TheycanbeviewedasT-beamstructuresforbothpositiveandnegativemoments.Thehightorsionalstrengthoftheboxgirdermakesitparticularlysuitableforsharpcurvealignment,skewedpiersandabutments,superelevation,andtransitionssuchasinterchangerampstructures.topdeck顶面板；web腹板；post-tensioned后张法；torsionalstrength抗扭强度；skewedpiersandabutments倾斜支柱和台墩；interchangeramp立交匝道7.1BridgeEngineering

7.1.2CableStayedBridgesTheuseofinclinedstaysasatensionsupporttoabridgedeckwasawell-knownconceptinthenineteenthcenturyandtherearemanyexamples,particularlyusingtheinclinedstayasaddedstiffnesstotheprimarydrapedcablesofthesuspensionbridge.Unfortunately,atthistime,theconceptwasnotwellunderstood.Asitwasnotpossibletotensionthestaystheywouldbecomeslackundervariousloadconditions.Thestructuresoftenhadinadequateresistancetowind-inducedoscillations.Therewereseveralnotablecollapsesofsuchbridges,forexamplethebridgeovertheTweedRiveratDryburgh(Drewry,1832),builtin1817,andcollapsedin1818duringagaleonlysixmonthsafterconstructionwascompleted.AsaresulttheuseofthestayconceptwasabandonedinEngland.Nevertheless,theseideaswereadaptedandimprovedbytheAmericanbridgeengineerRoeblingwhousedcablestaysinconjunctionwiththedrapedsuspensioncableforthedesignofhisbridges.（时间顺序介绍斜拉索历史）inclinedstays斜拉索；bridgedeck桥面板；Slack松弛；wind-inducedoscillations风振；gale

狂风；

inconjunctionwith连接7.1BridgeEngineering

ThebestknownofRoebling’sbridgesistheBrooklynBridge,completedin1883.Themodernconceptofthecable-stayedbridgewasfirstproposedinpostwarGermany,intheearly1950s,forthereconstructionofanumberofbridgesovertheRiverRhine.Thesebridgesprovedmoreeconomic,formoderatespans,thaneitherthesuspensionorarchbridgeforms.Itprovedverydifficultandexpensiveintheprevailingsoilconditionsofanalluvialfloodplaintoprovidethegravityanchoragesrequiredforthecablesofsuspensionbridges.Similarlyforthearchstructure,whetherdesignedwiththearchthrustcarriedatfoundationlevelorcarriedasatiedarch,substantialfoundationswererequiredtocarrytheselargeheavyspans.Bycomparisonthecable-stayedalternativeshadlightdecksandthetensilecableforceswerepartofaclosedforcesystemwhichbalancedtheseforceswiththecompressionwithinthedeckandpylon.Thusexpensiveexternalgravityanchorageswerenotrequired.（时间顺序介绍斜拉索历史）moderatespans中等跨度；prevailingsoilconditions常见的土壤条件；alluvialfloodplain冲积平原；archthrust拱推力；pylon桥塔7.1BridgeEngineering

7.1.3SuspensionBridgeThescopeofthisunitisrestrictedtoconsiderationoftheclassicalthree-spansuspensionbridgeconfiguration(Fig.7-2),withastiffenedload-carryingdeckstructuresupportedbyearth-anchoredcables.Thebridgemayhavesidespansofdifferinglengthsand,dependingonthesitetopography,thebridgedeckmaybesuspendedeitherinallthreespansorinthemainspanonly,whenthesidespancablesactsimplyasbackstaystothetowers.Bridgeswithunusualspanorcableconfigurations,includingbridgeswithmultiplemainspans,mono-cablebridges,self-anchoredstructures,andhybridpartsuspension/partcable-stayedstructuresarenotconsidered.Evenwiththeabovelimitations,itisnotpossibleinarelativelyshortchaptertoconsiderindetailmanyimportantaspectsofsuspensionbridgedesign–inparticulartheanalysisofcablesandtheaerodynamicdesignrequirements.（悬索结构介绍）three-spansuspensionbridgeconfiguration三跨吊桥结构；earth-anchoredcables地锚；sidespans边跨；topography地形；mainspans主跨；mono-cable单索；self-anchored自锚式7.1BridgeEngineering

Twoormoremaincablesformedfromhigh-strengthsteelwires,

withastrength-to-weightratioofaroundthreetimesthatofweldablestructuralsteels,andwhichsupportthetraffic-carryingdeckandtransferitsloadingbydirecttensionforcestothesupportingtowersandanchorages.

Asthedeckdeadloadisentirelysupportedbythecable,towersandanchorages,

aneconomicaloveralldesignrequiresthelightestpracticabledeckstructure

whichissupportedfromthemaincablesbyhangersofhigh-strengthwireropesorstrandthatarespacedatregularintervalsthroughoutthespans.悬索桥设计原则Weldable焊接的；traffic-carryingdeck桥面板；supportingtowersandanchorages支撑塔架和锚固；deadload恒载；overalldesign总体设计；wireropes钢丝绳；

spacedatregularintervals等间隔放置7.1BridgeEngineering

Withcablesconstructedfromveryhigh-strengthsteelloadedindirecttensionastheirprimaryload-carryingmembers,suspensionbridgesareideallysuitedtolongerspans,andthisisthereforetheprimaryapplicationforthistypeofstructure.Althoughcable-stayedstructureshavemadeconsiderableinroadsintothespanrangepreviouslyconsideredtobethedomainofsuspensionbridges,theseremaintheunchallengedchoiceforspansover1200m.Whenwelldesignedandproportioned,suspensionbridgesarethemostbeautifulofbridges,asthesimplicityofthestructuralarrangement,thenaturalcurveofthemaincables,theslendersuspendeddeckandtowers,produceanaestheticallyattractivestructure.Thisnaturalgracecanalsomakesuspensionbridgesasuitablechoiceforrelativelyshort-spanfootbridgesinsituationswhereanattractiveappearanceisanimportantconsideration.（悬索结构的优势）Inroads侵入，损耗；directtension直接受拉；naturalcurve自然曲线；aestheticallyattractive美观，吸引人7.1BridgeEngineering

7.2.1SeismicDesignandAnalysisofUndergroundStructureThisreportfocusesonrelativelylargeundergroundfacilitiescommonlyusedinurbanareas.Thisincludeslarge-diametertunnels,cut-and-coverstructuresandportalstructures(Fig.7-3).Thisreportdoesnotdiscusspipelinesorsewerlines,nordoesitspecificallydiscussissuesrelatedtodeepchamberssuchashydropowerplants,nuclearwasterepositories,minechambers,andprotectivestructures,thoughmanyofthedesignmethodsandanalysesdescribedareapplicabletothedesignofthesedeepchambers.本报告重点内容

Portal洞门；pipelines管道；sewer下水道；chambers内庭；hydropower水力发电；repositories贮藏室7.2UndergroundEngineering

Large-diametertunnelsarelinearundergroundstructuresinwhichthelengthismuchlargerthanthecross-sectionaldimension.Thesestructurescanbegroupedintothreebroadcategories,eachhavingdistinctdesignfeaturesandconstructionmethods:(1)boredorminedtunnels;(2)cut-and-covertunnels;and(3)immersedtubetunnels.Thesetunnelsarecommonlyusedformetrostructures,high-waytunnels,andlargewaterandsewagetransportationducts.大直径隧道分类Categories种类；distinct不同的；immersed沉入的；metro地铁；sewage下水道7.2UndergroundEngineering

Cut-and-coverstructuresarethoseinwhichanopenexcavationismade,thestructureisconstructed,andfillisplacedoverthefinishedstructure.Thismethodistypicallyusedfortunnelswithrectangularcross-sectionsandonlyforrelativelyshallowtunnels(<15mofoverburden).Examplesofthesestructuresincludesubwaystations,portalstructuresandhighwaytunnels.Immersedtubetunnelsaresometimesemployedtotraverseabodyofwater.Thismethodinvolvesconstructingsectionsofthestructureinadrydock,thenmovingthesesections,sinkingthemintopositionandballastingoranchoringthetubesinplace.大直径隧道建造方法excavation挖掘；shallow浅；overburden覆盖层；traverse移动；

sinking下称7.2UndergroundEngineering

Thisreportdoesnotcoverissuesrelatedtostaticdesign,althoughstaticdesignprovisionsforundergroundstructuresoftenprovidesufficientseismicresistanceunderlowlevelsofgroundshaking.Thereportdoesnotdiscussstructuraldesigndetailsandreinforcementrequirementsinconcreteorsteelliningsforundergroundstructures.Thereportbrieflydescribesissuesrelatedtoseismicdesignassociatedwithgroundfailuresuchasliquefaction,slopestabilityandfaultcrossings,butdoesnotprovideathoroughtreatmentofthesesubjects.

Thereaderisencouragedtoreviewotherliteratureonthesetopicstoensurethatrelevantdesignissuesareadequatelyaddressed.本报告没有涉及到的内容provisions规范；

briefly简要的；liquefaction液化；fault断层；

thorough彻底的；literature文献7.2UndergroundEngineering

7.2.2PerformanceofUndergroundFacilitiesDuringSeismicEventsTunnelsaremorestableunderasymmetricload,whichimprovesground-lininginteraction.Improvingthetunnelliningbyplacingthickerandstiffersectionswithoutstabilizingsurroundingpoorgroundmayresultinexcessseismicforcesinthelining.Backfillingwithnon-cyclicallymobilematerialandrock-stabilizingmeasuresmayimprovethesafetyandstabilityofshallowtunnels.隧道在地震作用下的性能Symmetric对称的；excess过度的；Backfilling回填；stability稳定性7.2UndergroundEngineering

The1995Hyogoken-NambuEarthquakecausedamajorcollapseoftheDaikaisubwaystationinKobe,Japan.Thestationdesignin1962didnotincludespecificseismicprovisions.Itrepresentsthefirstmodernundergroundstructuretofailduringaseismicevent.Fig.7-4showsthecollapseexperiencedbythecentercolumnsofthestation,whichwasaccompaniedbythecollapseoftheceilingslabandthesettlementofthesoilcoverbymorethan2.5m.日本神户地铁站1995年发生的倒塌事故collapse倒塌；

modern现代的；accompanied伴随；ceiling天花板；settlement沉降7.2UndergroundEngineering

Duringtheearthquake,transversewallsattheendsofthestationandatareaswherethestationchangedwidthactedasshearwallsinresistingcollapseofthestructure.Thesewallssufferedsignificantcracking,buttheinteriorcolumnsintheseregionsdidnotsufferasmuchdamageunderthehorizontalshaking.Inregionswithnotransversewalls,collapseofthecentercolumnscausedtheceilingslabtokinkandcracks150-250mmwideappearedinthelongitudinaldirection.Therewasalsosignificantseparationatsomeconstructionjoints,andcorrespondingwaterleakagethroughcracks.Fewcracks,ifany,wereobservedinthebaseslab.地铁站倒塌的详细情况transverse横向的；

significant重大的；interior内部的；longitudinal纵向的；

separation分离；joints节点；leakage泄漏7.2UndergroundEngineering

Itislikelythattherelativedisplacementbetweenthebaseandceilinglevelsduetosubsoilmovementcreatedthedestructivehorizontalforce.Thistypeofmovementmayhaveminoreffectinasmallstructure,butinalargeonesuchasasubwaystationitcanbesignificant.Thenon-linearbehaviorofthesubsoilprofilemayalsobesignificant.Itisfurtherhypothesizedthatthethicknessoftheoverburdensoilaffectedtheextentofdamagebetweensectionsofthestationbyaddinginertialforcetothestructure.

Othersattributethefailuretohighlevelsofverticalacceleration.下层土运动引起的水平力是破坏性的destructive破坏性的;profile剖面；hypothesized假定；attribute把······归于7.2UndergroundEngineering

SeveralhighwaytunnelswerelocatedwithinthezoneheavilyaffectedbytheSeptember21,1999ChiChiearthquake(ML7.3)incentralTaiwan.Thesearelargehorseshoeshapedtunnelsinrock.Allthetunnelsinspectedbythefirstauthorwereintactwithoutanyvisiblesignsofdamage.ThemaindamageoccurredattunnelportalsbecauseofslopeinstabilityasillustratedinFig.7-6.Minorcrackingandspallingwasobservedinsometunnellining.OnetunnelpassingthroughtheChelungpufaultwasshutdownbecauseofa4-mfaultmovement.NodamagewasreportedintheTaipeisubway,whichislocatedover100kmfromtherupturedfaultzone.台湾的地下结构在地震中的性能horseshoe马蹄型;inspected检查；intact完整的；spalling剥落；ruptured破裂的7.2UndergroundEngineering

TheAugust17,1999KocealiearthquakewasreportedtohavehadminimalimpactontheBolutunnel.Theclosurerateofonemonitoringstationwasreportedtohavetemporarilyincreasedforaperiodofapproximately1week,thenbecamestableagain.Additionally,severalhairlinecracks,whichhadpreviouslybeenobservedinthefinallining,werebeingcontinuouslymonitoredforadditionalmovementandshowednomovementduetotheearthquake.

TheNovember12,1999earthquakecausedthecollapseofbothtunnels300mfromtheireasternportal.Atthetimeoftheearthquake,a800-msectionhadbeenexcavated,anda300-msectionofunreinforcedconcretelininghadbeencompleted.Thecollapsetookplaceinclaygaugematerialintheunfinishedsectionofthetunnel.Thesectionwascoveredwithshotcrete(sprayedconcrete)andhadboltanchors.土耳其的地下结构在地震中的性能closure关闭；temporarily暂时；hairline极细的；excavated挖掘；shotcrete喷浆混凝土7.2UndergroundEngineering

TheDaikaisubwaystationcollapsewasthefirstcollapseofanurbanundergroundstructureduetoearthquakeforces,ratherthangroundinstability.UndergroundstructuresintheUShaveexperiencedlimiteddamageduringtheLomaPrietaandNorthridgeearthquakes,buttheshakinglevelshavebeenmuchlowerthanthemaximumanticipatedevents.Greaterlevelsofdamagecanbeexpectedduringthesemaximumevents.StationcollapseandanticipatedstrongmotionsinmajorUSurbanareasraisegreatconcernsregardingtheperformanceofundergroundstructures.Itisthereforenecessarytoexplicitlyaccountforseismicloadinginthedesignofundergroundstructures.地下结构在地震中性能总结Instability不稳定性；

anticipated预期的；explicitly明确的7.2UndergroundEngineering

7.3TrafficEngineering

7.3.1IntroductionTrafficcanbedefinedasthemovementofpedestriansandgoodsalongaroute,andinthe21stcenturythebiggestproblemandchallengeforthetrafficengineerisoftentheimbalancebetweentheamountoftrafficandthecapacityoftheroute,leadingtocongestion.Trafficcongestionisnotanewphenomenon.RomanhistoryrecordsthatthestreetsofRomeweresocloggedwithtrafficthatatleastoneemperorwasforcedtoissueaproclamationthreateningthedeathpenaltytothosewhosechariotsandcartsblockedtheway.Morerecentlypicturesofourmoderncitiestakenattheturnofthecenturyshowstreetscloggedwithtraffic.Thedictionarydescribes’traffic’asthetransportationofgoods,comingandgoingofpersonsorgoodsbyroad,rail,air,etc.Oftenincommonusageweforgetthiswiderdefinitionandcolloquiallyequatethewordwithmotorisedroadtraffic,totheexclusionofpedestriansandevencyclists.Trafficengineeringisconcernedwiththewiderdefinitionoftraffic.congestion拥挤；proclamation

公告；chariots二轮战车；carts

二轮马车；colloquially

口语地；Thedefinitionremainsvalidtodaybuttherehasclearlybeenachangeintheemphasisintheroleoftheengineerinthetime.Inthe1970sthecarwasseenasthefutureandthefocuswasverymuch‘predictandprovide’.Trafficengineersweretaskedwithincreasingthecapacityofthehighwaysystemtoaccommodatewhatseemedandendlessgrowthinmotortraffic,oftenattheexpenseofotherroadusers.Roadcapacityimprovementswereoftenachievedattheexpenseofpedestrianfreedomofmovement,pushingpedestrianstobridgesandunderpassessothatthesurfacecouldbegivenovertothecar.However,itisnowgenerally,butbynomeansuniversallyrecognizedthatwewillneverbeabletoaccommodateunconstrainedtraveldemandbycarandsoincreasinglytrafficengineeringhasbecomefocusedonsharingspaceandensuringthatmoresustainableformsoftransportsuchaswalkingandcyclingareadequatelycateredfor.交通定义的变化weretaskedwith受…挑战；unconstrained无约束的7.3TrafficEngineering

Tarhasbeenusedformanyyearsinroadconstructionbothasabinderformacadamandasasurfacedressinginitiallyonwater-boundroads.RoadtaristodayspecifiedinBS761bythefollowingdefinition:‘tarforuseinroadworkispreparedentirelyfromcrudetarsproducedwhollyorsubstantiallyasaby-productinthecarbonisationofcoalatabove600°Cinexternallyheatedretortsorcokeovens’.公路路面材料介绍Tar柏油；binder

粘合剂；macadam碎石；crude粗糙的；天然的；carbonization碳化作用；retorts曲颈瓶；cokeovens

炼焦炉7.3TrafficEngineering

Concretepavementsareconstructedinavarietyofformsbyseveraldifferentconstructionmethods.Theymaybereinforcedorunreinforced;ifreinforcedthesteelmaytaketheformofindividualbarsorweldedmesh.Theslabsmaycontainseveraldifferenttypesofjointortheymaybeunjointedorcontinuous.Constructionmaybecarriedoutbytheconventionalside-formprocessusingaconcretingtrainwithmanydifferingunits,oroneofseveralformsofslip-formpavermaybeemployedoperatingwithaminimumofadditionalequipment.混凝土路面施工weldedmesh焊接网；slabs

板材；conventional传统的；7.3TrafficEngineering

TheimportanceofadequatedrainagewasrealisedbyRomanroadbuilders,butafterthedeclineoftheRomanEmpirethestandardofhighwayconstructioninEuropedeclinedandplanneddrainagebecamealmostnon-existent.Withtheadventofindustrialisationincreasingattentionwaspaidtotheremovalofsurfacewaterandtheloweringofthewater-tablebeneaththepavement.IntheUnitedKingdomthepioneerroad-buildingofTelfordandMacadamlaidstressontheincorporationofacamberorcrownintotheroadsothatsurfacewatercouldbequicklyremoved.Increasingurbandevelopmentmadeopenditchesinappropriateandledtotheincreasinguseofroadgulleysconnectedtoroadsewersasthemeansofremovingsurfacewater.Improvementsinthequalityofroadmaterialshaveresultedinimperviouspavements,makingtheproblemofsub-soilusuallygreatestinthecuttings,wherecut-offdrainageisrequired.路面排水系统介绍industrialisation工业化；camber

弧形；ditches沟渠；gulleys

集水口；imperviouspavements

不透水路面；7.3TrafficEngineering

Asiteinvestigationisanessentialfirststepinthedesignofanyhighwayonanewlocation.Theinformationobtainedbythesurveyassistsinlocatingthehighwaytoavoidadversegeologicalconditionsandindesigningearthworks,pavementthickness,drainageworksandbridgefoundations.实地勘测adversegeologicalconditions不良地质条件；earthworks

土方工程；7.3TrafficEngineering

Withthedrainageworkscompletedandallservicesandductscrossingthecarriage-wayinplace,theformationmaybesealedtoprotectthesubgradefromexcessivemoisturechanges.Thisisbecauseacohesivesubgradewhichhasbecomeexcessivelydryduetoevaporationduringadryconstructionseasonmayswellwithsubsequentincreasesinmoisturecontent,resultingindifferentialmovementofthepavement.Ontheotherhandasubgradethathasbecomeexcessivelywetisdifficulttocompactandtooverlaywithsub-basematerial.铺面施工formation地层；duct管道；seal

密封；subgrade路基；

excessive过度的；cohesive有粘着力的；evaporation

蒸发；swellwith膨胀，充满；7.3TrafficEngineering

Thetwentiethcenturyhasseenaconsiderableimprovementinthematerialsandconstructionaltechniquesusedforhighwaypavements.Thishasresultedinadramaticincreaseinthelifeofapavementfromtheperiodwhenanannualsurfacedressingwasnecessarytomaintaintheshapeofthepavementtothepresenttimewhendesignlivesoffromfivetotwentyyearsarecommonforheavilytraffickedhighways.路面养护介绍dramatic急剧的；trafficked

行车的；7.3TrafficEngineering

Everytripbyavehicleresultsinaparkingactattheendofthetrip.Theimportanceofparkingcanperhapsbeillustratedbythefactthat,onaverage,acarintheUKisparkedforabout23hoursaday.Thevehiclemaybeparkedonthestreetoroff-streetinacar/lorry/cyclepark,orinaprivategarage.Howvehiclesarriveanddepartfromtheseparkingplaces,howlongtheystayandunderwhatcircumstancesdefinevehiculartrafficandindeedsomepedestriantrafficontheroadsandhelptodeterminewhatmeasuresarerequiredtomeetormanagethedemand.Therefore,itisveryimportanttoobtainanobjectiveandunbiasedunderstandingofthisactivitybyproperlyconstructedandconductedsurveys.停车情况调查的必要性unbiased公正的；7.3TrafficEngineering

Theestimationoftraveldemandisafundamentalpartoftrafficengineeringdesignwork.Thekeyquestionsarehowmucheffortneedstobeexpendedinestimatingdemandandwhatmethodshouldbeadopted.Theanswersdependonthenatureofthedesignissues.Forexample,aminortrafficmanagementdesigntoimproveroadsafetyoveralengthofroadininnerLondonwheretrafficflowshavebeenstableformanyyearswillrequirelittlemorethanasurveyofexistingtraffic.Thereverseistrueofaproposalforanewroadwaytoassistregenerationinanoldurbanareawheredesignwilldependonestimatingthenewtrafficlikelytobeattractedtousethenewroad.出行需求估计littlemorethan仅仅是；regeneration

重建；7.3TrafficEngineering

Thetermcapacitywhenreferringtoahighwaylinkorjunctionisitsabilitytocarry,accommodateorhandletrafficflow.Traditionally,capacityhasbeenexpressedinnumbersofvehiclesorpassengercarunits(PCU).(Vehiclesvaryintheirperformanceandtheamountofroadspacetheyoccupy.ThebasicunitisthepassengercarandothervehiclesarecountedastheirPCUequivalent,e.g.abusmightbe3PCUsandapedalcycle0.1PCU.)Inrecentyearspublictransportoperatorshaveappliedpressuretoconsiderhighwaysintermsoftheirpassenger-handlingcapacityandthusgiveagreateremphasistothebenefitsofusinghighoccupancyvehicles,suchasbusesortrams.通行能力分析operators经营者；occupancy

占用；7.3TrafficEngineering

Trafficsignalsareusedtoregulateandcontrolconflictsbetweenopposingvehicularorpedestriantrafficmovements.Withouttheuseofsignalsatsomesitesthemajorflowwoulddominatethejunction,makingentriesfromtheminorroadimpossibleorverydangerous.Atothersitestheminorroadmightinterferewiththeflowofmajorroadtraffictosuchanextentthatexcessivecongestionwouldoccur.Trafficsignalscannotonlyimprovejunctioncapacity,butcanalsoimproveroadsafety.Thetrafficengineerwillneedtoknowhowbesttoprovid