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CHANGSHAUNIVERSITYOFSCIENCE&TECHNOLOGY毕业设计(论文)资料附件:外文文献原文及译文学生姓名:学号:班级:专业:土木工程(桥梁方向)指导教师:2010年3月WhatistrafficengineeringTrafficengineeringisstillarelativelynewdisciplinewithintheoverallboundsofcivilengineering.ithasneverthelessalreadybeenpartiallyplanning.thedisciplinesarenotsynonymousthough.transportationplanningisconcernedwiththeplanning,functionaldesign,operationandmanagementoffacilitiesforanymodeoftransportationinordertoprovideforthesafe,rapid,comfortable,convenient,economicalandenviromenally-compariblemovementofpeopleandgoods.withinthatbroadscope,trafficengineeringdealswiththosefunctionsinrespectofroads,roadnetworks,terminalpoints,aboutlandsandtheirrelationshipswithothermodesoftransportation.Thosedefinitions,basedonthe1976onesoftheU.S.instituteoftransportationengineersarecompletethan,theBritishinstitutingofcivilengineeringwhichdealswithtrafficplanninganddesignofroads,offrontagedevelopmentandofparkingfacilitiesandwiththecontroloftraffictoprovidesafe,convenientandeconomicalmovementofvehiclesandpedestrians.Thedefinitionsofthedisiciplinearebecomingclearer:themethodologyisdevelopingcontinuouslyandbecomingincreasinglyscientific.theearlyrule-of-thumbtechniquesaredisappearing.TrafficproblemThedisciplineisyoung:theproblemislargeandstillgrowing.in1920thetotalnumberofmotorvehicles,licensedingreatBritainwas,650,000.fiftyyearlaterthecomparablefigurewas14,950,000-agrowthfactorof23times.inrecentyearstherateofgrowthhasslackenedsomewhat,butitisstillconsiderable:19556,466,00019609,439,000196512,938,000197014,950,000197417,247,000Inordertoseetheproblemineverydayterms,considerhighstreet.anywhere.assumingthatpresenttrendscontinue,itisexpectedthatwithinthenextfifteenyearsofsothetrafficonthisroadwillincreasebyaroundfortytofiftypersent.ifthisincreasedvolumeoftrafficweretobeaccommodatedatthesamestandardastoday,theroadmightneedtobewidenedbyasimilarfortytofiftypercent-perhapsextralaneoftrafficforthepedestriantocross.Inmancases,toaccommodatetheforeseeablefuturedemandwoulddestroythecharacterofthewholeurbanenvironment,andisclearlyunacceptable.thetrafficproblemisofworld-wideconcern,butdifferentcountriesareobviouslyatdifferentstagesinthetrafficescalation-withAmericainthelead,whileacountyhasfewroadsandarelativelylowproblem,assoonasthecountryisopenedupbyaroadsystem,thestandardoflivingandthedemandformotortransportbothrise,gatheringmomentumrapidly.eventually-andthestageatwhichthishappensisopentoconsiderabledebate-thedemandforcars,busesandlorriesbecomesatiated.thestageisknownassaturationlevel.Forcomparison,carownershipfiguresindifferentcountriesin1970were:India0.01cars/personIsrael0.05cars/personJapan0.09cars/personIreland0.13cars/personNetherlands0.20cars/personGreatBritain0.21cars/personWestGermany0.23cars/personAustralia0.31cars/personUSA0.44cars/personButthegrowthinvehicleownershipisonlypartoftheoveralltrafficproblem.obviously,ifacountryhasunlimitedroadsofextremewidth,thetrafficproblemwouldnotrise.nocountryintheworldcouldmeetthisrequirement:apartfromanythingelse,itwouldnotmakeeconomicforeachvehicleusingtheroads.Thisfigureisdecreasingsteadily.ThreepossiblesolutionsThebasicproblemoftrafficisthereforesimple-anever-increasingnumberofvehiclesseekingtousetoolittleroadespace.thesolutiontotheproblem-iselseanot-too-difficultchoicefromthreepossiblilities:build,sufficientroadsofsufficientsizetocopewiththedemand.Restrictthedemandforroadsbyrestrictingthenumbersoflicensedvehicles.Acompromisebetween(a)and(b)buildsomeextraroads,usingtheandtheexistingroadnetworktotheirfullpotential,andatthesametimeapplysomerestraintmeasures,limiting,theincreaseindemandasfaraspossible.Withnovisibleendtothedemandyetinsight,and216withmodernroad-makingcostsrangingaround£1millionperkilometercostofbuildingroadsinBritaintocopewithanunrestricteddemandwouldbefartoogreat.addedtothis,suchclossaluseofspaceinacrowedislandcannotbe,seriouslyconsidered.inLosAngeles,acitybuiltaroundtheparkingspacefor,theautomobile.ourcitiearealreadylargelybuilt-andnoonewouldconsiderruiningtheircharacterbypullingthemdownandrebuildingaroundthecar,thusthefirstpossiblesolutingisruleout.Eventoday,inanageofatleastsemi-affluenceinmostoftheWesternWorld,thecarisstilltosomeextentastatussymbol,asymbolofprestige.everyfamilywantstoownone,andtakesstepssavingorborrowing-togetone.asincomesandstandardsrisethesecondcarbecomesthetarget.anymovetorestricttheacquisitionoftheprivatecarwouldbemostunpopular-andpoliticallyunlikely.Formanypurposetheflexibilityoftheprivatecar-conceptuallyaffordingdoor-to-doorpersonaltransportisideal,anditsusecanbeaccommodate.forthemass,movementofpeoplealongspecificcorridorswithinalimitedperiodoftime-i.e..particularlythejourneytoworkitmaybelesseasilyaccommodated.othertransportmodemaybemoreefficient.somesortofcompromisesolutionistheinevitableanswertothebasictrafficproblem.itisintheexecutionofthecompromisesolutionthat,trafficengineeringcomesintoitsown.trafficengineeringensuresthatanynewfacilitiesarenotover-deignedandarecorrectlylocatedtomeetthedemand.itensuresthattheexistingfacilitiesarefullyused,i
本文标题:土木工程桥梁方向毕业设计外文及翻译
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