transportation and traffic congestion(交通堵塞)

WangYantianXuGuodongHeHaohongINTRODUCTION:Themovementofpeopleandgoodswithinacityisaspecialareaoftransportationwithuniquecharacteristics.Severalmodesoftransportationcompeteorcomplementeachotherinprovidingtransportationservicesinthecity.Adensenetworkoftransportationservicesaffectstheefficiencyofoperationinanurbanareathatcausestrafficcongestion.Thereisadirectconnectionbetweentransportationandthecitygrowth.Pollutionandcongestionareadditionalcostsrelatedtotransportation.•Effectofpollutionaretwofold:negativeeffectsonhealthofhumans,animalsandvegetationandexpenditureforpollutionreductionandcleanup.Congestionproduceswastedproductivetimeduetotheextendedtraveltime.Privateautomobile:Thisinvolvesdrivealone,drivewithapassengerorpassengersinaprivatecar.Carpoolingistheorganizedcommutewithaminimumoftwopeopleinthevehicle.Mostcommonformofcarpoolingistheintra-householdwheretwoormorememberofthehouseholdutilizesamecar.Carpoolingbetweenco-workersislesspopulardespiteitspotentialtoreducecongestiononroadways.VanPooling:ThisisvoluntaryorcompanyOrganizedcommutetowork.Eitheragroupofindividualsagreetoleaseavanfromaproviderorcompanyprovidestransportationtoandfromwork.Inseveralareaswherethereisseverecongestionontheroadways,pressureisappliedontheemployerstoreducethenumberoftripsgeneratedbytheiremployeesthroughtheinstitutionofcarandvanpools.Thisreducescongestionontheroadways.Taxis:Theseareeitherowneroperatedorprivatelyownedthatprovidetransportationtothegeneralpublic.Majormarketsfortaxisaretourists,visitor,andbusinesspeople.Alsoforpeopleinahurryandpeoplewhodonotneedacarattheirdestinationtendtohiretaxiservice.Buses:Theseusuallyarepubliclyownedmasstransitsystemusedforschoolchildrentransportation,labortransportationandcompanysponsoredworkerstransportationfromthesuburbstotheworkplaces.Thesecanreducecongestionconsiderablyifusedbythepubliconaregularbasis.LightRail,RailRapidTransitSystem,commuterRailway,AirandWaterServices:Allthesemodeshelpreducingthetrafficcongestionontheroadwaysinthecities.Parkandridewhereindividualsparktheirvehicleandthenridepublictransportation,vanpoolsorcarpoolaremadeavailablealso.TWOREPRESENTATIONSOFURBANNETWORKSYSTEMPrimal:intersections(orsettlements)areturnedintonodesandroads(orlinesofrelationship)areturnedintoedges.Dual:roadsareturnedintonodes,intersectionsareturnedintolinksbetweenthecorrespondingnodes.TWOREPRESENTATIONSOFURBANNETWORKSYSTEMPrimalintuitive,thevalueofdistancecanbeeasilyassociatedtoedges.Butitcannotcharacterizethecommonnotionof“mainroads”inurbantrafficsystems.Itviolatestheintuitivenotionthatanintersectioniswheretworoadscross,notwherefourroadsbegin.Dualonecanhavemany“conceptuallycountless”edgesforeachnode.Thisleadstotherecognitionofscale-freebehaviorforthedegreedistributionofurbanstreetnetworks.TRAFFICPROBLEM:AtpresentaboutmillionstripsaremadebytheChinesepeopleperday.Manyofthesetripsaremadebyprivatevehicles.Heavytruckscarryfreightintoandoutofthecitiesandsmallertrucksareusedforthelocaldeliveries.Manycitieshaveportsandairportswhicharetheprimaryentryorexitpointsforpassengersandcargooriginatingfromordestinedtoabroadarea.Allthesefunctionsgeneratesubstantialtrafficloadsandcongestionstotheurbanroadnetworks.Severaltransportationproblemsplaguecontemporaryurbanareas,themostprevalentbeingtrafficcongestion.Trafficcongestioniscreatedonfixedcapacityroadnetworkswhentrafficgrowsaboveacertainthreshold,afterwhichthelevelofservicedeterioratestounacceptablelevels.Capacityofroadwaysystemistoalargeextentdeterminedbytransportationsystemcharacteristicsandpoliciessuchasgeometry,signalizationcharacteristics,andtrafficmanagementrestrictions.Thecapacityisalsodeterminedbythedrivinghabitsofthedrivers.WHAT’SWRONG?•1.TrafficGrowth:Trafficcongestionisdirectlyrelatedtothetrafficgrowth.Therearefourcomponentsoftrafficgrowth.•2.Thenaturalgrowthofthepopulation:Asthepopulationgrows,morevehiclesareontheroadproducingcongestionunlessroadwaysareimproved•3.LocationPatterns:Thisisduetospatialdistributionofresidence,work,shopping,andentertainmentplaces.•4.TransportationSystem,CharacteristicsandPolices:Speedlimitsimposedbycityandstate,signalingservicewaittimes,establishmentofcarpool,buslanesetc.affectsthetrafficgrowthalso.Thetransportationbehaviorofpeopleisaffectedbythecharacteristicsandnormsofindividualsandhouseholds,whichalongwiththelocationalpatternsofplacesadactivitiesareaffectedbytheevolutionofthesociety,economyandthetechnologyataregionalandnationallevel.TrafficCongestionTrafficGrowthRoadwayCapacityGrowthEffectsLocationalPatternsTransportBehaviorHouseholdCharacteristicsAndNormsEvolutionofSociety,Economy&TechnologyTransportationSystemEFFECTSOFTRAFFICCONGESTION:•Lossofproductivetime•Lossoffuel•Increaseinpollutants:Theretwowaysthepollutantsincrease.Oneduetomoregasburntduetothetrafficcongestion,andsecondthereismoretimeisspentwhentheengineisidleorstopandgotraffic.•IncreaseinwearandtearoftheautomobileenginesHighpotentialfortrafficaccidents•Slowandinsufficientemergencyresponse•People’smoodsareoftenaffected,whichhasnegativeimpactsonproductivityat