交通工程学课件chp3traffic studies final

Chapter3

TrafficStudies（交通调查）PurposesofTrafficStudiesInventoriesofphysicalsystems,suchascontroldevices,etc.Investigatingtrendovertimesothatactionscanbeanticipated,identifiedandtaken(volume,speed,accidents,….)Calibrationofrelationsorparameters,suchasreactiontime,frictionfactor,…Assessingtheeffectivenessofimprovement,suchasaccidentreduction,HOV…TypesofTrafficStudiesVolumeStudySpeedStudyDensityStudyDelay/TravelTimeStudyCapacityStudyOriginDestination(O-D)StudyOtherSpecialStudiesAccidentParkingPedestrian3-1VolumeStudy（交通量调查）PurposesofVolumeStudyAnnualTrafficVolumeAnnualtraffictrend;estimateannuale(tollroads,收费道路)ADT/AADTTransportsystemvs.demand（需求）;improvementoffacilitiesHourlyTrafficVolumePeakhourtrafficflow;lackofcapacity;trafficmanagementmeasuresShort-termTrafficFlowFlowrate;variationoftrafficwithinthepeakhourVolumeStudyDataCategories(Two-way)VolumeDirectional（分流向）DistributionCapacityanalysis;signaltiming（信号配时）TurningMovementVehicleTypeVehicleoccupancy（占有率）PedestrianCordon（境界出入）andScreenline（分隔核查线）studiesVolumeStudyTechniquesTally（计数）SheetsMaximummanpowerHandCountersFloatingCar(ProbeVehicle）（浮动车）MechanicalCounters(e.g.,Pneumatictubecounters,压力管式检测器)PermanentCounters(e.g.,loopdetectors,线圈检测器)OtherModernMethodsRadar,ultrasonic,imageprocessing,…FloatingCarMethod（浮动车法）ManualMethodorAutomatic(e.g.,floatingcellulardatatodeterminespeed)ManualMethodRequirements:onevehicle,onedriver,and3observersOneoftheobserverscountsing（对向）traffic(Xa)Anothercountsthenumberofvehiclespassing(Y1)orpassedby(Y2)thefloatingcar(Yc=Y1-Y2)Theotherrecordstimeandtraveltime(ta,tc)FloatingCarMethodEquationsVolumeAveragetraveltimeAveragespeedExample3-1,P42PneumaticTubesComponentsHollowrubbertubesVehiclecounterorclassifierFeaturesEasilyandquicklyinstalledInexpensiveReasonablyreliableInductiveLoops（感应线圈）ComponentsShieldedloopwireLead-incableDetectorunitConsiderationsMustsawthepavementFailurerateFixedlocationDetectspresenceMeasuresspeedApplicationsPermanentCountStationsIntersectionDetectionFreewaymonitoringOtherCountingDevicesTimeofVolumeStudy24-hrStudyAconsecutive24-hrstudybetweennoonofMondayandnoonofFriday16-hrStudy6amto10pm12-hrStudy7amto7pmPeakHourStudy7amto9am,4pmto6pmWeekend12pm(or6pm)ofFridayto12pm(or6am)ofMondayIntersectionVolumeStudyTimeofStudy:PeakhourManualMethodAtleastoneobserverforeachentrance(leg)Threeobserversforhightrafficentrancestocountthrough,leftturn,andrightturnvehicles.RoadNetworkVolumeStudyTypesofVolumeCountStationsControlStation（控制性观测站）ToobtainADTMonthly(7daystoamonth)orquarterly(7consecutivedays/quarter)countsTemporaryStation（临时观测站）Toobtainsample(coverage)countsAtpointsofsignificantchangealongthetrafficvolumerouteprofile,onfreewayrampsandconnectors,onroadswhichintersecthighwaysandatothernecessarylocationsRequiredfactoringtoAADTtosevermostneeds3-2SpeedStudy（车速调查）TypesandPurposesofSpeedStudySpotSpeedStudy（地点车速调查）Spotspeedstudiesareconductedtoestimatethedistributionofspeedsofvehiclesinastreamoftrafficataparticularlocationonahighway.Usedfor:Establishtheeffectivenessofneworexistingspeedlimitsand/orenforcementpracticesEstablishtrendstoassesstheeffectivenessofnationalpolicyonspeedlimitsandenforcementSpecificdesignapplications(likesightdistance)Specificcontrolapplications(yellow/allredtiming–thesizeofdilemmazonedependsonspeed)Investigationofhigh-accidentlocationsatwhichspeedissuspectedtobeacausativefactorTypesandPurposesofSpeedStudySpaceSpeedStudy（区间车速调查）EvaluateroadwayLevelofServiceUsedtoimprovealignmentdesignParameterfordeterminingefficiencyoftrafficoperationsUsedintrafficassignment(transportationplanning)UsedtodeveloptrafficmanagementmeasuresandsignaltimingEvaluatetheeffectivenessofmeasuresTrafficflowparameterSpotSpeedStudyMeasurespeedatspecificlocationsRecordspeedofindividualvehiclesastheypassTimeMeanSpeed(TMS)Location:generallyonstraightsegmentwithoutanydisturbance（无干扰）TimetoConductStudyGenerallyattimeswhentrafficflowratesarelessthan750-1000vphplforfreewaysOnehourbetween9:00–11:30,14:30–16:00,19:00–21:00SpotSpeedStudySampleSize（样本大小）Larger

than50(or100)InappropriateMeasureofSpotSpeedsAlwayspickthefirstvehicleoftheplatoon,whichtendstohavelowerspeedTendtomeasurespeedsofacertaintypeofvehicle(e.g.,trucks)TendtomeasurehighspeedvehiclesSpotSpeedStudyMethodsofcollectingManualAutomaticRadarLaserPiezo-electricImageprocessingRunningSpeedorSpaceSpeedStudyRunningSpeed（行驶速度）TheoverallspeedexclusiveofstopsSpace

Speed（区间速度）IncludestopsOveralltravelspeedMethodsofCollectingLicenseplate（牌照法）Floatingcar(refertovolumestudy)（流动车法）Carfollowing(platoon）（跟车法）LicensePlate道路名称__________起点__________终点__________调查日期__________调查员__________天气__________

序号车辆类型起点时间T1终点时间T2行程时间ΔT=T2-T1区间车速V=L/ΔT1

2

┇

n

CarFollowingMethod道路名称__________起终点__________调查日期__________调查员__________天气__________路段编号观测时间减速次数以及原因中途停车最终断面时间行人自行车会车转向车公交停靠其他原因停止时间起动时间1

2

┇

n

Example3-13-3DensityStudy（交通密度调查）DensityThenumberofvehiclespresentonagivenlengthoflaneorroadway.(单位长度车道上，某一瞬时所存在的车辆数)Highdensitiesindicatethatindividualvehiclesareveryclosetogether,whilelowdensitiesimplygreaterdistancesbetweenvehicles.Headway,spacing,gap,andclearanceareallvariousmeasuresfordescribingthespacebetweenvehicles.DensityStudyMethods:input-output（出入量法）,photography（摄影）DensityStudyTechniqueInput-outputMethod（出入量法）Attimet0,thenumberofvehiclesisE(t0).Attimet,thenumberofvehiclespassingAandBareQA(t)andQB(t).Then,attimet,E(t)=QA(t)-QB(t)+E(t0)Thedensityis:K(t)=E(t1)/LABInput-outputMethodApproachtoobtainE(t0)LicenseplatePhotographTestcar(测试车法)ThetestcarstartsfrompointAatt0,andarriveatpointBatt1.Thenumberofvehiclespassedbyandpassingthetestcarareaandb.ThenumberofvehiclespassingpointBisq.

E(t0)=q+a-bInput-outputMethodTechniqueFreewayssegmentswithoutmerging(合流)ordiverging(分流)Thesegmentislongerthan800m,withtraveltimelongerthan5minutes.NeedtorecordthenumberofvehiclespassingthestartandendofthesegmentsNeedtorecordthenumberofvehiclesovertakingandovertakenbythetestcar.Pros

andConsoftheInput-outputTechniquePros（优点）SimpleintermsofmethodandmeasuringdevicesCanbeusedforvarioustrafficconditionsAccurateandeffectiveCons（缺点）Theerrorofcountingthenumberofvehiclespassingthestart(A)andend(B)pointsincreaseswithtime.(moreobservations).Photography(abovetheGround)Method（地面上摄影观察法）

K:Density

L:Lengthofthesegment

n:thenumberofphotosduringtimeperiodT

Ki:thenumberofvehiclesinthei-thphoto.Lusuallyfallsbetween50and100m.Multiplecamerasrequiredforlongsegments.AerialPhotography（航空摄影）Photostakenfromfixed-wingaircrafts,helicopters,balloons,…Usethesameequationasthepreviousmethodtocalculatedensity.ProsandConsPros:mostaccurateCons:expensive;notsuitablefortunnelsandbridges.Occupancy（占有率）DensityisdifficulttomeasureOccupancyisoftenmeasuredbydetectorsDefinedastheproportionoftimeadetectoris“occupied”(时间占有率)Alsotermed“laneoccupancy”TimeofOccupancyLVLDtoPulsesTimevi==lengthofvehicle+lengthofsensortimeofoccupancyLV+LDtomsecLD:lengthofthedetectorzoneSpaceofOccupancyTheproportionofspaceoccupiedbyvehicles(空间占有率）补充：RelationshipbetweenDensityandOccupancyLv:AveragevehiclelengthLD:lengthofthedetectorzoneMeasurefromaspecificdetectorinalaneUnit:vehiclesperkmperlane补充：ImageProcessingTechnology（视频检测技术）InserttheimageprocessingvideoNeedtoconvertfileformatParametersDetected:

Speed,occupancy,classification,gap,volumeHomeworkAssignment复习思考题3-2习题3-13-4DelayStudy（行车延误调查）TypesandDefinitionsofTrafficDelayDelay

Delaysareoftenusedtomeasuretheperformanceoftrafficflowatintersections.FixedDelay（固定延误）Thetimelostcausedbytrafficcontroldevicesandenvironmentrather

thanvehicles.StoppedTimeDelay（停车延误）Thetimeavehicleisstoppedwhilewaitingtopassthroughtheintersection.TypesandDefinitionsofTrafficDelayTravel-timeDelay（行驶延误）Thedifferencebetweenthedriver’sdesiredtotaltimetotraversetheintersectionandtheactualtimerequiredtotraverseit.Time-in-queueDelay（排队延误）Thetotaltimefromavehiclejoininganintersectionqueuetoitsdischargeacrossthestop-lineorcurb-line.TypesandDefinitionsofTrafficDelayApproachDelay（引道延误）Notonlyincludesstoppedtime,butalsoincludesthetimelostwhenavehicledeceleratesfromitsambientspeedtoastop,aswellaswhileacceleratingfromthestopbacktoitsambientspeed.FactorsAffectingTrafficDelayDriverVehicleRoadwayPercentageofTurningVehiclesVolume-Capacity(V/C)RatioLevelofServiceTrafficControlEnvironmentApplicationsofDelayDataEvaluatetheDegreeofTrafficCongestionGrasptheTrendofDelayAnalysisLevelofServiceBasisforRoadwayRehabilitation（改建）TransportationPlanningEconomicAnalysisBefore-afterStudyTrafficManagementDelay

StudyTechniquesCar-followingMethod（跟车法）Conductedalongwithtraveltimestudytoobtaininformationontraveltime,runningspeed,overallspeed,anddelay.Usuallyusedtoconducttraveltimeanddelaystudiesforpublictransportation.SheetforrecordingTravelTimeandDelayDelay

StudyTechniquesInput-outputMethod（输入-输出法）Usedfordelaystudyofbottlenecks（瓶颈路段）Recordtheamountofvehiclesenteringandexitingthebottlenecksegmentevery5minor15min.时间到达离去阻塞情况到达累计离去累计4:00-4:1580808080无阻塞4:16-4:3010018090170阻塞开始4:31-4:4512030090260阻塞4:46-5:009039090350阻塞5:00-5:157046090440阻塞消散5:16-5:307053090530阻塞结束Table3-8:Developmentanddissolutionoftrafficqueue.Trafficdelayofthe300thvehicle?Capacity=360vhe/hrTotalDelay=AreaIntersectionDelayStudyLocationswithtrafficcongestionTime:peakoroff-peakhourSampleSizeAtleast30/50vehiclesUseEquation3-16or3-17todeterminethepreliminarysamplesize.Needstobeconfirmedaftercollectingdata.IntersectionDelayStudyPointSamplingMethod（点样本法）Manualcountmethod(proposedbyUniv.ofBerkeley,1954)Toobtainqueuetime（排队时间）onintersectionapproaches（引道）3

to4observersandastopwatchOneobservernotifiesotherevery15seconds(mayuseotherintervalslike20s)ThesecondonecountsthenumberofstoppedvehiclesThethirdonecountsstop-and-govehiclesandthosewithoutstopping交叉口________引道________车道________调查日期________天气________观测员________观测时间在下列时间内停在引道内的车辆数引道交通量+0s+15s+30s+45s停驶车数非停驶车数

合计

EquationsTotalDelayAveragedelayforstoppedvehiclesAveragedelayforallvehiclesPercentageofstoppedvehiclesAllowableerrorExample3-2开始时间停过的车辆数引道交通量015s30s45s停止车辆数不停止车辆数17：00027911617：01400361417：0291614618017：031491317017：045002417小计192230335637ProsandConsofPointSamplingMethodProsAnindividualerrordoesnotaffectresultssignificantlyDoesnotrelyontrafficsignalComprehensiveresultsdescribingdelayatintersectionsConsNotappropriatewhenthepercentageofstoppedvehiclesisveryhigh(e.g.,nearly100%)Forapproacheswithmulti-lanes,needmoreobserversForsinglelaneapproach,notabletodistinguishdelayfordifferenttypesofmovements(TH,LT,RT)Hasresultonaveragedelay,whilenoinformationonthedistributionofdelay.3-5CapacityStudy（通行能力调查）CapacityStudyRoadwaySegmentHeadwayStudyHeadwayofplatoonsHeadwayfordifferentvehicletypesPassengercarequivalence（换算成当量小车）IntersectionGapStudyLeftturningvehiclesCapacityStudyIntersectionSaturationFlowRate（饱和流率）Assumethatanintersection’sapproachsignalweretostaygreenforanentirehour,andthetrafficwasasdenseascouldreasonablybeexpected.Thenumberofvehiclesthatwouldpassthroughtheintersectionduringthathouristhesaturationflowrate.SaturationFlow（饱和流量）Themaximumnumberofvehiclespassingtheapproachoraconflictpointduringagreeninterval.（在一次绿灯时间内，进口道或冲突点上连续车队能通过停车线或冲突点的最大流量）CapacityStudySaturationheadway（饱和车头时距）Example3-4(车头时距方法）SaturationHeadway3-6Origin-Destination(OD)Study（起讫点调查）DefinitionsTrip（出行）BasicunitoftravelbehaviorTripinvolvesmovementfromasingleorigintoasingledestination.Describedintermsoforigins,destinations,purposes,timesofoccurrence,travelmodes,androutes.Eachtriphasasingleoriginandasingledestination;hascertainpurpose(s);usesoneormoretrafficmodes.DefinitionsTrip（出行）Residenttrip（居民出行）Eachtripmustbemadeviahighwaysorurbanroads.Traveltimeshouldbelongerthan5min.Tripswithbicyclingshouldbelongerthan400m.Tripstakenbywalkingorbicyclingusethestartpointastheoriginandthefurthermostpointasthedestination.DefinitionsTripEnds（出行端点）OriginanddestinationThenumberofnodesistwicethenumberoftripsInternalTrip（境内出行）TripsmadewithinthestudyareaExternal(Through)Trip（过境出行）TripspassingthroughthestudyareaDefinitionsInter-zonalTrip（区间出行）OriginanddestinationindifferentzonesIntra-zonalTrip（区内出行）OriginanddestinationwithinthesamezoneCentroid（小区形心）CenteroftripsinazoneExpectationLine（期望线）LineconnectingcentroidsWidthofthelinerepresentingtheamountoftripsDefinitionsMajorDirectionalExpectationLine（综合期望线、主流倾向线）Themergeofclosedexpectationlinesforbetterpresentation（seefigureinnextslide)CordonLine（调查区域境界线）AnimaginaryboundaryaroundastudyareaofinterestEstablishedtodefineaCBDorothermajoractivitycenterDefinitionsScreenLine（分隔核查线）Someformofnaturalorman-madebarrieracrosswhichtherearealimitednumberofcrossingpointsDefinitionsTripProduction（出行产生）Home-basedtrips:Movementassociatedwiththehomeendofatripiscalledtripproduction,whetherthetripisleavingorcomingtothehome.Non-home-basedtrips:theoriginofatripTripAttraction（出行吸引）Home-basedtrips:thehomeendofatripNon-home-basedtrips:thedestinationofatripTripDistribution（出行分布,O-D交通量）AmatrixthatdisplaysthenumberoftripsgoingfromeachorigintoeachdestinationDefinitionsODTablePurposesofODStudy(Survey)ODstudiesareconductedtounderstandthepatternofthemovementofpersonsandgoodsinaparticularareaofinterestduringaparticularperiodoftime.ODstudiesaretypicallyconductedinordertocollectdataasabasisfortraveldemandmodeling.Oncedemandmodelsarecreated:analysisoftravelcharacteristics,e.g.,traveltime,delay,pollutiontheimpactofmodificationorclosure(duetoanincidentorroadwork)ofexistingroutesthedesignandevaluationoftheeffectivenessofnewroutesontheexistingtransportationnetworkusedtomakelongrangetravelforecaststoidentifypotentialfutureproblemsinthetransportationnetworkandevaluatealternativesolutionsTypesofOD

StudyPersonTrip（个人出行）ResidentialtripsSurveyincludestrippurposes,travelmodes,timesofoccurrence,tripdistance,OandD,andfacilities(landuse)VehicleTravel（车辆出行）VehiclesincludetrucksandbusesSurveyincludestypesofvehicles,load,purposes,numberoftrips,startingandarrivingtime,OandD,etc.GoodsMovement（货物流通出行）Dispatchcenter,parkinglocation,storage,etc.Typesofgoods,carloadings（运入运出量）,etc.ODDataCollectionMethodsHomeInterviewSurvey（家访调查，个人出行）RoadsideInterviewSurvey（路边询问调查）PaperSurvey（发表调查，车辆出行）PostcardMailback（明信片法）WorkTripSurvey（工作出行调查）LicensePlate（车辆牌照调查）ODDataCollectionMethodsBusStationorOn-boardSurvey（ontransitvehicles)（公交站点调查）FillingSurveyForms(bythosepurchasingIC