StudyonLeft-turnProhibitionMeasuresWarrantsat

UnsignalizedIntersectionsF.LZHANGS.M.FENGY.S.CIThe6thAdvancedForumonTransportationofChina(AFTC’2010)Introduction√Trafficoperationimpacts√Safetyevaluation√Impactsofindirectleft-turntrafficondrivingbehaviors

Left-turnprohibitionmeasures:

Installationwarrants???Notforbiddenturningleft

ButfindotherwaysNoleft-turnprohibitionOneleft-turndirectionforbiddenConflictCharacteristicsAnalysis16conflictpoints12conflictpointsConflictcharacteristicsofleft-turntraffic:Twoleft-turndirectionsforbiddenAllleft-turndirectionsforbiddenConflictCharacteristicsAnalysis8conflictpoints4conflictpointsTrafficOrganizationMethodsa)Right-turnafterstraight-goingb)Straight-goingafterright-turnLeft-turntrafficturningmovements:U-type●Reduceconflictpoints●Improveintersectioncapacity●Increase

traveltimeTrafficOrganizationMethodsc)P-type●Reduceconflictpoints●Longertraveldistances●Distancebelow200md)Detourinadvance●Decreaseconflictpoints●Influenceadjacentroadnetwork●Distancebelow500m●LongertraveltimeInstallationWarrantsConflictpointsbeforesettingleft-turnprohibitionmeasuresAssumption：

Totalconflictpoints：(1),i=1,2,3,4;j=L,S,R;Conflictpointsofanyflow：(2)(3)Kisalogicalvariable

InstallationWarrantsConflictpointsaftersettingleft-turnprohibitionmeasuresTotalconflictpoints：Conflictpointsofanyflow：Intersectionbenefit：(4)(5)(6)is

the

conversioncoefficientis

the

traveltime;CaseStudyTrafficvolumeandvehicles’operatingdirectionsoftheintersectionExperimentResultsDetourtypeConflictpointsvariablequantityOneleft-turndirectionisforbiddenTwoleft-turndirectionsareforbiddenAllleft-turndirectionsareforbiddenEntrance1Entrance2Entrance3Entrance4Entrance1、3Entrance2、4Entrance

1、2、3、4R-turnafterS-going-10-450-140-400-420-280370S-goingafterR-turn80-90380-60220-280370P-type10904501160600174014303810Detourinadvance813510124766718209873237

Intersectionbenefitaftersettingleft-turnprohibitionmeasuresTheEndWedefinetheintersectionconflictpointsasthesumofthetwomergingtrafficflowsandestablishtheinter-sectionconflictpointcalculationmodel.Wemaketheintersectionbenefitasabasiswhichcanbeusedtojustifyleft-turnprohibitionmeasures.Iftheconflictpointsincreaseaftertakingleft-turnprohibitionmeasures,itissuitable;otherwise,itisnot.Anexampleispresentedtoverifytheeffectivenessofleft-turnprohibitionmea