Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D., and ?· Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D.,… page 1
Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D., and ?· Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D.,… page 2

Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D., and ?· Jaeyoung Lee, Ph.D., Mohamed Abdel-Aty, Ph.D.,…

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  • JaeyoungLee,Ph.D.,MohamedAbdel-Aty,Ph.D.,andLingWang,Ph.D. 8/20/2016

    UtilizingMicroSimulationtoEvaluatetheSafetyandEfficiencyoftheExpresswaySystem

    Overview

    Thisprojectanalyzedthesafetyofthreeexpresswaysbasedonaveragedailytraffic,averagehourlytraffic,andmicroscopictrafficdataatfive-minuteintervals.Themodelingresultsshowedthatweavingsegmentshadexperiencedmorecrashesthanothersegmenttypes.

    Thecrashmechanismsofweavingsegmentswereexploredusingreal-timecrashanalysis.Then,activetrafficmanagement(ATM)strategies,

    rampmetering(RM)andvariablespeedlimit(VSL),wereidentifiedtobepotentialcountermeasurestoimprovethesafetyofweavingsegments.Subsequently,awell-calibratedandvalidatedmicroscopicsimulationnetworkwasbuiltforacongestedweavingsegment.ThesimulationresultsverifiedthatATMcansignificantlyimprovethetrafficsafetyofthestudiedweavingsegments.

    Figure1.Averagecrashrateforthreestudiedexpressways

    (crashesperhourspersegment)

    Figure2.StudysubjectofVISSIMsimulation

  • JaeyoungLee,Ph.D.,MohamedAbdel-Aty,Ph.D.,andLingWang,Ph.D.

    StudyTasks

    1) IdentifyingthemostdangerousexpresswaysegmenttypebasedonsafetyanalysesusingADT,AHT,andmicroscopictrafficdata;2) Exploringthecrashmechanismofthemostdangerousexpresswaysegmenttypeusingthereal-timesafetyanalysis;3) Buildingawell-calibratedandvalidatedVISSIMnetworkforanexpresswaysegmentthathashighcrashpotential;and4) TestingtheimpactofATMonthesafetyoftheexpresswaysegmentidentifiedbyTask3.ConclusionsandRecommendations

    1) InADT-based,AHT-based,andmicroscopic-traffic-basedsafetystudies,allresultsillustratedthattheexistenceofaweavingsegmentcouldincreasecrashpotential;2) Themicroscopictraffic(five-minuteintervals)dataisthemostsuitabletrafficdataifATMisusedtoimprovethesafetyofasegmentinrealtime;3) Themaincrashcontributingfactorsforweavingsegmentsarespeeddifferencebetweenthebeginningandendofweavingsegmentsandweavinginfluencelength.Bothfactorshavepositiveimpactoncrashrisk;4) Throughmicroscopicsimulation,ATMstrategiesimprovedthesafetyofacongestedweavingsegmentbyreducingcrashoddsratiobecausetheyreducedthespeeddifferenceorweavinginfluencelengthorboth;5) TheproposednewRM,whichtookbothtrafficoperationandsafetyintoconsideration,wasbetterthantraditionalRMbecauseitprovidedsafertraffic;and6) Theintegratedstrategy(RM-VSL)producedlowerconflictnumbersthanRMalonewhenon-rampqueuelengthwascontrolled.

    Oncecrashmechanismshavebeenidentifiedusingreal-timesafetyanalyses,microscopicsimulationcanbeusedtotestandverifytheimpactofactivetrafficmanagementonthesafetyofexpresswaysegments.

    Figure3.Weavingsegmentmicrosimulationnetwork