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

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<ul><li><p>JaeyoungLee,Ph.D.,MohamedAbdel-Aty,Ph.D.,andLingWang,Ph.D. 8/20/2016</p><p>UtilizingMicroSimulationtoEvaluatetheSafetyandEfficiencyoftheExpresswaySystem</p><p>Overview</p><p>Thisprojectanalyzedthesafetyofthreeexpresswaysbasedonaveragedailytraffic,averagehourlytraffic,andmicroscopictrafficdataatfive-minuteintervals.Themodelingresultsshowedthatweavingsegmentshadexperiencedmorecrashesthanothersegmenttypes.</p><p>Thecrashmechanismsofweavingsegmentswereexploredusingreal-timecrashanalysis.Then,activetrafficmanagement(ATM)strategies,</p><p>rampmetering(RM)andvariablespeedlimit(VSL),wereidentifiedtobepotentialcountermeasurestoimprovethesafetyofweavingsegments.Subsequently,awell-calibratedandvalidatedmicroscopicsimulationnetworkwasbuiltforacongestedweavingsegment.ThesimulationresultsverifiedthatATMcansignificantlyimprovethetrafficsafetyofthestudiedweavingsegments.</p><p>Figure1.Averagecrashrateforthreestudiedexpressways</p><p>(crashesperhourspersegment)</p><p>Figure2.StudysubjectofVISSIMsimulation</p></li><li><p>JaeyoungLee,Ph.D.,MohamedAbdel-Aty,Ph.D.,andLingWang,Ph.D. </p><p>StudyTasks</p><p>1) IdentifyingthemostdangerousexpresswaysegmenttypebasedonsafetyanalysesusingADT,AHT,andmicroscopictrafficdata;2) Exploringthecrashmechanismofthemostdangerousexpresswaysegmenttypeusingthereal-timesafetyanalysis;3) Buildingawell-calibratedandvalidatedVISSIMnetworkforanexpresswaysegmentthathashighcrashpotential;and4) TestingtheimpactofATMonthesafetyoftheexpresswaysegmentidentifiedbyTask3.ConclusionsandRecommendations</p><p>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.</p><p>Oncecrashmechanismshavebeenidentifiedusingreal-timesafetyanalyses,microscopicsimulationcanbeusedtotestandverifytheimpactofactivetrafficmanagementonthesafetyofexpresswaysegments.</p><p>Figure3.Weavingsegmentmicrosimulationnetwork</p></li></ul>