An Evaluation of Signalized Intersection System An

AnEvaluationofSignalizedIntersectionSystemAnalysisTechniquesWalterJ.Freeman,P.E.,KienY.Ho,P.E.,ElizabethA.McChesney,E.I.T.Asystemofsignalizedintersectionsisacriticalelementinthesmoothoperationofbotharterialandurbanstreetfacilities.Theamountofvehicularandpedestriantrafficwhichcanbeprocessedbyasystemofintersectionsdependona)characteristicsofthetrafficandpedestrianstream,b)trafficcontrolmeasures,c)variousphysicalandoperatingcharacteristicsoftheroadwayandd)theenvironmentalconditionswhichhaveabearingontheexperienceandactionsofthedriver.Becausemanysuchfactorsinfluenceinterruptedflowthroughasystemofintersections,itisimportantthatthebesttechniquebeutilizedforanalyzingasystemofintersections.Asystemofsignalizedintersectionsisdefinedastwoormoresignalizedintersectionsthatarecloselyspaced(under1500’)together.Intersectionsystemsnotonlycontrol,toalargeextent,thecapabilityofmajorandsecondaryarterialstreetstoaccommodatetheflowoftrafficandpedestriansinanurbanarea,buttheyalsomayseriouslyaffectorlimittheabilityofnearbyfreewaystoperformatmaximumefficiency.Thesystemofsignalizedintersectionsselectedforthisstudyprovideanidealrepresentationofthisoperationalscenario.Todaythereisavarietyofengineeringanalysistools/software’savailabletoanalyzeandmodelanexistingorproposedsignalizedintersectionsystem.Whilethemajorityoftheanalysistoolsprovidetheengineerwithvaluableinformationpertainingtointersectionsystemdelays,queuelength,saturationflow,levelsofservice,etc,thereisnotasingleanalysissoftwarethatcouldaccuratelypredictallthisvaluableinformationforanactualorproposedfieldcondition.Forexample,whensignalizedintersectionsarecloselyspaced,somesoftwareanalysistechniquesaregoodatpredictingdelaysonlyandweakatpredictingothervaluableinformationsuchasqueuelengthorqueuespillback.Thepurposeofthisreportistoevaluatetechniquesforthedesignandanalysisofasystemofsignalizedintersections.Asacasestudy,agridsystemofeightsignalizedintersectionslocatedindowntownBostonwaschosenforthisreport.Theseeightcloselyspacedintersections,provideanidealconditionfortestinganalysistool’sabilitytopredictalltheavailableinformationrelatedtodelays,queuelength,saturationflowratesandothermeasuresofeffectiveness.Thisreportcomparesseveralanalysistechniquesandtheirpredictedandobservedresultsfortheeightobservednetworkintersections.Evaluationincludestestinghowwellthesetechniquespredictdelays,queuelengths,queuespillbackandlevelsofservice.Inaddition,sensitivityanalysesareperformedtoevaluatethelimitationsofthesetechniques.Finally,thereportwilldeterminehowefficientlyeachanalysistechniqueperformedonthesignalizedintersectionsystem.Inaddition,thereportshallspellouttherequirementsforanacceptabletechniquetoaidinthedesignandevaluationofsignalizedintersectionsystems.LITERATUREREVIEWThehistoryofsignalizedintersectionsystemanalysistechniquesisaddressedinthisreview.Adetailedliteraturesearchrevealedthatsignalizedintersectionscapacityhavebeensubjectedtoagreatdealofstudysincethemid1950’s.Theprocedures/techniquesforthedesignandanalysisofsignalizedintersectionsaretabulatedasfollows:SoftwareSoftware’sFunctionTypesofFacility1.HCS–HighwayCapacitySoftwareRelease3.0Computesintersectioncapacity,delaysandlevelofservice(LOS)basedontheHighwayCapacityManual.Developedforanalyzingisolatedintersections.Theintersectionsmaybesignalizedorcontrolledbytwo-wayorallwaystopsigns.Applyingarrivaladjustmentfactorstointerconnectedlanegroupsmayapproximateprogression.2.PASSERIIAnalyzesarterialprogressiononly.Optimizeandsimulateonlythemainlinearterialandignoresthesidestreets.Optimizecyclelength,splitsandoffsets.Providebandwidths,time-spacediagram,efficiencyattainability,fuelconsumptionandspeedprogression.Developedforanalyzingarterialprogression.3.PASSERIIIAnalyzessignalizeddiamondinterchangesonly.Computessignaltimingcoordinationforthesignalizedinterchange.Optimizesoffsetandsplits.Developedforanalyzingsignalizeddiamondinterchanges.4.PASSERIVAnalyzesanetworkofsignalizedintersectionsandbasedonprogressionbandwidthoptimizationalsobasedonMAXBAND.Developedforanetworkofmorethanonearterialwherebandwidthoptimizationisthemaingoal.Italsocomputesthecyclelengthandgreensplitbutnotphasing.SoftwareSoftware’sFunctionTypesofFacility5.SYNCHROAnalyzesandoptimizesanetworkofsignalizedintersections.Itprovidesadetailedsummaryreportoncapacity,levelofservice,lanes,volumes,timing,queuelengths,blockingproblems,delay,stopandfuelconsumption.Developedforanalyzingandsimulatinganetwork/gridofsignalizedintersections.6.SimTrafficAnalyzesandsimulatesanetwork/gridofsignalizedandunsignalizedintersections.ItprovidesresultontheamountofMOEssuchasdelay,stops,queues,averagespeed,fuelconsumption,andthroughput.SimTrafficmodelsintersectiontrafficthroughputbasedoncarfollowingformulas,accelerationrates,decelerationrates,reactiontoyellowlight,reactiontimes,gapacceptance,cruisespeed,turningspeedandvehicledriverperformancecharacteristics.Developedforanalyzingandsimulatinganetwork/gridofsignalizedandunsignalizedintersection.7.SIDRAAnalyzessignalizedandunsignalizedintersectionsandroundabouts