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UrbanSim:ModelingUrbanDevelopmentforLandUse,TransportationandEnvironmentalPlanningPaulWaddellDepartmentofUrbanDesignandPlanningandDanielJ.EvansSchoolofPublicAffairsUniversityofWashingtonBox353055Seattle,WA98195pwaddell@u.washington.eduWaddell1UrbanSim:ModelingUrbanDevelopmentforLandUse,TransportationandEnvironmentalPlanningAbstractMetropolitanareashavecomeunderintensepressuretorespondtofederalmandatestolinkplanningoflanduse,transportation,andenvironmentalquality;andfromcitizenconcernsaboutmanagingthesideeffectsofgrowthsuchassprawl,congestion,housingaffordability,andlossofopenspace.TheplanningmodelsusedbyMetropolitanPlanningOrganizations(MPOs)weregenerallynotdesignedtoaddressthesequestions,creatingagapintheabilityofplannerstosystematicallyassesstheseissues.UrbanSimisanewmodelsystemthathasbeendevelopedtorespondtotheseemergingrequirements,andhasnowbeenappliedinthreemetropolitanareas.ThispaperdescribesthemodelsystemanditsapplicationtoEugene-Springfield,Oregon.IntroductionTherelationshipsbetweenlanduse,transportation,andtheenvironmentareattheheartofgrowthmanagement.Theemergingconcernthatconstructionofnewsuburbanhighwaysinducesadditionaltravel,vehicleemissions,andlanddevelopment,makingitimplausibleto‘buildourwayout’ofcongestion,hasreshapedthepolicycontextformetropolitantransportationplanning(Downs,1992).Recognizingtheeffectsoftransportationonlanduseandtheenvironment,theCleanAirActAmendmentsof1990,the1991IntermodalSurfaceTransportationEfficiencyAct(ISTEA)mandatedthatMPOsintegratemetropolitanlanduseandtransportationplanning.Theselegislativeactionshaveledtosubsequentlegalchallengestothetraditionalapproachtotransportationplanningthatignoresthesefeedbackeffects(GarretandWachs,1996).ThepassageoftheTransportationEquityActforthe21stCentury(TEA21)in1998,asthesuccessortoISTEA,softenedtheseplanningrequirementssomewhat,butsignificantpressureremainstobettercoordinatemetropolitanplanningoflanduse,transportation,andtheenvironment.Requirementsforimprovedandbetterintegratedlanduseandtransportationmodelshaveemergednotonlyinresponsetothisfederallegislation,butalsofromstategrowthmanagementprogramsthatpromotecloserlinkageoflanduseandtransportationplanning.Pressureforchangehasalsocomefromthecommunityofpracticingandacademicplannersandadvocatesfortheenvironmentandalternativemodesoftransportationthathavebecomefrustratedwiththestateofthepractice,asexemplifiedinthePortlandLUTRAQproject(Blizzard,1996).Inresponsetothegrowingconcernregardingthelimitationsofcurrentlanduseandtransportationmodels,theTravelmodelImprovementProject(TMIP)wasformedasacollaborativeeffortbytheFederalHighwayAdministration,theFederalTransitAdministrationandtheEnvironmentalProtectionAgency.In1995,TMIPhostedaninternationalconferenceonlandusemodelingtoconvenepractitioners,researchers,andconsultants,toassessthestateofthepracticeandtomakerecommendationsfornewmodeldevelopmenttoaddresslimitationsinthecurrentpractice.Recommendationsputforwardatthisconferenceincludedmovingfairlyquicklytowardrandomutility-basedmodels;usingaclearbehavioralbasisdescribingtheprincipalactorsandchoicesinvolvedinurbandevelopmentandtransportation;placinggreateremphasisontheuseofmodelsforpolicyanalysis,planning,andsensitivitytesting;recognizingthevaryingtemporalandgeographicscalesrelevanttodifferentprocessesinurbandevelopment;movingtodisaggregatemodelsanddata;drawingonmultipleWaddell2disciplines;developingmodularmodels;increaseduseofGISandRemoteSensing;andtestingtheeffectsoftransportationonlanduse(Weatherby,1995).FederaleffortstoimprovethestateofthepracticethroughtheTMIPprogramhavefocusedalmostexclusivelyonlong-terminvestmentinaresearchanddevelopmenteffortforanewtrafficmicrosimulationmodel,calledTRANSIMS,andhavenotyetmadeanyinvestmentinnewlandusemodelingapproaches.Asaresult,theinitiativefordevelopingnewlandusemodelshasbeentakenupatthestateandlocallevel.EffortssuchastheOregonDepartmentofTransportation’sTransportationandLandUseModelIntegrationProject(TLUMIP),theStateofUtah’sQualityGrowthEnhancementTools(QGET)andEnvisionUtahefforts,theOahuMetropolitanPlanningOrganization’sinvestmentsinnewlanduseandtransportationmodels,amongothers,areleadingtheway.WithintheOregongrowthmanagementcontext,theOregonDepartmentofTransportationlaunchedanambitiouseffortin1996todevelopnewintegratedmodelstoevaluatetheinteractionsbetweentransportationandlanduse.TheTLUMIPefforthadtwocomponents.Thefirstwastheimplementationofastatewidelanduseandtransportationmodel,forwhichtheTRANUSmodel(delaBarra,1989)wasadopted.ThesecondcomponentofTLUMIPwasthedevelopmentofUrbanSim,anewmetropolitan-scalelandusemodelforintegrationwithtransportationmodels.UrbanSimwasdesignedspecificallytoaddressthepolicyanalysisrequirementsofmetropolitangrowthmanagement,withparticularemphasisonlanduseandtransportationinteractions.TheOregonTLUMIPeffortextendedtheoriginalUrbanSimdesigndevelopedforHonolulu,Hawaii,andimplementedaprototypeversionintheEugene-Springfieldmetropolitanarea.TestingofthecurrentversionofthemodelintheEugene-Springfieldareausingdatafrom1980to1994hasprovide