A report by the University of Vermont Transportation Research Center
Vermont Statewide Travel Demand Model – A Preliminary Evaluation
Report #10-007 | May 2010
VermontStatewideTravelDemandModel–APreliminaryEvaluation
VermontAgencyofTransportation
May2009
Preparedby:AndrewWeeks
TransportationResearchCenterFarrellHall210ColchesterAvenueBurlington,VT05405Phone:(802)656‐1312Website:www.uvm.edu/trc
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
ii
Acknowledgements
TheProjectTeamwouldliketothanktheVermontAgencyofTransportation,theChittendenCountyMPO,andStephenLaweatResourceSystemsGroup,Inc.fortheirtimeandinsightsduringthepreparationofthisreport.
Disclaimer
Thecontentsofthisreportreflecttheviewsoftheauthors,whoareresponsibleforthefactsandtheaccuracyofthedatapresentedherein.ThecontentsdonotnecessarilyreflecttheofficialvieworpoliciesoftheUniversityofVermontTransportationResearchCenter.Thisreportdoesnotconstituteastandard,specification,orregulation.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
iii
TableofContents
ListofTables.....................................................................................................................................iv
ListofFigures ...................................................................................................................................iv
ExecutiveSummary.......................................................................................................................... 1
1. Introduction ................................................................................................................................ 3
2. Background ................................................................................................................................. 3
3. ReviewofModelingPractices ..................................................................................................... 4
3.1 StatewideModelingatOtherDepartmentsofTransportation ............................................ 4
3.2 AdvancesinTravelDemandModeling ................................................................................. 6
3.3 OngoingApplicationsofTransportationModeling ............................................................. 7
4. StatewideTravelDemandModelingattheVermontAgencyofTransportation ....................... 8
4.1 ModelStructureandComponents ........................................................................................ 8
4.2 Application,ImprovementandMaintenanceoftheModel ............................................... 12
5. OptionsfortheStatewideModelandModelingProgram ....................................................... 19
5.1 FourOptions ....................................................................................................................... 19
5.2 OptionsandModelStrengthsandWeaknesses ................................................................. 25
6. TravelDemandModelingSoftwarePackages........................................................................... 25
6.1 Cube/Voyager ..................................................................................................................... 26
6.2 TransCAD ............................................................................................................................ 27
6.3 VISUM ................................................................................................................................. 29
6.4 PractitionerExperiences ..................................................................................................... 29
7. PreliminarySummaryandRecommendations.......................................................................... 30
References ..................................................................................................................................... 32
AppendixA ..................................................................................................................................... 35
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
iv
ListofTables
TABLE1:STATUSOFSTATEWIDEMODELINGCAPABILITY‐SPRING2005....................................... 5TABLE2:OPTIONSSUMMARY........................................................................................................ 19
TABLE3:MODELSTRENGTHS&WEAKNESSWITHRELEVANTOPTIONS ....................................... 25TABLE4:SUMMARYOFCUBE,TRANSCAD,ANDVISUMFEATURESANDFUNCTIONALITY ........... 28
ListofFigures
FIGURE1:DAILYPERSONTRIPRATESPERHOUSEHOLDBYPURPOSE............................................. 9FIGURE2:TRIPLENGTHFREQUENCYDISTRIBUTION ..................................................................... 10FIGURE3:MODELTRAFFICANALYSISZONES................................................................................. 11
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
1
ExecutiveSummary
TheUniversityofVermontTransportationResearchCenter,workingwiththeVermontAgencyofTransportation,isconductinganevaluationoftheexistingstatewidetraveldemandmodeland
toidentifypotentialimprovementsandrefinementstothemodelbasedonplanningpracticesandneeds.Themodel’scurrentsoftwareplatform,Cube/Voyager,isalsoexplored,withacomparisontotwootherwidely‐usedmodelingsoftwarepackages.Theevaluationalsoincludes
aliteraturereviewofstatewidetraveldemandmodelingpracticesinotherstates,includinggeneralmodelstructure,uses,andmodeloperationandmaintenance,aswellasadiscussionofemergingtrendsintraveldemandmodeling.
TheVermontAgencyofTransportationhasoperatedastatewidemodelingprogramfornearly
fifteenyears,beginninginthemid‐1990susingTRANPLANtransportationplanningsoftwareandGISmethods,tothecurrentmodelinCube/Voyager.Thestatewidemodel,whichcoverstheentiregeographicareaofVermontandthousandsofmilesofroadway,hasservedandcontinues
toserveasavaluabletoolthatprovidestravelactivitydataprojectionsfortransportationplanningstudiesandanalysesthroughoutthestate.Thedataprovidedbythemodelisusedbyplannersanddecisionmakerssothatsoundtransportationpoliciescanbedeveloped.
Withthedevelopmentandmanagementoftransportationsystemscontinuingasavitalroleof
theVermontAgencyofTransportationandotherinvestedstateagencies,includingtheplanningofhighways,transit,freightandevaluationsoftheirimpactonsocietyandtheenvironment,the
statewidemodelingprogramwillhaveongoingutilityandisavaluabletoolforVTrans.Thestatewidemodeldoeshavelimitations,however,infunctionalityanddegreeofutilityandreliabilityforpotentialprojectneeds.Importantly,themodelisnotcurrentlycapableof
modelingtransitorrailnetworks,sinceitsprimarytransportationsystemislimitedtohighwaysandotherroadways.
DependingontheidentifiedplanningandpolicyneedsoftheVermontAgencyofTransportationandotherparticipatingstateagenciesthatwouldrequireuseofthestatewidemodel,themodel
couldbenefitfromthefollowingimprovementsandrefinementsinthecomingyears:
Developmentofatransitnetwork(bus,rail,orboth)andafreightrailnetwork. Developmentofanewmodechoicemoduletocomplementanewtransitnetwork. Algorithmsfordisaggregationofvehiclemilesoftravel(byvehicleclass,averagespeed,
roadwaygrade,etc.)forairqualityanalyses. Feedbackloop(s)betweenmodelingsteps,suchasbetweentrafficassignmentandtrip
distribution.
Updatesofinputdata,inclusionofroadwaygradedata,andfurthercalibrationandvalidationofmodelalgorithms,assumptions,andoutputs.
Developmentofanactualyear2030scenariotocover20‐yearforecastsfromyear2010.
AdegreeofintegrationwiththeChittendenCountyMPO’sregionalmodel.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
2
Ataminimum,thereisenoughcausefortheVermontStatewideModeltobemaintainedandperiodicallyupdatedtokeepitviableandavailableforplanningneedsatVTrans.Theoverallmodelcouldbekeptinitscurrentformwithoutsubstantialimprovements,suchastransitand
railnetworks,butshouldremainavailableforforecastsofroadwaytravelandVMTestimates.Mostimportantly,thesuccessandlongevityofthestatewidemodelgreatlydependsontheclearly‐definedproceduresandgoalsofitsutilitybyVTransandotherVermontagencies.As
statedpreviously,thegoalsofastatewidemodelingprogramshouldbedefinedwellinadvanceofmodel‐specificdetails,suchasdataneeds,modelcomponents,computersoftware,andbudgetallocation.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
3
1. Introduction
TheUniversityofVermontTransportationResearchCenter,workingwiththeVermontAgencyofTransportation(VTrans),isconductinganevaluationoftheVermontstatewidetraveldemand
model’sutility,components,andcurrentsoftwareplatform.Thisreportrepresentsthefirstworkingdraftoftheevaluationanditspreliminaryfindings.Thegoalsoftheevaluationareto:
IdentifythecurrentandpotentialusesforthemodelbasedonVTransplanningpracticesandneeds.
Recommendupdatestothemodeltomeetfutureimplementation. Compareitsexistingsoftwareplatformwithtwootherwidely‐usedsoftwarepackages
currentlyavailable.
Alsoprovidedinthisreportarealiteraturereviewofstatewidetraveldemandmodeling
practicesinotherstates,includinggeneralmodelstructure,operation,andmaintenance,andadiscussionofemergingtrendsintraveldemandmodeling.
2. Background
TheVermontAgencyofTransportationisresponsiblefortheplanning,construction,
maintenance,andpolicygoverningthetransportationsystemintheStateofVermont.Thetransportationsystemincludespassengertravelbymodessuchasmotorvehicles,transit,air,andnon‐motorizedtravel,aswellasthemobilityoffreight.ThePolicyandPlanningDivisionof
VTrans,specifically,developsandoverseesthecomprehensivetransportationplanningstrategiesandpolicyframeworkinthestate,andworkswithlocalmunicipalities,theelevenregionalplanningcommissions(RPC),theChittendenCountyMetropolitanPlanningOrganization
(CCMPO),andotherstateagenciestoensurethatthestate’stransportationsystemispartofaresponsibleandefficientsocial,economical,andecologicaldevelopmentpolicyplan.
PartoftheVTransplanningresponsibilitiesincludestheforecastingoffuturetraveldemandandtravelpatternsonthetransportationsystem.Thepurposeoftheforecastsistohelpguidepolicy
andfundingdecisions,suchastheconstructionofanewroadway,thecreationofanewbustransitline,oralandusedevelopmentschemetomakemostefficientuseofthein‐placetransportationinfrastructure.Inordertoperformtheforecasts,andalsotogainbetter
understandingofthecurrenttransportationsystem,VTransreliesontransportationplanningtoolsforanumberofitsplanningtasks.Thesetransportationtoolsrangefromverysmall‐scale,detailedmodels,idealfortaskssuchasroadwaycapacityanalysesandmanagementoftraffic
operations,toalarge‐scale,statewideplanningmodel,idealfordeterminingthetraveldemandloadsontheentiremulti‐modaltransportationsystem.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
4
Foritsplanningresponsibilities,VTransreliesonthestatewidemodeltoevaluatetheeffectsoftransportationprojectsandtoguidefuturedevelopmentpoliciesforsectionsofthetransportationsystem.Thestatewidemodel–identifiedasatraveldemandmodel–coversthe
entireStateofVermontandincorporatesdemographicandeconomicdataofVermont’shouseholds,employmentestimates,andthecharacteristicsofthetransportationsystemitself,includingthetravelmodeopportunitiesandthestate’sroadwaynetworkintoastructuredfour‐
steptransportationplanningmodel.Essentially,thepassengertravelmodelestimatesdemandforuseofthetransportationsystembasedoncharacteristicsofthetransportationnetworkanditspotentialusers,andreportsmeasurabledegreesofuse,includingroadwayvolumes,milesof
travelonroadways,andtransitridership.Thestatewidemodelalsoincludesafreightdemandmodelthatestimatestruckusageofthestate’sroadwaynetworkforthemovementofgoods.
3. ReviewofModelingPractices
3.1 StatewideModelingatOtherDepartmentsofTransportation
Currently,approximatelyone‐halfofthestatesintheUnitedStateshavefunctionalstatewide
models(1).Thestructure,utility,andcostsofthenumerousstatewidemodelsvaryandgreatlydependontheneedsoftheirhostdepartmentsoftransportation.PublisheddocumentssuchasNCHRPSynthesis358:StatewideTravelForecastingModels(1)andStatewideTravelDemand
Modeling:APeerExchange(2)provideinformationaboutcurrentmodelingpracticesinstatesthroughoutthecountrybasedonsurveyresponsesfromstatedepartmentsoftransportation,includingVermont.Table1,takenfromNCHRPSynthesis358,page14,presentsasummaryof
statewidemodelingactivityasof2005.
AscitedinNCHRPSynthesis358,statespredominantlyusetraditionalfour‐stepproceduresatthecoreoftheirpassengertraveldemandmodels,similartourbanorregionalmodels.Tripgenerationisgenerallyperformedbycross‐classificationtechniques,tripratesandlinear
equations,ortour‐basedmultinomiallogitexpressions(1).Themostcommonlyuseddemographicandtraveldatasources,suchastheUSCensus,theCensusTransportationPlanningPackage(CTPP),theNationalHouseholdTravelSurvey(NHTS),andlocalMPOinformation
providereadilyavailabledataforusebystatesintheirmodels,andareusedsolelyorsupplementedbystate‐collecteddata.Furthermore,inmoststateswithfunctionalmodels,gravitymodelapplicationisusedfortripdistribution,whiletherearesomeinstancesofgrowth
factormethods.Modechoiceistypicallyaccomplishedbylogitexpressionsorfixedpercentageshares,andtrafficassignmentisperformedusingestimationsofequilibriumconditions(1).
Moreover,NCHRPSynthesis358findsthatstatedepartmentsoftransportationpredominantlyutilizetheirmodelsforcorridorplanning,systemplanning,bypassstudies,regionalplanning
whilecollaboratingwithanMPO,andproject‐levelforecasts,suchasforenvironmentalimpactpurposes.Approximatelyone‐thirdofstateswithfunctionalmodelsapplytheirmodelsforairqualityanalyses,freightplanning,andeconomicdevelopmentandlong‐terminvestmentstudies.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
5
Thereportalsoindicatesthatstateswithlongerhistoriesofmodelingandgreaterconfidenceinthevalidityofthemodelingoutputstendtomorewidelyusetheirmodelsforabroadrangeoffunctions.
TABLE1:STATUSOFSTATEWIDEMODELINGCAPABILITY‐SPRING2005
StateModel
ConditionCost
DevelopmentTime(years)
Comments
Alabama None Alaska None Arizona None Arkansas None California Operational $200,000 2.4 Colorado None Connecticut Operational $400,000 1 Delaware Operational DistrictofColumbia MPOmodel Florida Operational $1,500,000 4 Georgia Operational $65,000 1 Hawaii None IndividualislandmodelsIdaho Dormant Illinois Dormant Indiana Operational $1,500,000 3 7moreyearsforvariousupgradesIowa Developing $300,000 2 Kansas Developing HasadormantfreightcomponentKentucky Operational $370,000 2 NewmodelunderdevelopmentLouisiana Operational $500,000 CostincludessomeapplicationsMaine Operational $500,000 5 BeingrevisedMaryland None Massachusetts Revising $800,000 Michigan Operational $1,000,000 2 Minnesota Partial Mississippi Developing Missouri Operational $500,000 RevisioncompletionsoonMontana Operational FreightonlyNebraska Dormant BaseyearmodelNevada None NewHampshire Revising $2,000,000 NewJersey Operational $500,000 FreightonlyNewMexico None NewYork None County‐levelODassignmentNorthCarolina None NorthDakota None Ohio Operational $6,000,000 8 Beingrevised;$3,500,000fordataOklahoma None Oregon Operational BeingrevisedPennsylvania Developing RhodeIsland MPOmodel SouthCarolina Operational $25,000 0.5 SouthDakota None FeasibilitystudybeingconductedTennessee Developing BasedonODtableestimationTexas Operational $1,700,000 4 Utah None Vermont Operational $730,000 2.5 Virginia Operational $1,500,000 3 Washington None WestVirginia None Wisconsin Revising $850,000 2.5 Wyoming None Notes:MPOismetropolitanplanningorganization;ODisorigin‐destination.Modifiedfromsource:NCHRPSynthesis358:StatewideTravelForecastingModels(2006),Table1,p.14.[1]Datamovedfrom“Colorado”intheoriginallypublishedtableto“Connecticut”inthisversion.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
6
Accordingly,theNCHRPSynthesis358reportsthatthemostcommonmeasuresofeffectiveness(MOE)usedfrommodelsasindicatorsofsystemperformanceincludevehiclemilesoftravel(VMT),vehiclehoursoftravel(VHT),volumetocapacityratios(v/c),levelsofcongestion,and
trafficgrowthrates.Additionaloutputsmaybeusedformorespecializedmodeluses,butVMTandVHTarestandard.SomemodelsproduceMOEsforcertainperiodsoftheday,namelypeakhours,whileothersreportdailytotals.
Themaintenanceandresourceneedsfortherangeofstatewidemodelsarealsovaried.While
manystatedepartmentsoftransportationrelyonprofessionalconsultingfirmstodeveloptheirmodels,manyperformroutinemaintenancethemselves(1).Staffallocationsformodelingprogramstypicallyrangefromoneormorepersonnelwithpart‐timeresponsibilities–some
supplementedbyvaryinglevelsofconsultantsupport–uptomultiplefull‐timepersonnel.Moreover,maintenanceisperformedcontinuouslyoratfrequentintervals(onetotwoyears),andstatestypicallyperformmodelupdatesonregularcycles–somecoincidingwithreissuingof
transportationplans(typicallyeveryfiveyears),andothersusingcyclesaslongastenyears.
SurveyfeedbackreportedinStatewideTravelDemandModeling:APeerExchangeprovidesinsightintosomereasonsformodelingprogramfailures.AccordingtoRickDonnellyofParsonsBrinckerhoff,whosesurveyresponsewasquotedintheStatewideTravelDemandModeling:A
PeerExchangefortheOregonstatewidemodel,“vagueorpoorlydefinedgoalsandobjectives,”“higherthanexpectedmaintenanceandapplicationcosts,”and“lackofmanagementsupport”aresomeofthecausesformodelfailureandabandonment(p.74).Mostimportantly,acommon
andreasonabletrendinstatewidemodelingprogramsisthatstatesmustbalancemodelqualitywithtimeandbudgetconstraints(1).
Inordertoensurethatastatewidemodelingprogramiseffectiveandsustainable,bothinterms
oflaborandbudgetallocation,itsobjectivesmustbeclearlydefinedanditsutilitymustbetransparent.Asstatedin“ACriticalReviewofStatewideTravelForecastingPractice”(3),thegoalsofastatewidemodelingprogramshouldbedefinedwellinadvanceofmodel‐specific
details,suchasdataneeds,modelcomponents,computersoftware,andbudgetallocation.Theplanningneedsofthestatedepartmentoftransportationshouldsteerthemodelingprogram.
3.2 AdvancesinTravelDemandModeling
Recentresearchinthesubjectoftraveldemandforecastinghasseenashiftfromtraditionaltrip‐basedmodelingtechniquesofthefour‐stepparadigmtoactivity‐basedforecastingmodels.Thishasbeeningeneralresponsetothelimitationsofthefour‐stepprocess,theneedformodelsto
bemoresensitiveandresponsivetotheeffectsofsystemconditionsandpoliciesonmobilityandlifestylechoices,andthedesiretodisaggregatetraveldemandforecastingtothelevelofmicro‐simulationmodelingtechniques,replacingaggregatezonalcalculations(4,5,6,7,8).Since
activity‐basedmodelingconsidersthedecisionprocessesthatdictatetravelofindividualentities
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
7
or“agents,”potentiallyonacontinuoustemporalbasis,itsmethodologyadaptsitselfbettertothedynamicnatureandcomputationalcharacteristicsofmicro‐simulation.Therecould,therefore,beashiftawayfromindividual“trips”astravelunitsto“tours”withmoreadvanced
activity‐basedmodelsimplementedatregionalandstatewidelevels.
Inadditiontoservingthestandardforecastingneedsoftransportationplanning,thenewactivity‐basedmodelshavealsoshowntobevaluabletoolsforevaluatingmorespecifictransportationsystemmanagementpolicies,including:traveldemandmanagementandpeak
spreadingeffects,high‐occupancyvehicle/facilitydemand,tollandcongestionpricing,andtransitfareandparkingpricingpolicies(5,7).Theycanalsobeappliedtoplanningissuessuchastransportationequityandchangesindemographics,suchaspopulationaging,household
compositions,andlaborforcecharacteristics(5,7).
Thedatarequirementsfordevelopment,computationaldemands,validationprocesses,variabilityofresults,andcostsversusbenefitsofactivity‐basedmodeling,thoughimplementedandevaluatedonlimiteduptoregionalscales,haveyethadwidespreadapplicationona
statewidescale.Somestateswithneworrecentlyrevisedstatewidemodelshaveimplementedvaryingdegreesofactivity‐basedtraveldemandprocedures,includingOhio,Oregon,NewHampshire,Michigan,andLouisiana,withOhio’s(stillindevelopment)beingthemostadvanced.
VariousMPOsnationally,suchastheMid‐OhioRegionalPlanningCommission(MORPC),theNewYorkMetropolitanTransportationCouncil(NYMTC),andtheSanFranciscoCountyTransportationAuthority(SFCTA),alsohaveimplementedactivity‐basedproceduresintheirregionalmodels.
However,manytraveldemandpractitionersarestillskepticaloftheaccuracyandlarge‐scaleapplicabilityofthenewmodelingtechniques,aswellastheirdataandresourceneeds.Dependingonthedesiredutilityandnecessarydetailforastatewidetraveldemandmodelat
thistime,aswellasimplementationconstraints,activity‐basedmodelingmaynotyethaveafeasibleapplicationforallstatescurrentlywithtraveldemandmodels.
3.3 OngoingApplicationsofTransportationModeling
AstudypanelfortheFloridaDepartmentofTransportation,aspartofitsevaluationoftransportationmodels,providedaneffectivelistof“currentandemergingissuesin
transportationplanning”thatsummarizesabroadspectrumofpotentialapplicationsfortraveldemandmodelsandothertransportationmodels(9).Thelistincludes:
Capacitydeficienciesandcongestion Interactionbetweentransportationandlanduse
Economicdevelopmentimpactsoftransportation Freightmobilitystrategies Airquality
Systempreservation,maintenance,andoperations Safety Securityandemergencyevacuations
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
8
Equity Resourceallocationandprojectselection
TheseplanningchallengeshaveuniversalcontextsandarealsoapplicabletoVermont’stransportationsystems,developedspace,andenvironment.Therefore,itisreasonabletobe
cognizantofthesetopicswhilediscussingthecurrentandfuturefunctionalityandutilityofVermont’sstatewidemodel.
4. StatewideTravelDemandModelingattheVermontAgencyofTransportation
TheVermontAgencyofTransportationcurrentlyhasafunctionalstatewidetraveldemandforecastingmodel.In2007,themodelwastranslatedfromtheoriginalTRANPLANsysteminto
thenewCube/Voyager(Citilabs,Inc.)softwareplatformbyVHB,Inc.withupdatestotheroadwaynetwork,freightmodel,andmodelcalibrationproceduresandresults(fordocumentationaboutthisprocessrefertoVermontStatewideTravelDemandModel
Improvements:UpdatedPassengerandTruckModelsinCube/Voyager,2007).Importantly,duringthisprocessemploymentdatafortripgeneration,truckpercentagesbyregionalplanningcommission(RPC)fornonhome‐basedtrips,andthefrictionfactorfunctionsfortripdistribution
wereallupdated(10).Althoughthemodelhasbeenappliedtoanumberofproject‐leveltasks,suchastheCirc‐WillistonEnvironmentalImpactStatementandcurrentlytheWesternCorridorTransportationManagementPlan,thepotentialexistsforfurtherimprovementsandbroader
utilitytoaidVTransprojectworkandplanningintheVermont(seeAppendixA:A‐1–A‐3,A‐5).
4.1 ModelStructureandComponents
Thestatewidemodelisstructuredasatypicalfour‐steptransportationplanningmodel,
comprisedof:1)tripgeneration,2)tripdistribution,3)modechoice,and4)trafficassignment(foradescriptionofthesefourstepsinageneraltransportationplanningcontextreferto11and
12).Briefly,inthetripgenerationstep,themodeltakesinputsfromdemographicsourcesandcombinedwithtriprates,estimatesthenumberofpersontripsgeneratedperday,categorizedintosixgeneralizedpurposes:home‐basedwork,home‐basedshopping,home‐basedschool,
home‐basedother,nonhome‐based,andtruck(asapercentageofnonhome‐based).Forexample,Figure1showsthetripproductionratesforthefourhome‐basedpurposesbasedonthecross‐classificationofpersonsperhouseholdandautosperhousehold;nonhome‐basedtrip
productionsarebasedonalinearapproximationinsteadofcross‐classification,similartotripattractions.Inthetripdistributionstep,theflowsoftripsbetweeneachorigin/destinationpairofTAZareestimatedbasedonthezone‐to‐zonetraveltimes(impedance).Figure2showsthe
triplength(time)frequenciesbypurpose,whichareoneresultofthetripdistributionprocess.Themodechoicestepsplitsthetotalnumberofpersontripsintothoseusingtheroadwaynetworkandthoseusingtransit;inturn,theroadwaypersontripsareconvertedtovehicletrips
usingvehicleoccupancyfactorsbytrippurpose.Lastly,thevehicletripsareassignedtothe
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
9
roadwaynetwork,producingtrafficvolumeandVMTestimatesoneachroadway.Becausethestatewidemodelcurrentlydoesnothaveatransitnetwork,thepersontransittripsestimatedinthemodechoicesteparenotassigned.
FIGURE1:DAILYPERSONTRIPRATESPERHOUSEHOLDBYPURPOSE
0
1
2
3
4
5
6
Home‐basedWork Home‐basedOther Home‐basedSchool Home‐basedShopping
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
10
FIGURE2:TRIPLENGTHFREQUENCYDISTRIBUTION
Themodelhasa2000baseyearwithaforecastyearof2020andaten‐yearinterpolationto2030.Itcontains628internaland70externaltrafficanalysiszones(TAZ)asshowninFigure3.TheexternalTAZrepresenttravelto/fromandbetweenregionsbeyondVermont,including
neighboringstates(NewYork,NewHampshire,andMassachusetts),therestofNewEnglandandthenortheast,andCanada.Generally,theinternalTAZcoincidewithVermontmunicipalityboundaries,exceptinmoredenselypopulatedareaswheretheTAZaremoredisaggregate.The
TAZalsoaggregateto2000USCensusblockgroupboundaries.
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
8.0%
9.0%
10.0%
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60
TripLength(minutes)
Home‐basedWork Home‐basedOther Home‐basedSchool
Home‐basedShopping NonHome‐based
� � wn t d� � d� d� l e� � � � w� v� o� � � n � t � � � � � o� C� � � � w� oen et � wM� � v� oT� de t �
� � � � � � � � � � S wd� ‐ � 37R77f �
/ / �
� � � � � � Fy� � � � � � � � � � � � � � � � � � � � � � � � � �
�
�
� y � wd� � p � t � n kp dw0� � dnWWkW� dM� � r r wdoA � k 9t � /Ucmmm� 9n0Wc� n� 9s � na� nk wn� 9� � n� � ok wn� 9� � � � �� nkwd� � � dnn � kdwWc� � T� � � nkd� Mdswk n� � 9� WWM� � kdn� � � k adw WC� �
,/V� wsw� 9� nk wWk� k �
,j V� wsw� 9� r wn� r � 9� � wk w� 9� ,LV� wsw� 9� A ndw� � wk w� 9� ,GV� wsw� 9� A � 2dw� � d99 � kdw� �
,I V� wsw� 9� A ndw� � d99 � kdw�
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
12
(9)rurallocal (11)urbaninterstate (12)urbanprincipalarterial/freeway
(14)urbanotherprincipalarterial (16)urbanminorarterial (17)urbancollector
(19)urbanlocal (20)internalTAZcentroidconnector (21)externalTAZcentroidconnector
4.2 Application,ImprovementandMaintenanceoftheModel
TheVTransstatewidemodelhashadorwillhaveutilityfortransportationstudiesthroughoutthe
state,includingtheCirc‐WillistonDraftEnvironmentalImpactStatement(DEIS)(13),theMorrisvilleBypass,theBenningtonBypass(14),theWesternCorridorTransportationManagementPlan(15),andastateemployeecommuterstudy.Themodelwouldalsohave
applicabilityfortheHighwaySystemPolicyPlan(16),PublicTransportationPolicyPlan(17),RailSystem&PolicyPlan(18),theAssetManagementVisionandWorkPlan(19),theVermontLongRangeTransportationBusinessPlan(LRTBP)(20,21)–thestate’soverallplanforthemulti‐modal
transportationsystem–andtheFinalReportandRecommendationsoftheGovernor’sCommissiononClimateChange(GCCC)(22).
Theusefulnessofthemodelforproject‐levelanalyses,planningscenarioevaluations,andstorageandpresentationoftransportationsystemdatareinforcetheneedforcontinued
maintenanceandapplicationofthetool,aswellasoutreachandtrainingtoinformotherVTransdepartmentsandotherstateagenciesofthemodel’sutility.Thefollowingsectionshighlightanticipatedmodelingneedsbasedonfutureplanninggoalsandtheimprovementslikelyrequired
orrecommendedforthestatewidemodelinordertomeetthosespecificneeds,especiallythosethatarenotcurrentlywithinitscapabilities.
Dependingonthedeterminationofthelong‐rangemodelingobjectivesofVTransandthestatewidemodel’sfutureutility,itispossiblethatthestatewidemodelwouldneedadditional
refinementandupdates.Ifsuchrefinementsandupdatesweretobeimplemented,itisexpectedthattheirpurposewouldprimarilybetomeetsomeoftheplanninggoalsidentifiedintheLRTPBandGCCC,aswellasothermodelingeffortsatVTrans,includingtransitplanningandairquality
analyses.Assuch,someofthecontinuedandfuturemodelinggoalsdiscussedcoulddeterminetheneedforanumberofpotentialstatewidemodelimprovements.
4.2.1 SystemPolicyandEnvironmentalPolicyPlanning
Anumberofapplicationsofthestatewidemodelarelikelybasedonanticipatedmodelingneedsdescribedinstateandagencydocuments,suchastheLRTBPandtheindividualsystempolicy
plans.Thesedocumentsdonotexplicitlyidentifytheapplicationofthestatewidemodeltomeet
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
13
theirrecommendationsbutfromapracticalviewpoint,themodelisclearlyatooltoaidcompletionofsomeofthepolicycomponents.TheLRTBPidentifiestransportationopportunities,specificallytheintegrationoflanduseandtransportationplanningandtheevolvingfocuson
corridormanagementplanning,asmethodsforthestatetomoreeffectivelymeettransportationsystemchallenges.ThefinalreportandrecommendationsoftheGCCCcitestheneedforstrengthenedstate‐levelplanninganddecision‐makingtosupportmanagedgrowthaswellas
transportationplanningtofacilitatealternativetravelmodes,transitpriorityandtherehabilitationandmaintenanceofexistinginfrastructure.
BusandRailTransitSystemPlanning
Inadditiontotheplanninggoalsoutlinedinofficialagencydocuments,discussionswithVTranspersonnelunderscorethepotentialutilityofthestatewidemodeltosupportvariedtasksatthe
agency(seeAppendixA:A‐1–A‐3,A‐5).AtthePolicyandPlanningDivision,thereisarecognizedneedforimprovedmulti‐modalplanning,asrecommendedintheLRTBPandmorespecificallytheHighwayandPublicTransportationSystemPolicyPlans,whichwouldlikelyincludethe
creationofatransitnetworkinthestatewidemodel.Afullydevelopedtransitnetworkwouldallowplannerstoestimateridershiploadsalongexistingandproposedtransitroutessuchasintercitybustransit,toevaluateheadwaysandstops,andtoidentifypotentialroutecapacity
improvementsandextensions.Importantly,anyimprovementinthecapabilitiesanddetailofthemodel’stransitcomponentwouldrequireredevelopmentofthemodechoicemodule,sincethemodelcurrentlyapportionsafixedpercentageasatransitshare(10).Anewmodechoice
modulewouldlikelybealogitmodel,whichpredictstheselectionprobabilityofalternativemodesbycomparingthecosts(monetarycost,time,convenience,etc.)ofthosemodes(11,12).
Thedevelopmentofatransitnetworkinthemodelwouldbeanintensivebutprobablyworthwhiletaskconsideringtheimportanceoftransitmodelingrecognizedinlongrange
planningdocuments.Additionofatransitnetworkwouldrepresentasignificantimprovementtothemodel’sfunctionalityandutility.Thistransitnetworkwouldcertainlyincludebus,which
wouldusethemodel’sroadwaynetwork,andpossiblyrail,whichwouldrequirethedevelopmentofanewnetworkstructure.
RailFreightSystemPlanning
Developmentofarailnetworkaspartofthefreightmodelwouldimprovethefreightmodelcomponentaswellastheoverallmodel’sutility.Agrowingneedordesiretoshiftmorefreight
fromtrucktorailcouldstillprecipitateaneedforarailcomponentinthestatewidemodel.TheVermontStateRail&PolicyPlanidentifiesagoaltoprovidecompetitivefreightandpassengerservice,eventhoughthatreportalsorecognizestheuncertaintyofthefutureofVermont’s
intercitypassengerrailservice(18).However,withapassengerrailcomponent,ifdeemedworthwhile,thestatewidemodelcouldbeusedtoevaluateplanstoexpandandpromotepassengerrailservicebothinVermontandregionally.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
14
Thegeneralrailnetworktopology–linksandnodes–oftherailpassengertransitcomponentcouldbetransferredfromanewlydevelopedrailfreightcomponent,ifthetransitimprovementsinthemodelwereundertakenfirst.Therailnetworkstructurecouldthenbespecifically
configuredforuseinthefreightmodel.
HighwaySystemPlanning
TheHighwaySystemPolicyPlanindicatesthatforsystemmanagementandpreservation“itisdesirabletodefinedifferentsectionsofthehighwaysystembasedonfunctionalityandoveralllevelofimportanceforwhichdifferentperformancestandardsandinvestmentpoliciesare
developed”(p.ES‐5).Thisideaofsub‐networksappliestoperformancemeasures,includingpreservation,safety,mobility,andenvironment/qualityoflifeasoutlinedintheHighwaySystemPolicyPlan,andtotheprioritizationofassets.AsVermontdevelopswithgrowingpopulation
centers,thedesignationsofexistingandhithertounbuiltroadwaysaspartsofeitherthe“primary”or“off‐primary”sub‐networksmayneedtoberevised.Forecastsandanalyseswiththestatewidemodelcouldaidinappropriatelyidentifyingtheevolvinglevelofimportanceof
roadwaysinthenetworkandevaluatecertainperformancemeasures,suchasVMT,traveltimes,averagespeeds,flows,andvolume‐to‐capacityratiosforroadwaylinks.Asanextensionofthesub‐networkdefinitionprocess,thestatewidemodelcouldservetoevaluateanddeterminethe
criticallinksinthesystem,andthepossibleimpactsduetotheclosure(e.g.bridgemaintenance,naturaldisasters,emergencyevacuations,etc.)ofacriticallink.Thiswouldprovidedatafortheplanningofmanagementandresponsestrategies.
ThestatewidemodelcouldalsoservetheTrafficOperationsdepartmentresponsibleforthe
management,analysis,andreportingofVTranstrafficcountsthroughoutthestate,byaidingtrafficgrowthprojectionsandhelpingtoidentifythepotentialeffectsofnetworkdisruptionsandresultingdetours/re‐routing(seeAppendixA:A‐1).Howeverfordetailedanalysesof
roadwaysectionsorcorridorsusing,forexample,micro‐simulationmodelswiththestatewidemodel’sprojectedvolumesasinputs,itwouldfirstbeadvisabletoevaluatetheaccuracyand
applicabilityofthestatewidemodel’strafficvolumesfordirectuseinothermodelinganalysesbeforesuchapplicationswereundertaken.
EnvironmentalPlanning
Theimportanceofenvironmentalpoliciesrelatingtoclimatechangeandairqualityconditionscoulddrivetheneedforfurtherstatewidetraveldemandforecastmodeling.AlthoughVermont
iscurrentlyinattainment,airqualityconditionscouldworsenormorestringentstandardscouldresultinnon‐attainmentforcertaincriteriapollutantssuchasozoneorparticulatematter(21).Moreover,potentialfuturelimitsongreenhousegases,namelycarbondioxide,aswellasVMT
performancemeasureswouldrequireVMTforecastsandpollutantinventoryestimatesforVermont’stransportationsystem.Thestatewidemodelisavaluabletoolforsuchenvironmentalanalyses,primarilybecauseitcanfeednecessaryinputdata–VMTbyfunctionalroadwayclass
andaveragespeeds–tomobileemissionsmodels(currentlytheEPA’sMOBILEmodelandthe
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
15
newerMOVESmodel).ItisreasonabletoexpectthatairqualitymodelingandtheresultingenvironmentalpolicieswillcontinuetogainimportanceforVermontandnationally,andtheneedforincreasinglydetailedandaccuratetraveldatafromthestatewidemodelwouldgrow
concurrently.
Therearemethodstoimprovethestatewidemodel’soutputstobetterservemobileemissionsmodeling,specificallytheMOBILEmodelwhichiscurrentlyusedinVermont.AccuratedisaggregationofVMTdatabyvehicleclasscouldimproveemissionsestimates,sincedifferent
typesofon‐roadvehicles,suchaslight‐dutyversusheavyduty,havedifferentoperatingcharacteristicsandemissionsprofiles.However,atypicalfour‐steptraveldemandmodellikethestatewidemodeldoesnotinherentlyconsidervehicletypesinthismanner.Thestatewidemodel
doescurrentlydefineaportionofnonhome‐basedtripsastrucktripsbasedonapercentage(determinedbyvehicleclassificationcounts)foreachRPCinVermont,butthisdoesnottranslatetospecificvehicle‐typeVMTassignedtothehighwaysystemasamodeloutput.Therefore,it
wouldbeworthwhiletodevelopanewmeanstoaccuratelydisaggregatehighwayVMTbyvehicleclass,atleastintogeneralweightclasses(e.g.light‐dutyvehicle,light‐dutytruck,andheavy‐dutytruck)withinthestatewidemodel.Thiscouldinvolveusing24‐hourclassification
countsandconductingroad‐sidesurveys.
OtherVMTbreak‐downsthatcouldbeexploredtoimproveemissionsmodelingwouldincludeVMTbytimeofday(hourly)andVMTbyaveragespeed.Importantly,themeritofdevelopingthesedistributionsspecificallyforVermontinsteadofusingthedefaultvalues(national
averages)suppliedwiththeMOBILEmodelwouldneedtobeinvestigated.Thedefaultvaluesmaybe“goodenough,”anditwouldnotbeworththetimeandcosttodevelopVermont‐specificdistributionsthatwouldnotservetoimproveemissionsestimates,orworse,decreasetheir
accuracy.
GreenhouseGasEmissionsInventoriesandStandards
Thecurrentandfutureutilityofthestatewidemodelshouldbeconsideredinthecontextofpotentialairqualitystandardschangesandpotentialgreenhousegasstandardslegislationfor
Vermontandonafederallevel.InApril2009,theEnvironmentalProtectionAgencyreleaseditsfindingthatgreenhousegasescontributetoairpollutionthatposesathreattopublichealthandwelfare,inresponsetoa2007rulingbytheSupremeCourtoftheUnitedStatesthatrequiredthe
EPAtoreviewthepotentialimpactsofemissionsofsixgreenhousegases(24).
Concurrently,theStateofCaliforniaistakingaleadingreenhousegaslegislation,includingnewcapstandardsforlight‐dutyvehiclesandrulesforGHGreporting/inventories(25,26).Vermont,inadditiontoapproximatelyfifteenotherstates(27),haspasseditsownlegislationtoadopt
California’sGHGstandards,expectingthattheU.S.EPAwillgrantCalifornia’swaivertotheCleanAirActfortheproposedstandards.California’swaiverrequestwasfirstrejectedbytheEPAduringtheBushAdministrationinlate2007,buttheEPAhasrecentlybeendirectedbythe
ObamaAdministration,inearly2009,toreviewandreconsiderthatdecision.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
16
VermontpasseditsownruleinNovember2005,makingitsGHGemissionstandardsforlowemissionvehiclestobeidenticaltothoseofCalifornia.Intherule,titledAirPollutionControlRegulations,SubchapterXI,LowEmissionVehicles–RegulationstoControlGreenhouseGas
EmissionsfromMotorVehicles,GHGstandardsforsmallandlargelight‐dutyvehicleswouldbegraduallyphasedinbetweenmodel‐years2009and2016(28).However,VermontcannotactuntiltheCaliforniawaiverisgranted.
AsVermontadoptsCaliforniastandards,itispossiblethatthestatewillalsoseektofollow
California’sleadonGHGreportingrules.RequirementsforinventoriesofGHGemissionsforthetransportationsectorwouldlikelyemphasizeregularanddetailedreportingofVMTestimatesforGHGcontributionsfromon‐roadsources.Also,anevaluationofGHGemissionimpactswouldbe
desiredforplanningandpolicymakingpurposes(e.g.therecommendationspresentedintheVermontComprehensiveEnergyPlan,2008,(29)andVermontGovernor’sCommissiononClimateChange,2007)(22).
InMay2009,thedevelopmentanddebateofAmericanCleanEnergyandSecurityActof2009
(H.R.2454)hashighlightedtheproposedbill’smulti‐facetedapproachtoreduceconsumptionoffossilfuelsandlimitgreenhousegasemissions.RegardingthelinkbetweenthetransportationsectorandGHGemissions,asummaryofthebilldatedMay16,2009describesthe
TransportationEfficiencysectionofH.R.2454,whichwouldamendtheCleanAirActto“requirestatestoestablishgoalsforgreenhousegasreductionsfromthetransportationsectorandrequiressubmissionoftransportationplanstomeetthosegoalsbyMetropolitanPlanning
Organizationsforareaswithpopulationsexceeding200,000people”(30).
TheVermontstatewidemodelwouldbethemostsuitabletooltoforecastVMTfortheestimationprocessofgreenhousegasemissionsfromon‐roadsourcesinthetransportationsectorandtoevaluateGHG‐relatedimpactsofplanningalternativesbasedontheVMT
projections.CurrentlyinCalifornia,theCaliforniaAirResourcesBoard’s(CARB)travelactivityforecastingapproachfortransportationsectorGHGemissioninventoriesusesVMTestimates
fromtheEMFAC2007modelandregionalplanningorganizations.EMFAC2007estimatestravelactivitybasedonvehiclepopulationandvehicle‐age‐specifictravelaccumulations,whicharematchedtoVMTestimatesfromtheregionalplanningorganizations’transportationmodels(31).
SimilartoCalifornia,VermontshouldmaintainitplanningtoolsandproceduresforVMTforecasting,includingthestatewidemodel.
4.2.2 OtherModelRefinements
Additionalrefinementtaskscouldbeundertakentoimprovethemodel’sfunctionality.Theaccuracyofthemodel’sbaseyearandprojectedvolumesshouldbefurtherassessed.For
regionalairqualitypurposesandplanningprocesses,theneedforreliableestimatesofvehiclemilesoftravel(VMT)wouldbeparamount,andotherusesofthestatewidemodel,suchasanalysisofasectionofitsvolumeoutputsusingmoredetailedmodelingtoolssuchastraffic
simulation,wouldgreatlydependontheaccuracyofitsestimates.Tothisend,thetaskof
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
17
assessingandimprovingthereliabilityofthemodel’svolumeprojectionscouldincludefurtherrefinementofthefourplanningsteps,inputdatamodifications,andadditionaliterationsofcalibrationandvalidation.
Four‐StepModelAlgorithms
Furtherrefinementofthemodel’soutputscouldbeaccomplishedbyincorporatingoneormore
feedbackloopswithinthemodel’salgorithmicprocess.Sincetripdistributionestimationsarebasedoninterzonaltraveltimesasarethetravelmodeutilityvalues(traveltimecost,perceivedcost,etc.)inthemodechoicestep,itiscommontofeedthelinktraveltimesestimatedinthe
trafficassignmentstepbackintothetripdistributionandmodechoicesteps.Thisisespeciallyimportantiftrafficassignmentindicatescongestionthatresultsinlinktraveltimessignificantlydifferentfromthoseinitiallyassumed.Theresultingfeedbackwouldproduceaniterativeprocess
thatwouldcontinueuntilanequilibriumconditionhadbeenmet.
InputDataUpdatesandFurtherCalibration&Validation
DuringtheVHB,Inc.updateandmigrationofthestatewidemodeltoCube/Voyagerin2006‐2007,thetraveltimefrictionfactorsfortripdistribution,originallybasedonthe1994Vermonthouseholdsurvey,wereupdatedusingthefunctionsdescribedintheNCHRPReport365(12).
VHB,Inc.alsorevisedthetripattractionregressionequations,butthetripproductionrates,originallybasedonthe1994householdsurvey,werenotchanged.Newdemographic,socio‐economic,andtraveldatafromupcomingupdatesinthe2008‐2009NationalHouseholdTravel
Survey(http://nhts.ornl.gov/nhts2008.shtml)andthe2010USCensuswouldprovideabasistoevaluateandpossiblyrevisecurrenttriprates.Furthermore,withthenewdata,itwouldalsobepossibletoevaluatethefeasibilityandmeritofapplyingregional‐specifictripratesandfriction
factorswithinthemodel,forexamplebycountyorRPC.ItisimportanttonotethatfollowingVHB,Inc.’srecentworkonthemodel,someadditionalcalibrationwasdoneatVTransforTAZin
westernportionsofVermontfortheWesternCorridorTransportationManagementPlanandsubsequenttothat,CambridgeSystematics,Inc.performedfurthercalibrationwhilerunningthemodelforthatstudy.
RoadwayGradeData
Thenetworklinksinthemodelwithfunctionalroadwayclassifications(i.e.allofthelinksexcept
thecentroidconnectors)currentlyhaveadefaultvalueof“1”forthe“TERRAIN”datafield.AccordingtotheVHB,Inc.2007report,adefaultvalueof1,whichindicateslevelterrain,wasassignedtothelinksduetolackofbetter,morespecificterraininformation.Updatingthe
model’snetworklinkswithaccurateterraininformation,orpotentiallymorespecificdatasuchasgrade,couldserveasaninventoryforVermont’sroadsandimprovethemodel’sutilityinfutureon‐roadmobileemissionsandairqualityestimatesusingtheUSEnvironmentalProtection
Agency’sMOVESemissionsmodel,whichconsidersroadwaygrade(aspartofavehicle’soperatingmodeforrunningemissions)initsestimates.ThestatewidemodelcouldprovideVMT
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
18
totalsbygrade.However,ifdefiningindividuallinkgradesisdeemedimpractical,categoricalinformation,suchasgeneralterraintype,couldbedefinedforthemodel’snetworklinksandusedtoapproximatemoredetailedgradevaluesasneeded.Terraincategoriescouldinclude
level,rolling,andmountainous,similartothe2000HighwayCapacityManual.
IntegrationwiththeChittendenCountyMPOModel
PossibleintegrationofthestatewidemodelwiththeCCMPO’sregionalmodelofChittendenCountycouldfurtherpromoteanalysesusingthemodelsjointly,tocomplementeachother.TheCCMPOmodeliscontinuallymaintainedandhasrecentlyundergoneanewseriesofupdates
(23).ForcertainprojectsandplanninganalyseswithinChittendenCounty,thestatewidemodelcouldbereliedupontoevaluatetransportationeffectsbeyondtheregionalboundaryoftheCCMPOmodel(seeAppendixA:A‐4).OnesuchexampleistheCirc‐WillistonDEIS.Transferability
ofnetworkandTAZdatafromtheregionalmodeltothestatewidemodel,orviceversawouldhavedesiredutility.Also,byincludingsomeofthesametravelmodesinthestatewidemodelasintheCCMPO–namelyauto,carpool,bus,andpossiblyrail–therecouldbeimproved
transferabilityoftripdatabetweenthetwomodels.Thiswouldalsorelyonrectifyingthetemporalresolutionofthetwomodels,daily(thestatewidemodel)versuspeakhour(theCCMPOmodel).Also,themodelsarecurrentlyindifferentsoftwareplatforms;thestatewide
modelisinCube/VoyagerandtheCCMPOmodelisinTransCAD.Ifthatweretoremainthecasefortheforeseeablefuture,ameansofdatatransfer(import/export)wouldbeneeded,suchaswiththeuseofdatabasefilesorspreadsheets.
4.2.3 Maintenance
Regularmaintenanceofthemodelshouldbedonecontinuously,includingminorcalibrationand
validationprocessesorasneededbyspecificprojectsemployingthemodel.Moresignificantupdatesandrevisionstothemodelincludingupdatestoinputdatasuchasdemographicand
employmentfiguresandroadway,transit,andfreightnetworkcharacteristics,andpossiblythemodel’salgorithmsandlogiccouldbeonascheduledcycleofapproximatelyfivetotenyears.Updateprogramscouldcoincidewiththereleaseofrevisedsystempolicyplansorthe
publicationofupdateddatasources,suchastheNationalHouseholdTravelSurveyandthe2010USCensus.DependingonairqualityattainmentstatusinVermont,airqualityconformityneedscouldpotentiallyrequireaccelerationofthemodel’supdateschedule.
AccordingtotheLRTBP,theIntermodalSurfaceTransportationEfficiencyAct(ISTEA,1991)
stipulatedthatthestatewidetransportationplanmustcoverforecastsforaminimum20‐yearhorizon.ThatstipulationhasprogressedinTEA‐21(1998)andsubsequentlyinSAFETEA‐LU(2005).Currently,thestatewidemodelforecaststo2020and2030,thoughthe2030forecastis
basedonextendingthegrowthfrom2000to2020byanadditionaltenyears(10).Withtheyear2010approaching,moreaccurateforecastsfor2030wouldberequiredandshouldbedevelopedtomaintaincompliancewiththeminimum20‐yearhorizonruleintheLRTBP.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
19
5. OptionsfortheStatewideModelandModelingProgram
VTranshasanumberofoptionsforthefutureofitsstatewidemodel.VTransmustconsiderthefeasibilityofcontinuingitsmodel,givenanexpectedfuturelevelofutilityofthemodel
comparedtothetimeandbudgetresourcestokeepitactiveandcapableofmeetingtheAgency’sneeds.Beyondthatevaluation,therearelong‐termdecisionsconcerningthestateofthemodelandhowitscurrentfunctionalitydoesordoesnotmeetthedesiredplanning
applicationsofthemodel.
Thecurrentandenvisionedlevelandextentofmodelusewouldlargelydictatethespecificsofifandhowthemodeliskeptactive.Ifthemodelatitscurrentleveloffunctionality,givenperiodicupdatestoinputdata,wouldsufficientlyandcost‐effectivelymeettheplanningneedsofVTrans,
thenitwouldbebeneficialforVTranstokeepthemodelactivewithaclearprogramforitsupdateandapplication.Goingfurther,ifthereisadesirewithintheAgencyforincreasedandmorewidespreaduseofthemodel,perhapsfortrafficresearchapplications,roadwayasset
management,performancemeasuredeterminations,andperhapscoordinationofplanningworkwithotherplanningorganizationsinVermontsuchastheCCMPOandRPCs,thentherewouldbecausetodevelopaprogramtorefineandimprovethemodeltomeetthosegoals.
5.1 FourOptions
Thefollowingfouroptionsgivegeneraloverviewsoftheworkitems,relativetimeandbudget
needs,andprosandconsdependingontheAgency’sdecisionforthestatewidemodel.Table2providesasummaryoftheoptions.
5.1.1 OptionI–Discontinuethemodel
ThisoptionwouldhaveVTransshelvethemodelandrelyonconsultant(s)forfulfillingitsforecastingneedsonanas‐neededbasis.Itispossiblethattheconsultant(s)woulddesireaccess
tothemodel–atwhateverconditioninwhichitwouldbeatthetime–fortheprojectmodelingneeds.Inthiscase,VTranswouldhavethemodelinactivebutavailableforitsconsultant(s).Ifneeded,theconsultant(s)wouldthenberesponsibleforanynecessaryupdatestothemodelin
ordertouseitforthespecificanalysis.
TABLE2:OPTIONSSUMMARY
Option WorkItems ResourceRankingI Discontinuationofthemodel
Noprogramforperiodicupdatesofthemodel VTransrelianceonconsultant(s)forforecastmodelingneeds
4th(leasttimeandbudget[1]requirements)
II Programforperiodicupdatesofthemodel VTranssupervisionofmodelupdatesandapplication DevelopmentofprogramforcontinuedmodelusebyVTrans&
DEC/ANR(e.g.traveldemandforecastingforplanningandair
3rd
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
20
qualityanalyses)III Programforperiodicupdatesofthemodel
Formulationofdetailedmodelworkplan,includingthetype/extentofimprovementstobemadetothemodelandtimeframe
Implementationofimprovements/refinementstomodelcomponentsandprocedures
VTranssupervisionofmodelupdates,improvementprogram,andapplication
OutreachwithinVTranstoraiseawarenessofmodelfunctionalityandpromotemodeluse
2nd
IV Programforperiodicupdatesofthemodel Formulationofdetailedmodelworkplan,includingthe
type/extentofimprovementstobemadetothemodelandtimeframe
Implementationofimprovements/refinementstomodelcomponentsandprocedures
VTranssupervisionofmodelupdates,improvementprogram,andapplication
OutreachwithinVTranstoraiseawarenessofmodelfunctionalityandpromotemodeluse
CoordinationofmodelingproceduresandplanninggoalswithotherplanningorganizationsinVermont(CCMPOandRPCs)
1st(mosttimeandbudgetrequirements)
Notes:[1]ThisdeterminationgreatlydependsontheamountofworkcontractedbyVTranstoconsultant(s);ifsignificant,thisoptionmayexceedOptionIIinbudgetresourcerequirements.
Asapossibleextensionofthisoption,theconsultant(s)couldprovidethemodelupdatesandan
updatesummarytoVTransattheendoftheproject,suchthatthemodelwouldexperienceselectedupdatesonaproject‐basisinsteadofonadefinedschedule.However,animportantcaveattothisprocesswouldbethatmodelupdateswouldbeonan“adhoc”basis,potentially
performedbymorethanoneconsultant,sotherecouldbeanissuewiththeconsistencyandscopeofthemodelupdates.Therefore,VTranswouldneedtoreviewandverifytheupdates–a
processthatmaynotbeattractiveconsideringthegeneralgoalofthisoption,whichisforVTranstosignificantlyreduceitsnecessarytimeandresourcesforthemodel.
Worktypeandhours
Workandhourswoulddependonaper‐projectbasis,withVTranscontractingandsupervisingaconsultant,orconsultants.
Pros
Forthemostpart,alow‐costoptionsinceVTranswouldnothavetoallocatetimeand
budgetresourcesformaintenanceandupdatingofthemodelingprogram. Onanas‐neededbasis,VTranswouldonlypayforwhatitneedsperproject(i.e.VTrans
wouldnotfundadormantmodel).
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
21
Pointofuncertainty:Aprodependingonifthecosttokeepmodelactiveandrunitwouldbegreaterthanthecosttocontractandsuperviseanoutsideconsultantforforecastingwork.
Pointofuncertainty:Amountofprojectworkcontractedtoconsultant(s);alowamountofprojectworkwouldkeepcostsforVTransdown.
Cons
VTranswouldhavetorelyonconsultantsforprojectforecastingneeds. Aresurrectionofthemodelinthefutureforsomemandatoryanalysisneedwould
requiresignificationresources,ofbothtimeandbudget. Pointofuncertainty:Acondependingonifthecosttokeepmodelactiveandrunit
wouldbelessthanthecosttocontractanoutsideconsultantforforecastingwork.Ifthis
werethecase,OptionII,below,maybeamorecost‐effectivechoicesinceahighamountofprojectperformedbyconsultant(s)workcouldbeoverlycostlyforVTrans.
5.1.2 OptionII–Maintainthemodelatitscurrentlevelofcapability,withperiodicupdates
Thisoptionwouldincludeperiodicupdatestothemodel’sinputdata,suchasnewUSCensus,NationalHouseholdTravelSurvey(NHTS),andemploymentdata,yearlyAADTcountsandnewly
builtroadwaysforthehighwaynetwork.Themodelupdateswouldnotincludechangestotheunderlyingmodelproceduresandassumptions.ItisassumedthatVTranswouldstillutilizethemodelforrelevantprojectanalyses,whiletheUVMTRCand/orconsultant(s)wouldbe
contractedtoperformtheperiodicupdatesandnecessarymodelruns.
Thefeasibilityofthisoptionwoulddependontheextenttowhichuseofthemodelinitscurrentformwouldactasreimbursementforthetimeandfundsputintoit.AnupdatedbutdormantmodelwouldbeofnovaluetoVTrans.
Exampleperiodicupdatesofinputdata
ForUSCensusandNHTSdata,updatescouldoccureveryfivetotenyears,dependingondataavailability.USCensusiseverytenyears,butotherdemographicandhousehold
datasources,suchasNHTS,maybeavailableonamorefrequentbasis. Employmentdatacanbeupdatedeveryonetofiveyears,dependingonavailabilityof
newdata.
Newhighwaydata,suchasnewroadwaysand/orcapacityimprovements,canbeupdatedonafive‐yearinterval,orasneededdependingonprojectanalysisneeds.AADTcountdatacouldbeupdatedyearly.
Significantlandusedevelopmentscanbeupdatedonafive‐yearinterval,orasneededdependingonprojectanalysisneeds.
Moredetailed,lessfrequentupdatescouldincludenewhouseholddailypersontrip
rates,whicharecurrentlybasedona1994Vermonthouseholdsurvey.Anewsurveywouldlikelybeneededtodeterminenewthetriprates.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
22
Note:Ingeneral,periodicupdateswouldbeneededatleasteverytenyearstomakethemodel’sbase‐yearcurrentandensureforecastingtoa20‐yearhorizon.Forexample,themodel’sbaseyeariscurrently2000withaforecastto2020.Duringanupdateprocessfor
baseyear2010,theforecastyearwouldhavetobeupdatedto2030. Note:Updatesofinputdataandmodelbaseyearwouldrequirere‐validationofthe
modeland,ifneeded,newcalibrationofmodelparameters.
Worktypeandhours
Workwouldinclude1)modelupdatesand2)modelapplication.Itispossiblethattheentityresponsibleformodelupdateswouldnotperformmodelapplication.Forexample,theUVMTRCcouldperformmodelupdatesregularlywhileaconsultantcouldrunthe
modelonaper‐projectbasis.Oroneentitycouldberesponsibleforalltasks. Workhoursformodelupdatescouldbedeterminedbasedonanupdateschedule.Hours
formodelapplicationwouldbemorevariableandwouldbedeterminedonanas‐needed
basis.Forthepurposesofthispreliminaryevaluation,itisassumedthattheworkhoursrequiredformodeldataupdatesofthisnatureandcorrespondingtasks(checking,re‐validation,andcalibration,ifneeded)wouldbeapproximatelyone‐tenthoftheduration
oftheupdateperiod.Forexample,toupdatedataonaten‐yearinterval,itwouldtakeapproximately12monthsofworktime,everytenyears.Updatesonaone‐yearintervalwouldtakeapproximately1–1½months,everyyear.
Pros
Likelytheleastexpensiveoptiontokeepthemodelactive,up‐to‐date,andavailableforusebyVTrans.
ScheduledupdatescouldbeperformedbytheUVMTRCand/oraconsultant,with
managementbyVTrans.
Cons Themodelwouldnotgainfurtherfunctionalitybeyondthecurrentlevel.
Themodelwouldnotberelevantfordetailedtransit/multi‐modalplanningefforts.
5.1.3 OptionIII–Improvethemodel’scapabilityforVTrans(includingDEC/ANR)analyticalobjectives
ThisoptionwouldincludenecessaryupdatestothemodelasoutlinedintheOptionII,andwouldalsoincludefurtherimprovementsandrefinementstothemodelandtheVTransmodeling
process.UnderOptionII,themodelcouldbeusedinitscurrentstatetoprovideVMTestimatestoDEC/ANRforgreenhousegasandotheron‐roadpollutantemissionanalyses.However,OptionIIIprovidesforfurtherrefinementofmodeloutputswhenprovidingVMTdataforairquality
analyses.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
23
Thefeasibilityofthisoptionwoulddependontheextenttowhichuseoftheimprovedmodelwouldbeaformofreimbursementforthetimeandfundsputintoit.AnimprovedandupdatedbutdormantmodelwouldbeofnovaluetoVTrans.
Exampleimprovementsandrefinements
Transitnetwork,possiblywitharailcomponent. Modesplitmodule. Feedbackbetweenmodelingsteps,namelytrafficassignmentandtripdistribution.
Newhouseholddailypersontripratesorverificationofcurrentrateswithupdatedsurveydata.
Aprogramofmorefrequentupdatessothatthemodelcanaidinbase‐year
determinationofperformancemeasures,AADTestimatesbytrafficresearch,androadwayassetmanagementandsafetydataneeds.
ProcedurefordeterminingVMTbyvehicleclassconsistentwithon‐roademissionsmodel
(e.g.EPAMOBILE’s16vehicleclasses);procedurewouldnotnecessarilyoccurwithinthemodelandinsteadcouldbeapost‐procedurewherethetotalVMTforecastedbythemodelcouldbedisaggregatedbyvehiclefractions(vehiclefractionscouldbedefinedfor
theentirestate,orbyregion,orbyroadwayfunctionalclass,orbysomecombinationofareaandroadwayclass).
Defineroadwaygradeorterraindatatothemodel’shighwaynetworklinks
Developanintra‐agencyoutreachprogramforuseofthemodelinVTrans,sothatotherdivisionsareawareofthemodelanditscurrentuses,andtosolicitdetailedplansforhowmodelcangainbroaderutility.
Worktypeandhours
Formorecompleximprovementstothemodel,suchasatransitnetworkoramodesplitmodule,VTranswouldneedtocontractaconsultanttoperformtheworktasks.Duration
ofworkwouldgreatlydependonthenatureofthemodelimprovement/refinementtasks.Morebasicupdates,asoutlinedinOptionII,couldbeperformedindependentlyandasdescribedinOptionII.
AsmallcommitteeofstakeholderswouldbeneededcomprisedofVTransandotherrelevantstateagencystaffmembers,UVMTRCrepresentatives,andinvolvedprivateconsultants,ifany,todevelopascopeandworkplanforthemodel’supdates,
improvements,andapplication.
Pros Expandsfunctionalityofthemodel,makingitsuitableforabroaderrangeof
applications.
Couldgenerateincreased“awareness”andutilityofthemodel. Couldimproveaccuracyofmodelforecasts.
Cons CostlierthanOptionsIandII.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
24
Improvedfunctionalitywouldnotnecessarilyleadtoincreaseduseofthemodel–increaseduseofthemodelmaybemorerelianton“awareness”ofthemodelbyotherVTransdepartmentsandstateagencies,andmayneedtoprecedemajormodel
improvementstomakethoseimprovementsworthwhileandcost‐effective.
5.1.4 OptionIV–Improvethemodel’scapabilityforVTransandcoordinationwithanalytical/planningobjectivesofotherorganizationssuchasCCMPOandRegionalPlanningCommissions
ThisoptionwouldincludenecessaryupdatestothemodelasoutlinedinOptionII,andwould
likelyincludesomeoralloftheimprovementslistedinOptionIII.Underthisoption,morespecificrefinementswouldlikelyoccurinresponsetomodelingneedsoftheCCMPObeyondChittendenCountyandtheindividualRegionalPlanningCommissions.
Forexample,theupcoming2060MetropolitanTransportationPlan,whichtheCCMPOwill
prepare,isexpectedtoforecastgrowthandtrip‐makingtrendsfortheMPOregionforthenextfiftyyearsandevaluatedevelopmentandtransportationsystemplans.DuetotheanticipatedincreaseoftripsbetweenChittendenCountyanditsneighbors,suchasFranklin,Lamoille,and
AddisonCounties,thereisadesireformoredetailedtraveldemandforecastingforthoseneighboringareas,whicharebeyondtheboundaryoftheMPO’sregionalmodel.Currently,thestatewidemodel,whichspatiallycoverstheareasneededforthepreparationoftheMTP,does
nothavetherequiredforecastingcapabilitytoyear‐2060.Inresponse,improvementstothestatewidemodelcouldincludemoredistancehorizonyearforecasts,suchas2060,andmechanismsfordataconsistencyandtransferwiththeCCMPOregionalmodel.
Worktypeandhours
SimilartoOptionIII,butwithmorerequiredtimeandbudgetresourcesforfurtherimprovementsandcoordinationwiththeCCMPOandtheRPCs.
AsmallcommitteeofstakeholderswouldbeneededcomprisedofVTransandotherrelevantstateagencystaffmembers,CCMPO,RPCandUVMTRCrepresentatives,andinvolvedprivateconsultants,ifany,todevelopascopeandworkplanforthemodel’s
updates,improvements,andapplication.
Pros CreatesadefinedroleforthestatewidemodelintheCCMPOandRPC’splanning
processes.
HelpstoformamoreunifiedplanningprocessforVTrans,theCCMPO,andtheRPCs.
Cons Costliestofthefouroptions,sinceitrequiresthegreatestextentofmodelupdatesand
improvementsaswellasincreasedcoordinationwithorganizationsoutsideofVTrans.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
25
5.2 OptionsandModelStrengthsandWeaknesses
Table3highlightsgeneralstrengthsandweaknessofthecurrentstatewidemodel,andalsoliststheoptionoroptionsthatcouldpotentiallyaddresseachweakness.Anumberoftheweaknesseslistedcouldbeconsideredsuchonlyinthecontextofadesired,moreextensiveutilityofthe
model.Thatis,themodeliscurrentlycapableofperformingitspresentlyintendedfunctions,regardlessoftheweaknessesordeficiencieslistedhere.
TABLE3:MODELSTRENGTHS&WEAKNESSWITHRELEVANTOPTIONS
Strengths Weaknesses CategoryofWeakness
Option(s)toAddressWeaknesses
Generallyup‐to‐datetraveldemandmodelincurrentsoftwareplatform(Cube)
Base‐year2010willsoonbeneeded,witha2030forecastyear
InputDataandRates
OptionII/III/IV
FourStepmodel(widely‐usedandacceptedmodelingmethodology)
Potentiallyout‐datedcalibrationoftriprates,basedon1994Vermonthouseholdsurvey
InputDataandRates
OptionIII/IV(possiblyOptionII)
Well‐developedandwell‐organizedTAZandroadwaynetworklayers
Noroadwaygradedatainnetworklayer
InputDataandRates
OptionIII/IV
Clearandwell‐documentedmodelstructure/procedure
Nofeedbackbetweenmodelsteps
ModelAlgorithm
OptionIII/IV
Broadrangeoftrippurposes(HBW,HBSC,HBSH,HBO,NHB)
Notransitnetwork/assignment ModelComponent
OptionIII/IV
Recentmodelapplicationand"awareness"ofmodelatpublicandprivateentitiesthroughoutthestate(e.g.CCMPO,CAMSYS,VHB)
Nomodesplitmodule(instead,fixedpercentagesharesbasedoncomparisonofhighwaytimesandtransittimes)
ModelComponent
OptionIII/IV
‐‐ Nofreightrailnetwork/assignment
ModelComponent
OptionIII/IV
‐‐ Limitedintra‐agency"awareness"ofmodelfunctionanduses
ModelingProgram
OptionIII/IV
6. TravelDemandModelingSoftwarePackages
Theincreasingprocessingpowerandutilityofpersonalcomputershaveprovidedanopportunityfordevelopmentandmarketingofever‐improvingtraveldemandmodelingsoftwarepackages.Coupledwiththefeaturesofgeographicinformationsystems(GIS),thesemodelsprovidea
valuabletoolforplannersanddecisionmakers.Somecommonlyusedsoftwarepackagestoday,bothnationallyandglobally,includeCubeanditspassengerdemandmodelingmodule,Voyager(anewincarnationofTRANPLAN/TP+softwarelineage),EMME/2,TransCAD,andVISUM.
Threemodelingpackageswerechosenforapreliminaryreview.Cubewasselectedsinceitisthe
nativeplatformofthecurrentVTransmodelandisawell‐establishedmodelingsoftware
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
26
package.TransCADrepresentsamajorshareofnationalandglobalmodelingtodayandisusedinVermontfortheChittendenCountyMPOregionalmodel.VISUM,thoughusedtoalesserextentthanCubeandTransCAD,isarobustmodelthatispartofanintegratedsoftwaresuite,including
VISSIM,apremiermicro‐simulationmodel.Table4summarizesthefeaturesandgeneralinformationaboutthethreesoftwarepackages,andthefollowingsectionsdiscussthepackagesingreaterdetail.
Anewerandhithertounvettedpackageforpotentialstatewidemodelingapplicationis
TRANSIMS(TRansportationANalysisandSIMulationSystem),anactivity‐basedtraveldemandmodelrepresentingindividualtravelersinitiallydevelopedattheLosAlamosNationalLaboratory.Itemploysthedisaggregatemodelingtechniquesoftheactivity‐basedparadigmwith
integrateddynamicmicroscopicnetworksimulationmodeling.TRANSIMSisanewandongoingprogrammingeffort,undergoingiterationsandversionupdatesasanopen‐sourceapplication(http://transims‐opensource.org).Itisexcludedfromthisevaluationduetolimitedapplication
thusfar,especiallyonastatewidescale.
6.1 Cube/Voyager
TheVTransstatewidepassengerdemandmodeliscurrentlyintheCube/Voyagerplatform.CubeisdevelopedbyCitilabs,Inc.andisasuiteofspecificmodulestoaccomplishabroadrangeofmodelingandplanningapplicationsrunningintheMicrosoftWindowsoperatingsystem(32).
CubeBaseisthefoundationofthesoftwareandhousestheintegratedArcGIS(developedbyESRI)interfaceandthemenuswiththesoftware’sfunctions.MappingfeaturesandnetworkeditingareaccomplishedusingtheGISinCubeBase.CubeBasealsomakesusesofgeodatabases
throughtheDatabaseManager,allowingquickaccesstomapdataformanipulation,display,anduseinVoyagermodelsteps.IntegratedwithCubeBaseenvironment,theprimarymodelingmodulesinclude:
Voyager–passengerdemandmodeling
Cargo–freightdemandmodeling Land–Landuseforecasting AvenueandDynasim–trafficanalysisandmicro‐simulation
Analyst–travelmatrix/triptableestimation
CubeallowstransportationplanninguserstodeveloptheirplanningmodelsusingtheScenarioandApplicationManagers.ScenarioPlannersorganizesmodelrunsbycategory,suchasforecastyearorplanningalternative(e.g.,theVTransmodelhasthreescenariosinCube:baseyear,year
2020,andyear2030).TheApplicationManagerusesahierarchicalflowchartstructureandscriptingtodefinethevariousstepsintheplanningmodelandprovidesaclearviewofeachpartoftheprocess.TheopenstructureofApplicationManagerallowsfortheapplicationofthe
traditionalfour‐stepprocess,includingthevariousmethodologiesavailabletoaccomplisheachstep,andotherapproaches,suchasactivity‐basedanddiscretechoicemethods.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
27
Multi‐modalpassengerdemandmodelingispossibleinCube/Voyager,includingroadway/highway,transit,pedestrians,andbicycles.CubeCargoincludesthefreightforecastingprocedures.Cube/Avenueprovidestoolsforviewingandanalyzinglinkflows,turningmovement
volumesatintersections,andtrafficoperationsimpacts.Cube/Dynasimisatrafficmicro‐simulationmodelforvideopresentationoftrafficconditions.
6.2 TransCAD
DevelopedbytheCaliperCorporation,TransCADisarobustGISfortransportationplanningapplicationsandoperatesintheMicrosoftWindowsoperatingsystem(33).TransCADcan
performthefour‐stepforecastingprocess,eithermanuallyusingbuilt‐inmenusorthroughtheuseofcustomcodingintheGISDeveloper’sKit(GISDK)interface.TransCADprovidesalternatemethodologiesforeachstepofthetransportationforecastingprocess.Tripgenerationcanbe
accomplishedusingcross‐classificationtechniqueswithuser‐definedtripratesorapplicationofestablishedtripratesfromtheITETripGenerationManualandNCHRPReport365.Gravitymodels,growthfactors,orinterveningopportunitiescanbeappliedfortripdistribution.Likethe
othersteps,modechoicemethodscanbeuser‐definedorperformedusinglogitmodelapplicationfeatures.Trafficassignmenthasanumberofpossiblemethodologies(equilibrium,all‐or‐nothing,incremental,systemoptimal,etc.)andTransCADalsofeaturesanumberoftools
toanalyzeanddisplayassignmentresults.
TheGISisusedfordevelopment,manipulation,anddisplayofmodelcomponents,includingtrafficanalysiszones,networks,routes,andunderlyingdatastructures–tables,matrices,andmaps.Numerouspassengertransportsystemscanbemodeled,includingroadways,transit,
freight,andnon‐motorizedmodes–pedestriansandbicycles.Asapowerfuldatatool,TransCADalsoincludesaplethoraofthemostcurrentUSCensusdataforvaryingspatiallevelsandprovidestoolsforaccessingandviewingtheUSCensusdata.Moreover,routingfunctionality
allowsforlogisticsanalysesandsystemplanning.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
28
TABLE4:SUMMARYOFCUBE,TRANSCAD,ANDVISUMFEATURESANDFUNCTIONALITY
FEATURES/SPECIFICATIONS
Cube TransCAD VISUM
Developer Citilabs Caliper PTV
CurrentVersion 5 5.0 10
VendorSupportandSoftwareServices
Technicalsupport,training,existingmodelconversion,andcustom
moduledevelopment
Technicalsupport,training,andcustomsoftware
developmentbasedonuserneeds
Technicalsupport,training,andcustomsoftware
developmentbasedonuserneeds
VendorStaffOffices
SanFrancisco,CA/WashingtonDC/Philadelphia,PA
Boston,MA/WashingtonDC(PTVAmericaoffices)
Portland,OR/Wilmington,DE/Austin,TX
Micro‐simulationCompanion
Dynasim5 TransModeler2.0VISSIM5(oftenusedasa"stand‐alone"model)and
HCMcompatibility
PCPlatform Windows Windows Windows
SoftwareStructure
"Base"usingArcGISwithmodularextensions,buttightlyintegrated,Extensions:Voyager(passenger),Cargo(freight),Avenue(trafficanalysis),Analyst(triptableestimation),Land(landuse
forecasting),Dynasim
AGISwithallfeaturesareinasingle,integratedplatform;TransModelerseparate
Allfeaturesareinasingle,integratedplatformusingArcGIS,VISSIMintegrated
GISComponent EmbeddedGISfromESRI IntegratednativeGIS EmbeddedGISfromESRI
NetworkEditorGIS‐based(integratedformof
ArcGIS)GIS‐based(integrated,native)
GIS‐based(integratedformofArcGIS)
EaseofUse
Flowchart‐basedApplicationManagerfordevelopingmodelingprocess("wrapper"),ScenarioManager,scripting,toolbars
Menus,scripting,toolbars(no"undo"featureformanytasks),Model/Scenario
Manager
Menus,scripting,toolbars
DataManagementTools
Matrixmanipulation,tablesMatrixmanipulation,tables,USCensusdata/geographic
datatoolsincludedMatrixmanipulation,tables
ModelingTechniques
four‐stepModel,Activity‐basedDemandModel,numerousdiscretechoiceandassignmentoptions
four‐stepModel,Activity‐basedDemandModel,
numerousdiscretechoiceandassignmentoptions
four‐stepModel,Activity‐basedDemandModel,
numerousdiscretechoiceandassignmentoptions
ModelFeedback
Methodsoffeedbackfortripdistribution/modechoice/traffic
assignment,economicandlandusefeedback,canconsidertrafficsignaldata/capacityinassignmentprocess
Methodsoffeedbackfortripdistribution/mode
choice/trafficassignment,canconsidertrafficsignal
data/capacityinassignmentprocess
Feedbackforintegrateddistribution/assignment
loops
ModalModelingPassenger,Freight,Transit,
Pedestrian,BicyclePassenger,Freight,Transit,
Pedestrian,BicyclePassenger,Freight,Transit,
Pedestrian,Bicycle
FEATU
RES/SP
ECIFICATIONS
CommonPracticeforModelImplementation
Codingofcustomapplications/interface,
User/developertrainingandcertification
Codingofcustomapplications/interface,
User/developertrainingandcertification
Codingofcustomapplications/interface
CurrentUsersVermontDOT,MaineDOT,CaliforniaDOT,FloridaDOT,WisconsinDOT,
ARC(GA),etc.
CCMPO(VT),MichiganDOT,OhioDOT,IndianaDOT,North
CarolinaDOT,SCAG(CA),NYMTC(NY),etc.
WashingtonDOT,NewYorkStateDOT,CapitalDistrictTransportationCommittee
MPO(NY),etc.Summaryinformationcompiledfromsources:9,32,33,34,35,36,37.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
29
6.3 VISUM
DevelopedbyPTV,VISUMisusedbothnationallyandgloballyfortraveldemandmodelingandtransportationplanning,thoughtoalesserextentthaneitherCubeorTransCAD.VISUMisofferedinanumberofpackagelevels,dependingonuserneeds,andincludesaversionofthe
micro‐simulationmodel,VISSIM,aspartofthePTVVisionSuite(34).Itiscapableofimplementingabroadrangeofplanningmodelmethodologiesandincorporatesallstandardmodesoftransportation–drive‐aloneauto,carpool,publictransit,bicycles,pedestrians,and
trucks.VISUMusesanintegratedGISfromESRI(similartoCube),fordisplayandnetworkediting.Furthermore,ithastheadvantageofintegrationwithVISSIM,awidelyusedandrespectedmicro‐simulationmodel.
Moreadvancedfunctionalityincludesactivity‐basedmodeling,dynamicassignmentprocedures
withlinkandintersectionmodels,anddetailedtransitassignmentwithoperationalanalyses.Activity‐basedmodelingispossibleusingVISEM,asystemthatperformstraveldemandestimatesastripmatricesforinputintoVISUM,thusreplacingthetraditionalstepsoftrip
generation,tripdistribution,andmodechoice.VISUMoffersanumberof“postassignment”analysisfeaturesincludingtraveltimeisochrones,nodeflows,subareanetworkisolation,trafficsignaleditor,andintersectionmodeling.VISUMalsoreadilyimportsmodelsfromothersoftware
packages,includingCube,TransCAD,EMME/2,andTModel2.
6.4 PractitionerExperiences
Inmid‐2003,theFloridaDepartmentofTransportation,whichatthetimewasusingTRANPLAN
asthesoftwareenginefortheFloridaStandardUrbanTransportationModelStructure(FSUTMS),reportedthefindingsofitsevaluationofnumerousmodelingsoftwarepackagesand
recommendationsforthenextiterationofitsstatewidemodel(9).ThereportconsideredmodelingsoftwarepackagesincludingVISUM,Cube/Voyager,EMME/2,andTransCADinthecontextofeachprogram’srobustness,operationalstrengthsandweakness,applicabilityto
modelinginFloridaaspartofFSUTMStoolbox,andabilitytomeettherequirementsofFlorida’sfuturemodelingneeds.Practitionersurveysprovideduseropinionsandratingsforthesoftwarepackages,andCube/VoyagerandTransCADwereshortlistedbythestudy’ssteeringcommittee
fordetailedevaluation,includingreviewofsoftwarespecificationsanddiagnosticsofvariousmodelfunctions.Ultimately,thestudy’smodeltaskforcevotedinmid‐2003toadoptTransCADinsteadofCube/VoyagerasthenewsoftwareplatformforFSUTMS.However,documentation
indicatesthatapproximatelyoneyearaftertherecommendationofTransCADandthestartofthetransitionalprocess,themodeltaskforcedecidedinOctober2004tonegotiatewithCitilabsfortheimplementationofCube/VoyagerforFSUTMS,essentiallyreversingthe2003
recommendationforTransCAD(35).SlowdevelopmentoftheTransCADengineforFSUTMSandanunsatisfactorybusinessrelationshipwiththedeveloperwerecitedasreasonsforthedecision.Currently,theFloridaDepartmentofTransportationhasimplementedandisusingCube/Voyager
forFSUTMS.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
30
TheCityofIrvineDepartmentofPublicWorks’AdvancedTransportationDivisionalsoperformedamodelingsoftwareevaluation,includingCube/VoyagerandTransCAD.RecommendationsincludedusingCube/Voyagerforshort‐termupgradestotheexistingmodelinTRANPLANand
implementationofTransCADforlong‐termnewmodeldevelopment(36).
Inrecentyears,theNorthCarolinaDepartmentofTransportation,theSouthernCaliforniaAssociationofGovernments(SCAG),andtheNorthCentralTexasCouncilofGovernment(NCTCOG)havetransitionedtheirmodelsfromTRANPLANtoTransCAD(37).TheOrangeCounty
TransportationAuthority(OCTA)usesTransCADfornewmodeldevelopment.
Currently,otherusersofCube/VoyagerincludeDepartmentsofTransportationinCalifornia,Maine,Florida,andWisconsin,andtheAtlantaRegionalCommission(ARC)inGeorgia.OtherusersofTransCADincludeDepartmentsofTransportationinOhio,Massachusetts,Michigan,
Iowa,Indiana,andtheChittendenCountyMPO(CCMPO)inVermont.Similartomanyconsultingfirms,ResourceSystemsGroup,Inc.,basedinWhiteRiverJunction,Vermont,isversedinabroadrangeoftraveldemandmodelingsoftwarepackages,includingCube,TransCAD,andVISUM(see
AppendixA:A‐6).Thisisabrieflistofactivemodelingsoftwareusersconsideringtheubiquityofthemodels,bothdomesticallyandinternationally.
TransCADisactivelyusedforplanning,studies,andresearchinVermontbytheCCMPOandtheUniversityofVermontTransportationResearchCenter.In2005,ResourceSystemsGroup,Inc.
completeda2000baseyearregionalTransCADmodelofChittendenCounty,andcontinuallymaintainsandupdatesthemodelfortheCCMPO(23).Themodelperformstraveldemandforecastsfor2005to2030atfive‐yearintervals,andisusedfortheMetropolitanTransportation
Plan(38),aswellasotherplanningstudies.Similarly,theTransportationResearchCentercurrentlyusesTransCADasananalyticaltoolforanumberofresearchprojects,includingtheNetworkRobustnessIndex:AComprehensiveSpatial‐BasedMeasureforTransportation
InfrastructureManagement(39)andTransportationImpactsofTransit‐OrientedDevelopmentinRuralTowns(40).
7. SummaryandRecommendations
Thestatewidemodelisavaluabletraveldemandforecastingandtransportationanalysistoolfor
Vermont,anditshouldbemaintained,updated,andrefinedsothatitcancontinuetoserveinthatregard.ThemodelhasbeensuccessfullyappliedtoplanningstudiesinthestateandhasanapparentroleintheLongRangeTransportationBusinessPlan,theHighwaySystemPolicyPlan,
andinairqualityanalysesforenvironmentalplanning.Withnewtransitandrailcomponents,themodelwouldalsobepositionedtocontributetothegoalslistedinthePublicTransportationPolicyPlanandtheStateRail&PolicyPlan.
Thestatewidemodelhasrecentlyundergoneaseriesofupdatesandamigrationtoanew
softwareplatformin2007,butfurtherrefinementsofthemodelwouldbebeneficial.Themodelshouldbecontinuallymaintained,includingcalibrationandvalidationprocesses,and
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
31
improvementstoitsfour‐stepalgorithmsshouldbeexplored,suchasanewmodechoicemoduleandtheinclusionofafeedbackloopbetweenassignment,distribution,andmodechoice.ThefurtherdisaggregationofitsVMTandaveragespeedoutputsshouldalsobeconsideredto
potentiallyimproveemissionsmodelingforairqualityanalyses.
Thethreetraveldemandmodelingsoftwarepackagesreviewedinthisreportmeetthecurrentrequirementsandpotentialfutureusesofthestatewidemodel.Fundamentally,theirfunctionalitiesaresimilar,butwithuniqueinterfacesandformatting,sothedecisiontouseone
insteadofotherswouldprimarilydependonuserpreferenceorconformitywithothersoftware(i.e.,anArcGISusermayprefertheGISinterfaceandoptionsofCube,andpossiblyVISUM,insteadofTransCAD).Animportantadditionalfactortoconsideristhatthereiscurrentlyabase
ofpractitionersandresearchersinVermontemployingTransCAD.
Ataminimum,thereisenoughcausefortheVermontStatewideModeltobemaintainedandperiodicallyupdatedtokeepitviableandavailableforplanningneedsatVTrans.Theoverallmodelcouldbekeptinitscurrentformwithoutsubstantialimprovements,suchastransitand
railnetworks,butshouldremainavailableforforecastsofroadwaytravelandVMTestimates.Mostimportantly,thesuccessandlongevityofthestatewidemodelgreatlydependsontheclearly‐definedproceduresandgoalsofitsutilitybyVTransandotherVermontagencies.As
statedpreviously,thegoalsofastatewidemodelingprogramshouldbedefinedwellinadvanceofmodel‐specificdetails,suchasdataneeds,modelcomponents,computersoftware,andbudgetallocation.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
32
References
1. Horowitz,A.J.,etal.NCHRPSynthesis358:StatewideTravelForecastingModels.TransportationResearchBoardoftheNationalAcademies,Washington,D.C.,2006.
2. Giaimo,G.T.andSchiffer,R.StatewideTravelDemandModeling:APeerExchange,LongboatKey,Florida,September23‐24,2004.TransportationResearchCircular,No.E‐C075.TransportationResearchBoardoftheNationalAcademies,Washington,D.C.,August2005.
3. Horowitz,A.J.andFarmer,D.D.“ACriticalReviewofStatewideTravelForecastingPractice,”TransportationResearchRecord1685,TransportationResearchBoard,NationalResearchCouncil,Washington,D.C.,1999,pp.13–20.
4. Bowman,J.L.andBen‐Akiva,M.“Activity‐BasedTravelForecasting”Activity‐BasedTravelForecastingConferenceProceedings,NewOrleans,LA,June2‐5,1996.
5. Davidson,W.,etal.“Synthesisoffirstpracticesandoperationalresearchapproachesinactivity‐basedtraveldemandmodeling.”TransportationResearchPartA:PolicyandPractice,2007,vol.41,issue5,pages464‐488.
6. Vovsha,P.,Bradley,M.andBowman,J.“Activity‐BasedTravelForecastingModelsintheUnitedStates:ProgressSince1995andProspectsfortheFuture.”InProgressinActivity‐BasedAnalysis(H.Timmermans,ed.),Elsevier,Amsterdam,Netherlands,2005,pp.389–414.
7. Vovsha,P.andBradley,M.“AdvancedActivity‐BasedModelsinContextofPlanningDecisions.”TransportationResearchRecord:JournaloftheTransportationResearchBoard,No.1981.TransportationResearchBoardoftheNationalAcademies,WashingtonD.C.,2006,pp.34‐41.
8. MetropolitanTravelForecasting,CurrentPracticeandFutureDirection,SpecialReport288.TransportationResearchBoardoftheNationalAcademies,Washington,D.C.,2007.
9. Pendyala,R.M.,etal.“EvaluationofTransportationModelsfortheStatewideModelTaskForce.”FloridaDepartmentofTransportationResearchCenter,2003.
10. VHB/VanasseHangenBrustlin,Inc.VermontStatewideTravelDemandModelImprovements:UpdatedPassengerandTruckModelsinCube/Voyager.VermontAgencyofTransportation,June2007.
11. Horowitz,A.J.,GuidebookonStatewideTravelForecasting,ReportFHWA‐HEP‐99‐007,FederalHighwayAdministration,Washington,D.C.,July1999.
12. Martin,W.A.,etal.NCHRPReport365:TravelEstimationTechniquesforUrbanPlanning.TransportationResearchBoardNationalResearchCouncil,Washington,D.C.,1998.
13. Circ‐WillistonEIS:(http://www.circeis.org/).
14. BenningtonBypass:(http://www.aot.state.vt.us/progdev/Sections/Design/bennBypass/Benn.htm).
15. WesternCorridorTransportationManagementPlan:(http://www.vtwesterncorridor.org/).
16. CambridgeSystematics,Inc.Vermont’sHighwaySystemPolicyPlan.VermontAgencyofTransportation,June2004.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
33
17. TranSystems.Vermont’sPublicTransportationPolicyPlan.VermontAgencyofTransportation,February2007.
18. ParsonsBrinckerhoff.StateRail&PolicyPlan,2006,StateofVermont.VermontAgencyofTransportation,December2006.
19. CambridgeSystematics,Inc.VTransAssetManagementVisionandWorkPlan.VermontAgencyofTransportation,June2002.
20. CambridgeSystematics,Inc.VermontLongRangeTransportationPlan.VermontAgencyofTransportation,January2002.
21. ResourceSystemsGroup,Inc.VermontLongRangeTransportationBusinessPlan,PublicReviewDraft.VermontAgencyofTransportation,October2008.
22. FinalReportandRecommendationoftheGovernor’sCommissiononClimateChange,PresentedtoGovernorJamesH.Douglas.October2007.
23. ResourceSystemsGroup,Inc.CCMPORegionalTransportationModelDocumentation:2000BaseYearModel.ChittendenCountyMetropolitanPlanOrganization,January2008.(Retrievedfrom:http://www.ccmpo.org/modeling/release_history.html).
24. U.S.EnvironmentalProtectionAgency.“EPAFindsGreenhouseGasesPoseThreattoPublicHealth,Welfare/ProposedFindingComesinResponseto2007SupremeCourtRuling.”April17,2009.www.epa.gov(Retrievedfrom:http://yosemite.epa.gov/opa/admpress.nsf/0/0EF7DF675805295D8525759B00566924).
25. PewCenteronGlobalClimateChange.“CaliforniaVehicleStandards.”www.pewclimate.org(Retrievedfrom:http://www.pewclimate.org/what_s_being_done/in_the_states/vehicle_ghg_standard‐moreinfo.cfm).
26. OfficeoftheGovernorofCalifornia.“Gov.SchwarzeneggerSignsLandmarkLegislationtoReduceGreenhouseGasEmissions.”gov.ca.gov(Retrievedfrom:http://gov.ca.gov/press‐release/4111/).
27. PewCenteronGlobalClimateChange.“StateLegislationfromAroundtheCountry.”www.pewclimate.org(Retrievedfrom:http://www.pewclimate.org/what_s_being_done/in_the_states/state_legislation.cfm).
28. VermontAgencyofNaturalResources.“AirPollutionControlRegulations,SubchapterXI,LowEmissionVehicles–RegulationstoControlGreenhouseGasEmissionsfromMotorVehicles.”November7,2005.(Retrievedfrom:http://www.anr.state.vt.us/air/htm/ProposedAmendments.htm#cars).
29. VermontDepartmentofPublicService.“VermontComprehensiveEnergyPlan2009,[An]Updatetothe2005Twenty‐YearElectricPlan,PublicReviewDraft.”May2008.(Retrievedfrom:http://publicservice.vermont.gov/planning/CEP%20%20WEB%20DRAFT%20FINAL%206‐4‐08.pdf).
30. DemocraticStaffoftheCommitteeonEnergyandCommerce.MemorandumtoMembersoftheCommitteeonEnergyandCommerce,U.S.HouseofRepresentatives,regardingmask‐upsessiontoconsiderH.R.2454,theAmericanCleanEnergyandSecurityActof2009.May16,2009.(Retrievedfrom:
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
34
http://energycommerce.house.gov/index.php?option=com_content&view=article&id=1625:chairmen‐waxman‐and‐markey‐introduce‐the‐american‐clean‐energy‐and‐security‐act&catid=141:full‐committee&Itemid=85)
31. CaliforniaAirResourcesBoard.“EMFAC2007version2.30,CalculatingemissioninventoriesforvehiclesinCalifornia,User’sGuide.”November2006.(Retrievedfrom:http://www.arb.ca.gov/msei/onroad/latest_version.htm).
32. Cube/Voyager,version5.©1999‐2008Citilabs,Inc.(http://www.citilabs.com).
33. TransCAD,version5.0.©1994‐2008CaliperCorporation.(http://www.caliper.com).
34. VISUM,version10.©1998‐2008PTV/PTVAmerica,Inc.(http://www.ptvamerica.com).
35. MinutesoftheFloridaModelTaskForceMeeting(2004).Orlando,Florida,MeetingofOctober6,2004.
36. Chen,J.X.TravelDemandModelingSoftwareEvaluation.PresentedattheSCAGModelingTaskForceMeeting,January24,2007.
37. Cervenka,K.TransCADModelingatNCTCOG:HowWeDidIt.PresentedattheFloridaModelTaskForceMeeting,November12,2003.
38. ChittendenCountyMetropolitanPlanningOrganization.2025ChittendenCountyMetropolitanTransportationPlan.Adopted,January2005.(Retrievedfrom:http://www.ccmpo.org/MTP/).
39. UniversityofVermontTransportationResearchCenter.NetworkRobustnessIndex:AComprehensiveSpatial‐BasedMeasureforTransportationInfrastructureManagement.(Retrievedfrom:http://www.uvm.edu/~transctr/?Page=022318.html&SM=Research_Submenu.html).
40. UniversityofVermontTransportationResearchCenter.TransportationImpactsofTransit‐OrientedDevelopmentinRuralTowns.(Retrievedfrom:http://www.uvm.edu/~transctr/?Page=022755.html&SM=Research_Submenu.html).
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
35
AppendixA
MeetingSummariesandCorrespondence
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
36
A‐1MeetingDate:November6,2008Location:VermontAgencyofTransportation,Montpelier,VTPartIAttendees:MaureenCarr,VTrans,TrafficOperations ([email protected],802‐828‐3091)JohnBlodgett,VTrans,TrafficOperations ([email protected],802‐828‐3972)RichardWatts,UVMTRCAndrewWeeks,UVMTRCMaureenandJohnexplainedwhattheirusualtasksareatVTrans,whichincludemanagement,analysis,andreportingofVTranscountsthroughoutthestate.Theyalsomakeprojectionsforfutureyearvolumesbasedonhistoricaltrends.Theyprovidedandexplainedsomeoftheiroffice’sAADTandseasonalvolumetrendsreports.Whenaskedhowthestatewidemodelcouldaidintheirtasks,Maureenindicatedthattheycouldmakeuseofthemodelforthefollowing:
trafficgrowthprojectionsforfutureyearprojects effectsoftrafficnetworkdisruptions,suchasdetours/re‐routingduetoabridgeclosure,
orsomeothernetworklinkloss(thisdatawouldthenbeusedfordetailedanalysesalongdetourroutesusingsimulationsoftware)
bettervolumeestimationsfor“local”roadwayclasses,whicharenotroutinelycountedTheTRCwillcoordinatewithMaureenandJohnasthestatewidemodelevaluationprogresses.PartIIAttendees:CostaPappis,VTrans,PolicyandPlanning ([email protected],802‐828‐5790)RichardWatts,UVMTRCAndrewWeeks,UVMTRCCostaprovidedthestatewidemodelfilesanddocumentationpreparedbythepreviousmodeler,includingadevelopmenttimelineofthemodel,set‐upinstructions,listsofthefilestructure,andcontactinformationofthoseinvolvedinitsdevelopmentanduse.Costadescribedsomeprevioususesofthestatewidemodel,includingenvironmentalimpactstatements(e.g.Circ‐WillistonEIS),theBenningtonBypass,theMorristownBypass,theWesternCorridorStudy,andtheStateEmployeeCommutingStudy.SimilartoMaureen’scomments,Costaindicatedaninterestinusingthemodelfordetour/re‐routingevaluationsandITS.CostasaidthatVTransneedstodevelopamodelingworkplanforthenext3‐4years,likelyaspartoftheLongRangeTransportationBusinessPlan,andwouldincluderecommendationsfromtheTRC.Costahighlightedsomeneededimprovementstothestatewidemodel:
transitnetworktoanalyzemulti‐modalalternatives
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
37
integrationwiththeCCMPOmodelshouldbeexplored,suchastransferabilityofnetworkandTAZdata;travelmodesshouldmatchthoseintheCCMPOmodelfordatacoordinationwiththeregionalmodel
preparationforpotentialnon‐attainmentinareasofVermont(theVermontDepartmentofEnvironmentalConservationcurrentlyoverseesairqualitywork,butVTranswouldneedtoperformanalysesforconformitydeterminationandtheSIPshouldnon‐attainmentoccur)
potentialfreightmodelchanges,includingarailcomponent(thisdependsontheoutcomeofVTransfreightplanRFPcurrentlyactive)
CostasaidthatsinceVTransisin“preservationmode”therewouldlesslikelybeagreatneedformodeluseinmajorcapitalimprovementstudies,butalternativelyfortransitimprovementstudies.Afterthemeeting,wespokeinformallytoGinaCampoli([email protected],802‐828‐5756)whomentionedthepotentialmodelusefortheGovernor’sClimateChangeCommission(fortransportation‐relatedpollutantandgreenhousegasemissionsandenergypolicies).TheTRCwillcoordinateprimarilywithCostaasthestatewidemodelevaluationprogresses.ActionitemsforTRC
BegintoreviewVTransstatewidemodelanddocumentation PreparedraftrecommendationsforpotentialuseandupdatesoftheVTransstatewide
model Continuemodelingsoftwarepackageevaluationandreviewofmodelingpracticesat
otherstatedepartmentsoftransportation
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
38
A‐2MeetingDate:December10,2008Location:VermontAgencyofTransportation,Montpelier,VTAttendees:ClayPoitras,VTrans,PolicyandPlanning ([email protected],802‐828‐3968)ScottBascom,VTrans,PolicyandPlanning ([email protected],802‐828‐5748)CostaPappis,VTrans,PolicyandPlanning ([email protected],802‐828‐5790) AndrewWeeks,UVMTRC
ScottismanagingtheHighwaySystemPolicyPlan,whichispartoftheMulti‐modalPolicyPlan.
Costamanagescorridorplanning,publictransitandfreightplanning,withthePublicTransportationSystemPolicyPlanandRailPolicyPlanaspartoftheMulti‐modalPolicyPlan.
Claywouldliketothinkoutside‐the‐boxaboutwhatotheragenciescouldusethemodel’soutput.ANR/DECwoulduseVMTandrelatedinformationforairqualityneeds.Note:WhataboutVermontAssociationofPlanning,DevelopmentAgencies(VAPDA)andAgencyofCommerceandCommunityDevelopment,DepartmentofPublicSafety?
ChittendenCountyiscoveredbytheCCMPOregionalmodel.Note:ForotherareasofVermont,woulditbemoreworthwhiletoisolateanddetailasectionofthestatewidemodelforregionaluse,insteadofbringingtheentirestatewidemodeltothatlevelofdetail?
TheAssetManagementPlancouldpotentiallymakeuseofthemodelforidentificationofroadwaysforfunding/workpriority–aperformancereviewofthenetworktodetermineinvestmentqueuing.Contact:BartSelle([email protected],802‐828‐2757).
ChuckGallagher([email protected],802‐828‐3889)andAlecPortalupi([email protected],802‐828‐3889)fromOperationsmayalsohaveadditionalusesforthatdivision.
Scottshowedinterestedintheideaofidentifyinga“primary”or“critical”roadwaynetworkforthestate,similartoTRC’sworkontheNetworkRobustnessIndex.Usingthestatewidemodelasananalysistoolfordeterminingcriticalroadwayscouldbebeneficial.Note:OneexamplediscussedwasapossiblebridgefailureordisasterevenalongI‐89inthevicinityofWaterbury.Whatwouldbetheregionalimpactandhowcouldtrafficbediverted?ThiswouldalsorelatetotheHighwaySystemPolicyandAssetManagementPlans.(Seealso:possiblereplacementofCrownPointBridge,NYSDOT.)
Regardingsoftwarepackages,CostaindicatedthatitwouldbeimportanttoconsiderCCMPO’spractices(i.e.TransCAD).AnotherimportationconsiderationisthatVTransusesArcGISexclusively,whichistheGISinCUBE.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
39
A‐3PhoneConversationwithClayPoitras,VTransDate:November20,2008DiscussionClay’sgeneralcommentsaboutthestatewidemodel:
Heisconfidentofthelong‐termneedanduseofthemodel.
Therewilllikelynotbemuchneedforthemodelinthenext12‐18months,buthewantstokeepitfunctionaluntilalong‐termplanforuseisdeveloped.
Althoughthemodeliscurrentahighwaymodel,therewillnotbemanybighighwaycapacityprojectsinthefuturethatwouldrequirethemodel.Theemphasiswouldbeonexistinghighwayinfrastructureimprovements.
Clayrefersthemodelas“macro”andclearlystatesthatitbecomesincreasinglylimitedinutilityasthespatialresolutionandanalysisdetailincrease
Therewillbeincreasedemphasisoncorridormanagementandplanning,suchasfor5to10‐milesegmentsofroadways,whichwouldrequireadditionalmicro‐analysiscapabilities(simulation/HCMmethodologies).Thestatewidemodelcouldpotentiallyfeedvolumestothemicro‐analyses.SeeWesternCorridorStudy.
Claycitedanumberofareasthatthemodelcouldbeapplied,perhapsnotimmediately,butatsomepointinthefuture:
Projectdevelopmentandalternativeplanning(contact:KevinMarshia,VTrans)
Airqualityanalyses,possiblenon‐attainment(contact:GinaCampoli,VTrans)
Transportationplanningassistancefortheregionalplanningcommissions(RPC)–specificallythelocaltransportationplanners;abridgedcontactlistisincluded
Corridormanagementstudies(contact:CostaPappis,VTrans);EleniChurchill,CCMPO,canbecontactedregardingtheWesternCorridorStudy
Modalpolicyplan,typicallyat5‐yeariterations(contact:ScottBascom,VTrans)
Possiblenewinterchangecapacityimprovement–I‐89nearHinesburgRd./KennedyDr.inSouthBurlington
ContinueduseforEISwork,suchasCirc‐WillistonDEIS
CollaborationwithCCMPOtosupplementspatiallimitationsoftheCCMPOmodel(contact:EleniChurchill,CCMPO)
ClaysaiditispossibletocontactJulieMurphy,VHB,withtechnicalquestionsaboutthemodel;howeverVHBisnotcurrentlyundercontractwithVTrans.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
40
Clayidentifiedthestatewidemodel’scurrentutilitylimitationsduetonotransitnetworkorrailcomponentinthefreightmodel;Costa’sfreightmodelRFPmaydealwiththelatterlimitation.
Claythoughtitworthwhiletoexplorecurrentmodelingtrends,evolution,andlikelytoolsthatwillprimarilybeusedinthecomingyears.
Clayrecognizedthathiring‐outtoconsultantsforstatewidemodelingtasks(applicationofthemodeland/ormaintenanceonthemodel)isanoption.
Claybelievesthatanimportantquestiontosetastageforthisentireevaluationis:“whyshouldtheStateofVermontandVTranscontinuewithastatewidemodel?”
Clayagreedthattheevaluationprocessismovingintherightdirection–thatweshouldcontinuetodevelopasetoflikelyusesofthemodelinthefuture,identifyanydeficienciesinthemodeltoaddressinordertofacilitatethatsetofmodeluses,andthenmakeanactionplantoaddressthosedeficiencies.
ClaysaidthatwecanprovideupdatestohimandCostaatanypointduringtheongoingprocess,inamannerofourconvenience.
ContactInformationprovidedbyClay
VTransProjectDevelopment:KevinMarshia,Roadway,Traffic&[email protected](802)828‐2664
VTransPolicy&Planning:
ScottBascom,PlanningProjectManager(Scottwillbemanagingtheupdatetothestatewidehighwaymodalplan.)[email protected](802)828‐5748
CostaPappis,PlanningProjectManager(CostamanagesourCorridorManagementStudiesandwillbemanagingthependingstatewidefreightstudy.)
GinaCampoli,AOTEnvironmentalPolicyManager(airquality&other)[email protected](802)828‐5756
RegionalTransportationPlanners:
ContactinformationforregionalplanningcommissionsandtheCCMPOisattached.SuggestconsultingEleniChurchillinadditiontoDaveRobertsattheCCMPO.Eleniismanagingthewesterncorridorstudy.Inaddition–asaformermemberofVTransandacolleague‐sheisverywellfoundedinthestatewidemodel,howitworksanditslimitations.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
41
A‐4ConversationwithEleniChurchill,CCMPODate:December09,2008attheTRCEleniworkedatVTransfor12yearsfromabout1994to2006,managingthestatewidemodel.DuringhertimeatVTrans,shecoordinatedcloselywithJulieMurphyatVHB,theon‐callconsultant,workingonthemodel.DiscussionEleni’sgeneralcommentsaboutthestatewidemodel:
Shefeelsthatitisimportanttokeepthemodelalivewithmaintenanceandupgrades,mainlyfortransitmodeling(modelimprovementsneeded,though)andpotentialairqualityneedsinthefuture,incaseofnonattainmentinVermont.
FortheWesternCorridorStudy,whichEleniismanagingatCCMPO,thestatewidemodelreceivedadditionalcalibrationalongthewesternportionofVermont,goingbeyondtheupdatesthatweredonebyVHBwhenthemodelwasbroughtintoCUBE.CharlieMarkperformedsomeofthatadditionalcalibrationwhilehewasamodeleratVTrans,andEdBromageatCambridgeSystematics,whoisrunningthemodelingfortheWesternCorridorStudy,alsoperformedmorecalibrationforwesternVermont.EleniwillrequesttheupdatedmodelfilesfromCambridgeSystematicsforTRCuse.
Sherecognizestheimportanceoftransitmodelingcapabilitiesinthemodel,andtheneedforarailnetwork,formodelingofpassengerrailandfreightrail.Agrowingdesiretoshiftmorefreightfromtrucktorailcouldprecipitateaneedforrailmodelinginthestatewidemodel.
WhileatVTrans,Eleniwasinvolvedinworktoidentifya“primarynetwork”inVermont–asetofcriticallinks/infrastructure–thatshouldreceivepriorityinfundingandmaintenance.Traveltimefromthestatewidemodelwasakeycomponentinidentifyingthe“primarynetwork,”andthemodelcouldbeusedsimilarlyinthefuture.
ElenibroughtahardcopyofVermontStatewideTravelDemandModelImprovements,VHB,June2007forTRCreference.
ElenialsosuggestedgettingintouchwithJulieMurphyatVHB.WhenVHBwasperformingthemodelupdateandmigrationintoCUBE,partorallofitwasdonefirstinTransCAD.ElenithinksitwouldbeworthwhilefortheTRCtoobtainthoseTransCADfiles.
AlsoregardingTransCADversusCUBE,Elenithinksthatitwouldbenicetohavethestateandregionalmodelallinoneplatform.She,ofcourse,recognizestheneedforaclearplanforfutureusesofthestatewidemodelbeforeworryingaboutdetailssuchassoftwarepackages.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
42
A‐5MeetingDate:March12,2009Location:VermontAgencyofTransportation,Montpelier,VTPartIAttendees:BartSelle,VTrans,PolicyandPlanning(AssetManagement)([email protected],802‐828‐2757)AndrewWeeks,UVMTRCBartbrieflydiscussedthegeneralresponsibilitiesofassetmanagementincludingthesystemsofpavement,bridges,buildings,aviation,safetyandmaintenancemanagement.
Assetmanagementhasestablishedprocedurestomeetitsplanningandpolicy‐makingneeds.Traveldemandforecastingdoesnotplayaninherentroleintheassetmanagementprocedures,sinceassetmanagementisameansforeffectiveinvestmentforexistingtransportationinfrastructure.
Asidefromthetraveldemandforecastingapplicationsofthestatewidemodel,Bartidentifiedapotentialneedforestablishingabaseconditionforlikelyperformancemeasures,includingmobility(capacities,v/candtravelspeed).ThereauthorizationofSAFETEA‐LUin2009mayidentifyaplanforstatetransportationagenciestoestablishguidingperformancemeasuresformaintenance,investment,safety,andmobilityinpolicyplanning.
Increasingemphasisonperformancemeasuresandaccountabilityforprojectapprovalandfundingmayrequiremorequantifiableanddefensiblemetricsinthedecision‐makingprocess.Thestatewidemodelcouldserveasatoolinthisregard,providingquantitativemeasuresofmobility.
PartIIAttendees:BruceNyquist,VTrans,ProgramDevelopment(Roadway,TrafficandSafety)([email protected],802‐828‐2696)AndrewWeeks,UVMTRCBrucediscussedplansforVTranstouseFHWA’sSafetyAnalystprogram(http://www.safetyanalyst.org/index.htm)toidentifyprobablehighcrashlocationsinthestate,andtheassociateddataneeds.Hesaidthattheywouldfocuspredominantlyonruralroadways,includingmajorandminorcollectorsandlocalroads.(Inthestatewidemodel,thosethreetypesareidentifiedasfunctionalclasses7,8,and9,andaccountforapproximately18,000linksinthemodelandroughly6,000milesofroadway.Trafficvolume(AADT)needsforSafetyAnalystwouldspatiallyexceedtheTrafficResearchdepartment’scurrentcollectioncapabilities.)
Furthermore,HPMSwouldnotbecapableofprovidingtheneededdata.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
43
TheAADTneedsforSafetyAnalystwouldbecurrent‐yearvolumes–theparticularyearbeingstudiedbyVTrans–andnotnecessarilyfutureyearforecasts.IfthestatewidewereusedtosupplementTrafficResearch’sAADTdatawithanalysis‐yearestimates,implementationofSafetyAnalystmaybemorefeasible,andresultinmoreaccurateestimates.Twoissueswiththestatewidemodelwouldneedtobeaddressedpriortoitsimplementationinthiscase:
Themodelprovidesbaseyearvolumesandfutureyearforecasts.Thecurrentbaseyearis2000,andthefutureyearis2020,whichwouldlikelybeupdatedto2010and2030,respectively,ifthemodelwerekeptactive.Inshort,thestatewidemodel’sanalysisyearsarenotreadilyadjustableduetoitsnatureasatraveldemandforecastingtool.However,itislikelythatVTranswouldneedAADTestimatesforSafetyAnalystforananalysisyearbetweenthestatewidemodel’sbaseyearandforecastyear.Asasolution,aprocedureforinterpolationbetweenbaseyearvolumesandfutureyearvolumeswouldbeneeded,toarriveatvolumeestimatesfortheanalysisyearbeingevaluatedinSafetyAnalyst.
Thedirectuseofvolumeestimatesfromthestatewidemodel,insteadofageneralcomparisonofforecastedvolumeestimatestothebaseconditions,raisestheissueofthemodel’saccuracy.ThisissuewaspreviouslyraisedduringthediscussionwithTrafficResearchinNovember2008.ThiswasalsoidentifiedbyaformerVTransmodeler.Updatedcalibrationandvalidationofthemodelwouldlikelyberequiredtoensurethemodel’saccuracy.Itisalsoprobablethatadditionalrefinementofthemodel’svolumeestimatescouldalsobenecessarybeforebeingusedinaprogramsuchasSafetyAnalyst.Thequestionthenbecomes:isthiseffortworththevolumeestimatesfromthemodelforuseinSafetyAnalyst,orwoulditbemorefeasibletouseamorebasic,butmoreeasilyestimatedandchecked,proceduretoestimatetheneededAADT?
Inadditiontosupplementingvolumedatacollection,alsohavinganinventoryofbaseyearconditionsformobilitymeasures,suchascapacities,v/candtravelspeedscouldbehelpfulforprojectevaluation.Inthisregard,themodelwouldnotbereliedonforforecastedvolumesforfutureyears,butinsteadasatooltobetterdefinebaseyearhighwayconditionsinVermont.Thisobjectivemaynotbeanappropriateapplicationofthecurrentmodel,sinceitismeantasaforecastingtoolforcomparisonoffuturevolumestobaseyearvolumes,orcomparisonofplanningalternatives.However,thepossibilityofemployingthemodelasadataresourceforsafetyanalysesandperformancemeasuredeterminationswouldbenefitVTransdataneedsandobjectiveswhilekeepingthemodelrelevant.
Otheruses:thestatewidemodelisgenerallynotapplicablefortrafficoperationsandproject‐levelanalyses.Thisisthecaseformostmacroscopicstatewidemodels,notjustVermont’s.However,althoughindividualprojectsarenotevaluatedusingthestatewidemodel,theneteffectofdevelopmentandgrowthduetonumerousprojectsinanareacouldbequantifiedusingthemodel(e.g.St.AlbansRoute7corridor).Thisprocedurecouldprovideguidanceinthereviewprocessofdevelopmentprojects.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
44
Otheruses:therearenomajorroadwayprojectsplannedorunderanalysisthatwouldrequirethestatewidemodel.ThemodelhasbeenrecentlyemployedfortheCirc‐WillistonEIS,andcurrentlyfortheWesternCorridorStudy,buttherearenoclearusesformajorroadwayplanninginthenearfuture.
SummaryComments–TheStatewideModelasaDataResource
AcommonthreadinthediscussionswithBartandBrucewastheneedformoretrafficdata,bettertrafficdata.Certainlythecostsandresourcesrequiredtogathertransportationsystemdatainthefieldaresignificant.Itissimplynotpracticaltogatherabroadsetofdatatypes(volumes,speeds,delays,geometryandcontrol,etc.)atalllocations,andcontinuouslyfortrafficconditions.
NCHRPReport446,AGuidebookforPerformance‐BasedTransportationPlanning(TransportationResearchBoard–NationalResearchCouncil,2000)identifiesurbanandstatewidetraveldemandmodelsasusefultoolstosupplementfield‐collecteddataforperformance‐basedevaluationsandplanning.Importantly,however,thereportidentifiestheneedformodelcalibrationwithsurvey/fielddataonaregularbasisinorderforthemodelstoprovideaccurateestimatesofcurrent/baseyeardata.
SoftwareemployedbyVTransfortransportationnetwork/systemevaluationsthatrequireextensivedatainventoriesincludeSafetyAnalyst,asmentionedbyBruce,andHighwayEconomicRequirementsSystem–State(HERS–ST),whichisanassetmanagementtoolprovidedbytheFHWA(http://www.fhwa.dot.gov/infrastructure/asstmgmt/hersindex.cfm).TheRoadwayAssetManagementUnitcitessuchdatainventoriesforSafetyAnalystandHER–STaspartofitsmission.(http://www.aot.state.vt.us/progdev/Sections/Design/Design.htm).Furthermore,theVermontHighwaySystemPolicyPlan(Section5.0pages5‐6and5‐7,andAppendixB)recommendsanevaluationofthefeasibilityofexpandingtheHighwayPerformanceMonitoringSystem(HPMS)datasettomeettheneedsofHERS–STinVermont.
TheOregonDepartmentofTransportationandtheTexasTransportationInstitutehaveworkedjointlytoexploretheuseofHERS–STinassetmanagementprograms,evaluatingitsdataneedsandpotentialforimplementationwiththeODOTstatewidemodel.Theirworkhasidentifiedtheneedformorerobustdatasources,whichcanbeaconsiderablechallengewhenapplyingtheHERS‐STmodel(http://mobility.tamu.edu/resources/odot_op_perf_measures.pdf;http://www.fhwa.dot.gov/infrastructure/asstmgmt/dior09.cfm).
ThestatewidemodelcouldbecomeavaluabletoolforProgramDevelopment,specificallytheRoadwayAssetManagementandTrafficandSafetygroups,toprovidedataforthedeterminationofperformancemeasures.Importantly,inorderforthestatewidemodeltobeeffectiveinthismannerandtoensurethatitsvolumeestimatessufficientlyaccurate,itwouldrequirefrequent,regularupdatestoitsbaseyeardataandcarefulcalibrationandvalidation.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
45
A‐6EmailfromStephenLawe,RSGInc.Date:November11,2008ThefollowingisanemailfromStephenLawe,answeringquestionsabouthisexperienceandfeelingsaboutthetraveldemandmodelingsoftwarepackagescommonlyusedatRSG:
WhichtraveldemandmodelingsoftwarepackagesdoesRSGfrequentlyuse?
Fortraveldemandmodelsweusemostifnotallofthecurrentlyavailablepackages.Thelistbelowincludesnewsoftwareandsomeoldersoftwareaswell:TransCAD,CUBE,VISUM,QRS,TModel,TRANPLAN,TRANSIMS,EMME/2,aswellasapackagecalledITM(integratedtravelmodel)whichIwrote.Wealsouseseveralmicro‐simulationpackagesbutIwillnotbotherwiththosehere.
ApproximatelyhowmanyyearshasRSGusedeach?
NowIwishIhadmadeashorterlist:
TransCAD=sincetheearly1990’s.WewereabetatesterforoneoftheveryfirstversionsofTransCAD.
CUBE=sincethelate1990’s(notethatthisstartedwithTRIPS,TP+,Voyager–allofwhichwewereusingaroundthattime).
VISUM=around2005andwedon’thavesignificantexperiencewithVISUM. QRS=wehavebeenusingthisonandoffforyearswhenourclientsrequestit.Probably
mid1990’swasoneofthefirstuses.Wehadarecentprojectin2004whereweusedQRS.
TModel2=thisisnowlargelyoutofservice.Weuseditareasonableamountstartinginthelate1980’s
TRANPLAN=wehaveastatewidemodelforFloridarunninginTRANPLANrightnow.Weknowthedeveloperofthispackagewellsowecanmodifythecodetomeetspecificneeds.Weprobablyfirstusedthisintheearly1980’s.
TRANSIMS=wefirstusedthisin2006–itisstillreallyindevelopmentandnottobetakenlightlyifbeingconsideredforimplementation.
EMME/2=thisisanotherpackageweusedalongtimeagoforalittlewhile.IknowtherearestillversionsouttherebutIthinkthisisalsobeingphasedout.Weprobablyuseditinthelate1980’s.
ITM=thisisapackageIfirstwrotein1992andplayedwithovertheyears.Iwroteitwhenwewerenotsatisfiedwiththecapabilitiesofotheravailablepackagesandwewantedcontrolofthecodebase.Ihavenottouchedthisinabout3years.
Ofthosepackagesbeingused,hastherebeenashiftinsoftwarepackagepreferenceatRSG?
WhenourclientsallowustochooseweprimarilychooseeitherTransCADorCUBE.IalsolikeVISUMbutwehavehadlessopportunitytouseit.Keepinmindthatmanystateshavealreadymadetheirchoiceofsoftwaresowearesomewhatlimitedinourabilitytochoose.IliketheGIScapabilitiesinTransCAD.Itsmostfrustratingfeatureishowithandlestransitnetworksandalsohowsomeofthematricesareexposedtotheprogramminginterface(GISDK).CUBEisslightlymoreutilitarianbutisalsoagoodpackage.Iliketheinterfaceandtheintegrationwithgeodatabases.Themostfrustratingfeaturetomeistheassumedrequiredloopingintheprogramminginterface.
VermontStatewideTravelDemandModel–APreliminaryEvaluation
UVMTRCReport#10‐007
46
Havenew/inexperiencedmodelersatRSG(ifany)masteredcertainsoftwarepackagesmorequicklythanothers?Oristherenodiscernibledifferenceinthesoftwares'learningcurves?
Idon’tthinkIhavenoticedabigdifference.Onceyouunderstandwhatthealgorithmsaredoing,pickingupanewsoftwarepackageisreasonablytrivial.Iwouldcertainlynotcallthepackagesintuitivetoanon‐modelerbutIalwaysfeelthatit’stheconceptsratherthanthesoftwareitselfwhichisthelimitingfactor.Infact,thesoftwareoftengivespeopleasensethattheyknowmoreaboutmodelingthantheyactuallydowhichcanbedangerous.
Haveyouhadsufficientsupportfromthesoftwarevendors/developerswhenneeded?
Notreally.Ithinkthisisbecausewearenotaskingtrivialquestions.Usually,weareexposingabuginthesoftwareoraskinghowtodosomethingthatisratheruncommon.ItoftentakessometimetohearbackeventhoughIknowmostofthetechpeoplereasonablywell.Havingsaidthis,Idon’tknowthatthisexperienceisreallyapplicabletopeopleaskingmorecommonquestions.
Whattypesofprojects/useshaveyouemployedvariousTDMmodelingsoftwarepackagesfor?
Well,thereareseveralwaystoanswerthis.Geographically,wehavemodeledareasassmallaspartsofatownandaslargeasthestatesofFlorida,GeorgiaandUtah.Substantively,wehavemodeledroadwayinfrastructure,transitplanning,environmentalissues(airquality,globalclimatechange,waterquality,etc.),impactsonlanduse,environmentaljusticeissues,congestionpricing,andMPOandStatelongrangeplanningexercisesjusttogettheliststarted.
Top Related