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  • LosAngelesCountyMetropolitanTransportationAuthority

    BicycleTravelDemandModel

    PhaseIIModelDescription

    StaffWorkingPaperUpdate2014March

    LosAngelesCountyMetropolitanTransportationAuthorityCountywidePlanningandDevelopmentDivisionStaff:ChaushieChu,RobertCalix,RobertFarley,YingZhu,FalanGuan,JimZhang,JohnStesney,OwenMo.

    3/26/2014 1

    CambridgeSystematics,Inc.(Consultant)Staff:TomRossi,MichaelSnavely,KimonProussaloglou,Feng Liu,MoniqueUrban

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    Acknowledgement:

    TheLosAngelesMetroBicycleModelDevelopmentTeamwishestothankmembersoftheAdvisoryPanelfortheiradviceandtimetheyinvestedinhelpingusdevelopthescopeofworkforPhaseIIoftheBicycleModelDevelopmentProject.

    Specifically,wewouldliketothankJenniferDillforherinputonchoicesetlabelingandinclusionofterrainvariablesinutilityspecification;PeterFurthforhisbehavioralinsightinlowstressbicycling;SusanHandy(andKevinKrizek)fortheirfindingsthroughstatedpreferencesurveys;ThomasGotschi forhisadviceondevelopingamodelthatissensitivetothefullspectrumofbicycleinvestmentpolicies;JeremyRawforhispersonalencouragementanddiscussionsonmodelstructureandpathbuilding;DavidOry forhisrecommendationtoprioritizeourlimitedresourcesonrelevantdatacollectiontasksandexploringtheopportunitiesofmodeltransferfromothermunicipalities;andBillSteinforhisconceptualadvancementofthemodelrunstream.

    Inaddition,wealsoliketothankElizabethSallandhercolleaguesatSanFranciscoCountywhosharedtheirmostrecentfindingsonchoicesetgeneration,utilityspecification,CycleTracksdatabaseapplicationsandmodelvalidationwithus.WearealsoindebtedtoPeterVovshaandShlomoBekhorfortheirinsightfuldiscussionsonmathematicalstructurestoovercomepathoverlappinginpathchoicemodeling.

    Note:

    TheLosAngelesMetroBicycleModeliscurrentlyunderdevelopment.Thestatementsinthisdocumentrepresentasnapshotintimeoftheintentions forthatmodel.Furtherresearchmayuncoverinformationthatmightchangethemechanicsoreventheapproachofthemodel.Thefinalmodelcoulddiffersubstantiallyfromtheexamplesinthisdocument.

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  • TableofContents

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    A. FlowChartB. SupplySideInputsC. DemandSideInputsD. PathOptions RiderArchetypesE. BicyclePathChoiceModelF. IntegrationwithMotorizedTravelDemandModel Aggregation

    ProcessG. ValidationH. NextSteps

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    2. Summarize Paths

    (R)

    (i) ASCII files of 5 paths for each trip

    interchange[MD, MT,

    PF, PT, MS paths]

    (ii) Utility function

    attributes for five paths

    (I) System User

    Benefit, maximum

    biking utility (log SUM)

    1. Generate Bicycle Paths (Cube)

    [5 path types: Minimize Distance (MD), Minimize Turns (MT), Prefer Bike Facilities (PF), Prefer

    Bike Trails (PT), Minimize Stress (MS).

    3. Path Choice Model

    (R)[Cross Nested

    Logit with 5 paths & max of

    31 nests]

    (III) Bicycle volumes

    in roadway network

    (II) TAZ level Mode

    shares : auto,

    transit, walk and bicycle

    trip tables

    (iii) Path Overlap

    Matrix (up to 31 cells)

    5. TAZ Level Mode Choice

    Model (Nested Logit)

    (v) Path shares for

    each interchange

    6. Load Bicycle Trips to Network

    END

    (iv) Path-Link

    Sequence Table

    4. Aggregation Model

    [Intra-zonal, Short Distance Inter-zonal, Long Distance Inter-zonal, Pseudo zone.]

    (vi) TAZ level

    aggregate bicycle utility

    (log SUM)

    Back to #1 if bicycle

    trip assignment

    required

    Externalinputs

    Internaldatafiles

    Computationalmodules

    Modules in Times Roman Italic font only apply to bicycle trip assignment.

    Five Modules in shaded area are data & computations on TAZ level.

    Notes:

    A.FlowChart

    A. Supply Data: TeleAtlas Network

    in Generalized Cost Measurement

    (ESRI Database)

    B. Demand Data: 2,268 TAZ, 500 Pseudo

    zones, 109,572 Split blocks, TAZ level trip

    tables

    C. Utility Functionfor path choice

    D. Utility Functionfor mode

    choice

    E. TAZ Level Motorized

    Mode ChoiceModel Inputs

    Onl

    y fo

    r trip

    as

    signm

    ent

    Outputfiles

  • TheflowchartfortheproposedBicycleTravelDemandModel(BTDM)isdepictedontheleftpage,consistingoffourcategories:(1)ExternalInputs,(2)ComputationalModules,(3)InternalDataFiles,and(4)OutputFiles.Anoverviewisprovidedherein.

    ExternalInputs.Thiscategoryincludesfivecomponents.Thefirst(A)isacompleteTeleAtlasroadwaynetworkofLosAngelesCounty.Thisnetworkreflectsallroadwayfacilitiesavailabletobicycleridersin2007.ThiswasdownloadedfromESRIandwasenrichedwithdirectionallinkattributessuchasfacilitytypes,up/downslopes,numberoflanes,averagedailytrafficandspeedlimit.Thesecond(B)isadatabaseof109,572SplitCensusBlocks(SCB).ItcontainspopulationandjobswithineachSCB.AggregationindicesareavailabletogroupSCBstoCensusBlocks,CensusTracts,TrafficAnalysisZones(TAZ),88Citiesand9SubregionsinLosAngelesCounty.Thethird(C)ismathematicalexpressiontoquantifythedisutilityofbicyclepaths.Thefourth(D)andfifth(E)aremodechoicemodulestolinktheproposedbicyclesubmodelwiththeexistingCountywidemultimodaltraveldemandmodel.

    ComputationalModulesandOutputFiles.Therearesixcomputationalmodules.Thefirstisanetworkroutingscript(1) thatgeneratesfivebicycleroutetypesoreigen paths(i).Thesecond isaroutesummarizationscript(2) whichtracesthebikepaths (i) andtabulatesattributessuchasmileagebyfacilitytype,trafficvolume,lengthofupslopesandnumberofturnsalongthepath(ii),aswellasthedegreesofoverlappingamongthefivebicyclepaths(iii).BothofabovemodulesarecodedinArcGIS.ThethirdmoduleisaCrossNestedLogit(CNL)model(3).Itreadsutilityattributes(ii) andpathoverlapmatrix(iii),thencomputeschoiceprobabilitiesamongthefivebicyclepaths (v)andthelogSUMofdenominatorintheCNLmodel.ThelogSUM(I)isviewedasgeneralizedcostorexpectedmaximumutilityamongthefivebicyclepaths.ThedifferenceoflogSUM betweentwomodelruns(e.g.,NoBuildvs.Buildalternatives)isdefinedbyFederalmodelingguidelinesastheTransportationSystemUserBenefit(TSUB)generatedbytheBuildalternative.Thefourthisanaggregationmodule(4) thataggregatestheSCBlevellogSUMstoTAZlevel.TheresultantaggregatelogSUM (vi),whichreflectsthegeneralizedcostsofbicyclemode,isinputtoexistingCountywidemodechoicemodel.ThefifthisarefinedversionofexistingCountywidemodechoicemodel(5),operationalattheTAZlevel,thatoutputsthemodalsharesofprivateautomodes(drivealone,sharedride,carpool),transitmodes(commuterrail,urbanrail,premiumbuses,localbuses,etc.)andnonmotorizedmodes(walk,bicycle)(II).

    OrdinaryModelApplications.Theabovecomponentsareabletoproduceacompletesetofmodeloutputsthatanswersmostofthequestionsaskedbydecisionmakersregardingtransportationinvestment.Forinstances,Howwillthesharesofnonmotorizedmodesbeincreasedduetoinvestmentinbicyclefacilities?HowwilltheinvestmentreduceautomobileVMTsandpollutant?Howwilltheinvestmentincreasetransitridership?HowmuchTSUBwillbeproducedbythebicycleinvestment?Whatratiosofcosteffectivenessand/orcostbenefitwillbeachievedbyspecificbicycleinvestment?

    Assignment.However,ifaplanneristoanswerHowmanybicycleridersareexpectedtouseaspecificbicyclepathorbikelane?,thenanassignmentprocessisneeded.Thisprocessinvolvesgenerationofpathlinksequencetable(iv)byComputationalModule(2)andtheretentionofpathchoiceprobabilitiesforeachinterchangesonSCBlevel(v),andatripassignmentmodule(6) toassignindividualbicycletripstotheentirebicyclenetwork.

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    B.SupplySideInputsExhibitB1

    ExhibitB2

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    ThefundamentalelementforthesupplysideinputsisadetailednetworkthatreflectsallthefacilitiesthatarerelevanttobicycleridersintheCountyofLosAngeles.Thisdatabaseshouldcontainnotonlythemainroadsandlocalstreets,butalsothebackalleysandtrails.WeinitiallyconsideredtheThomasBrothersMaps(TBM)database.However,afteraseriesoftests,wedeterminedthattheTBMdatabasewasnotaccurateenoughforroutemodeling.Itoftenconnectsroadwaysofdifferentelevationsintoanerroneouspath,whichiswhyweexploredalternatives.

    TeleAtlasBaseNetwork.The2007versionofTeleAtlasnetworkwasdownloadedfromESRI.ItisahighlyaccurateanddetailedroutablenetworkbeingusedbyTomTom forrealtimeGPSnavigations.Thisdatabasecontainssixgeneralcategoriesofroadwayfacilities.Themileageofthesesixcategoriesarelistedbelow:

    1. Freewaysandfreewayaccessramps(2,160miles) 5%2. Statehighways(444miles) 1%3. Surfacestreetramps(891miles) 2%4. Primaryroads(5,245miles) 13%5. Secondaryroads(1,537miles) 4%6. Minorstreets(29,625miles) 75%

    Total(39,902miles) 100%

    ExhibitB1showsthe39,902milesofroadwaynetworkfortheentireCountyofLosAngeles.ExhibitB2showsthesamemapzoomedintotheWestsidesubregion.InExhibitB2,wecanseethatthehighestdensitiesofminorstreetsarefoundinareasof(1)vicinityofWilshireBoulevard,betweenRobertsonBoulevardandSantaMonicaBoulevard;(2)SouthLosAngeles,southwestofFreewayI110andI10nearUniversityofSouthernCalifornia;and(3)theentireCityofSantaMonica.Theseareasareshadedinyellow.

    Enhancement:BicycleFacilities.TheTeleAtlas databaseisenhancedwithbicyclefacilitiesinthreedifferenttypesoftreatments:313milesofbicycletrails(Class1),762milesofbicyclelanes(Class2),and572milesofbicycleroutes(Class3).Otheremergingdesignsofbicycletreatment,suchascycletracks,currentlyoperationalinLongBeach,willbeaddedtofutureupdatesofthedatabase.

    Besidesfreewaysandfreewayramps,allroadwayfacilitiesandbicycletreatmentsinthedatabasearemadeavailabletotheBicycleModelforpathbuildingandpathassignmentprocedures.

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    B.SupplySideInputs

    RoadwaySlopestoReflectPedalingEffort

    ExhibitB3

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    Westside

    ExhibitB4 ExhibitB5SanG

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