Post on 06-Feb-2020
THE EFFECTS OF RESIDENTIAL OFF-STREET PARKING AVAILABILITY
ON TRAVEL BEHAVIOR IN SAN FRANCISCO
A Planning ReportPresented to
The Faculty of the Department ofUrban and Regional Planning
San José State University
In Partial Ful�illmentOf the Requirements for the Degree
Master of Urban Planning
By
Alyssa B. Sherman
May 2010
THE EFFECTS OF RESIDENTIAL OFF-STREET PARKING AVAILABILITY ON TRAVEL BEHAVIOR IN SAN FRANCISCO
A Planning Report
Presented to
The Faculty of the Department of
Urban and Regional Planning
San José State University
In Partial Fulfillment
Of the Requirements for the Degree
Master of Urban Planning
By
Alyssa B. Sherman
May 2010
AcknowledgmentsManythankstomyfamilyandtoPaul’sfamilyfortheirconstantsupport,encouragement,andguidance:Mom,Dad,Jared,Grandma,Paul,Diana,Sara,andGeorge.Also,thankstomyclassmates,friends,andcolleaguesfortheirgeneroushelpwiththesurvey:
o JeanCaseyo AimeeEscobaro AnneKoellero RossNakasoneo GregNewmarko DanPesaturoo MattPiveno WendySabow
Thankstomyadvisor,DayanaSalazar,forherhelpfulreviewoftheprojectatallstages.
TableofContentsIntroduction............................................................................................................................1TheCityofSanFranciscoinContext ................................................................................................................................. 1ThePracticalRelevanceofThisStudy.............................................................................................................................. 3AbouttheSurveyMethods .................................................................................................................................................... 4DescriptionofReportOrganization .................................................................................................................................. 4AnOverviewofCurrentParkingPolicyPractice.......................................................................5Introduction................................................................................................................................................................................. 5MinimumParkingRequirements ....................................................................................................................................... 5MaximumParkingRequirements....................................................................................................................................... 7
AHistoryofParkingPolicyinSanFrancisco ...........................................................................111906‐1955:SanFranciscoBeforeMinimumParkingRequirements .............................................................. 111955‐1997:TheEraofParkingMinimums................................................................................................................. 111997andBeyond:DiscardingResidentialParkingMinimumsandIntroducingMaximums ............... 12
LiteratureReview..................................................................................................................15Introduction.............................................................................................................................................................................. 15MainThemesandDebates.................................................................................................................................................. 15Thenegativeeffectsofminimumparkingrequirements....................................................................................... 15Howavailabilityofanoffstreetresidentialparkingspaceinfluencestravelbehavior .......................... 17Howavailabilityofaparkingspaceatthedestinationinfluencestravelbehavior................................... 18Howlanduseinfluencestravelbehavior ...................................................................................................................... 18Theimpactofparkingrequirementsonurbandesign ........................................................................................... 19Theimpactofparkingrequirementsonhousingaffordability........................................................................... 20Developers’perceptionsofparkingrequirements.................................................................................................... 21Thepublic’sperceptionsofresidentialparking......................................................................................................... 22Alternativestominimumparkingrequirements....................................................................................................... 23
ConclusionsFromtheLiterature..................................................................................................................................... 25
ASurveyoftheInfluenceofResidentialParkingAvailabilityonTravelBehavior ...................27SurveyMethodology.............................................................................................................................................................. 27SurveyInstrument................................................................................................................................................................... 28SampleSelectionandSurveyAdministration............................................................................................................. 28
SurveyResults.......................................................................................................................................................................... 31StatisticalAnalysis ................................................................................................................................................................. 32InSanFrancisco,towhatextentdoestheavailabilityofanoffstreetresidentialparkingspaceinfluenceresidents’travelbehavior? .............................................................................................................................. 32Willreducingresidentialoffstreetparkingrequirementsencouragepeopletodriveless? ................. 36Dopeopleselfselecttoliveinplacesthatallowthemtotravelinacertainpreferredway? ............... 37
Conclusion ............................................................................................................................39StudyFindings ......................................................................................................................................................................... 39LimitationsoftheStudy....................................................................................................................................................... 39PolicyImplicationsoftheResearch................................................................................................................................ 39OpportunitiesforFutureResearch................................................................................................................................. 40Appendices ...........................................................................................................................41
Glossary ................................................................................................................................43
Bibliography..........................................................................................................................45
ListofFiguresandTablesTable1.MaximumParkingAllowancesinSanFrancisco ....................................................................13Table2.Locations,Dates,Times,andSampleSizeofInterceptSurveyAdministrations......29Figure1.MapofSurveyRespondentsandAreaswithParkingMaximumsinSanFrancisco.
..............................................................................................................................................................................30Table4.DemographicsofSurveyRespondents .......................................................................................31Table5.Off‐StreetResidentialParkingandPrimaryCommuteModeCross‐Tabulation ......33Table6.Off‐StreetResidentialParkingandPrimaryEntertainmentModeCross‐Tabulation
..............................................................................................................................................................................33Table7.Off‐StreetResidentialParkingandPrimaryCommuteModeStatisticalSignificance
..............................................................................................................................................................................34Table8.Off‐StreetResidentialParkingandPrimaryEntertainmentModeStatistical
Significance .....................................................................................................................................................34Table9.Off‐StreetResidentialParkingandPrimaryErrandModeCross‐Tabulation............34Table10.Off‐StreetResidentialParkingandPrimaryErrandModeStatisticalSignificance
..............................................................................................................................................................................35Table12.DescriptiveStatisticsforWorkModeShareandAvailabilityofaParkingSpaceat
Home..................................................................................................................................................................35Table13.RelationshipBetweenParkingMaximumsandNumberofTripsPerDaybyMode
..............................................................................................................................................................................37Table14.WhyPeopleChoseTheirHousingLocation ...........................................................................38Appendix1.SurveyInstrument.......................................................................................................................41
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IntroductionForyears,ithasbeenstandardpracticeforcitiesacrossthecountrytorequire
developerstoprovideaminimumnumberofparkingspaceswhenbuildingnewresidentialdevelopments.Althoughthesepolicieswereintendedtopreventspilloverparkingonthestreetandtorespondtomarketdemandforresidentialparking,inrecentyearsithasbecomeapparentthatminimumparkingpoliciessubsidizethecostofusingsingleoccupantvehiclesandencouragepeopletousevehicles.ThewidespreaduseofsingleoccupantvehiclesintheUnitedStateshasbeentiedtoincreasesinpollution,sprawl,housingprices,andunpleasanturbanaesthetics.
Toencouragepeopletodrivelessandtotaketransitorwalktotheirdestinationsmoreoften,denseurbanareasthatarewell‐servedbytransit,suchasSanFrancisco,arebeginningtoreducetheamountofresidentialparkingthatdevelopersarerequiredtoprovideoutofabeliefthatdensityandtheavailabilityoftransitinsuchareasreducesresidents’needforavehicle.SanFranciscorecentlyimplementedparkingmaximums,whichreplaceminimumparkingrequirementswithalimitonthenumberofparkingspacesthatdeveloperscanbuildincertaindenseneighborhoods.
Atthispoint,thereislittleinformationavailabletodescribetheeffectsofreducedparkingrequirementsonpeoples’travelbehavior.Thus,urbanplannerswhoareconsideringinstitutingparkingmaximums,reducingparkingminimums,eliminatingparkingminimums,orimplementinganyotherprogramtoreducethenumberofoff‐streetresidentialparkingspacesprovidedwithnewdevelopmentinSanFranciscoorelsewherearelikelytobeinterestedinhowsuchpolicieswilleffecttravelbehavior.
Todeterminetheeffectsofreducedparkingrequirementsontravelbehavior,asurveywaspreparedanddatawascollectedandanalyzedtoanswerthefollowingquestions:
1. InSanFrancisco,towhatextentdoestheavailabilityofanoff‐streetresidentialparkingspaceinfluenceresidents’travelbehavior?
2. Willreducingresidentialoff‐streetparkingrequirementsencouragepeopletodriveless?
Thestudyalsoanalyzesdifferencesinthetravelbehaviorofpeoplewholiveinareaswithparkingminimumsandareaswherethecityhasrecentlyintroducedparkingmaximumsandeliminatedparkingminimums.Italsoprovidesanoverviewofcurrentparkingpoliciesintendedtoreducemotorvehicletrips.Thisstudyproducesdatathathelpspredictwhetherpoliciesaimedatreducingresidentialoff‐streetparkingrequirementswillbeeffectiveinencouragingpeopletodriveless.
TheCityofSanFranciscoinContextSanFranciscoisacityof808,9761residentslocatedinNorthernCalifornia.Located
atthetipofapeninsula,SanFranciscoisborderedbythePacificOceantothewestandtheSanFranciscoBaytothenorthandeast.Itislocatedatthecenterofthenine‐countyBayArearegion,withSiliconValleyapproximately35milestothesouth,thecitiesofBerkeley
1U.S.CensusBureau,“PopulationFinder,”http://factfinder.census.gov/servlet/SAFFPopulation(accessedAugust30,2009).
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andOaklandtotheeast,andthescenicandagriculturallandsofMarin,Napa,andSonomacountiestothenorth.
InadditiontoitsgeographicpositionatthecenteroftheBayArea,SanFranciscoisalsotheregion’shubofemployment,shopping,entertainmentandtransportation.In2008,573,124peoplewereemployedinSanFrancisco,2andin2005thecityhad$13.03billionintaxablesales.3Therearemorethan150venuesandeventsspacesinthecity,includingtheatres,musicclubs,galleries,andmeetingspaces.4
SanFranciscoalsoenjoysthedistinctionofbeingoneofthemostexpensivehousingmarketsintheUnitedStates.5InJanuaryof2010,themediansalepriceforsingle‐familyhomesinSanFranciscowas$720,000,and$599,000forcondos.6In2007,theaveragehouseholdsizewas2.3,andthemedianannualhouseholdincomewas$65,519.7
Thecityishistoricallywell‐servedbytransit.Cablecarshavebeenoperationalsince1873,8andtodaythecountry’sseventhlargesttransitsystem‐MunicipalTransportationAgency(MUNI)–operateselectricstreetcars,lightraillines,anddieselandelectricbusesinadditiontothecity’siconiccablecars.9BayAreaRapidTransit(BART)isaregionalrapidrailsystemthatmaintainseightstationsinSanFranciscoandconnectsthecitytoBerkeley,Oakland,Fremont,SanFranciscoAirport,andsuburbanareasoutsidethecity.CaltrainisaheavyrailsystemthatconnectsSanFranciscowithSanJoseandSiliconValley.Inaddition,ferrylinesconnectSanFrancisco’sdowntownEmbarcaderotoMarin,Solano,andAlamedacounties.
AlthoughavarietyoftransitresourcesareavailableinSanFrancisco,mostofthecitywasdevelopedaftertheadventoftheautomobileinanauto‐orientedpattern.Parkingrequirementsforresidentialdevelopmentswereintroducedin1955.DespitethewideavailabilityoftransitinSanFrancisco,themajorityofcityresidentsowncars.TodayinSanFrancisco,70.3%ofhouseholdshaveatleastonecaravailable10,andamongworkers,39.6%drivealonetowork,32.2%usepublictransportation,and9.5%walktowork.11However,therearenoexistingstatisticstomeasurethetravelbehaviorofpeoplewitharesidentialparkingspaceasopposedtothosewithoutaparkingspaceathome.63.5%of
2U.S.BureauofLaborStatistics,“QuarterlyCensusofEmploymentandWages,”http://data.bls.gov/cgi‐bin/surveymost(accessedAugust30,2009).3CaliforniaDepartmentofFinance,“Financial&EconomicData,”under“SanFranciscoCountyProfile,”http://www.dof.ca.gov/HTML/FS_DATA/profiles/pf_home.php(accessedAugust30,2009).4Yelp,“VenuesandEventSpaces,”www.yelp.com(accessedAugust30,2009).5SustainLane,“2008USCityRankings:HousingAffordability,”http://www.sustainlane.com/us‐city‐rankings/categories/housing‐affordability(accessedAugust30,2009).6RosenConsultingGroup,“MarketFocus:AMonthlyAnalysisoftheSanFranciscoRealEstateMarket,”February2010.7U.S.CensusBureau,2005‐2007AmericanCommunitySurvey,“FactSheet:SanFranciscoCounty,California,”http://factfinder.census.gov(accessedSeptember20,2009).8SanFranciscoCableCarMuseum,“CableCarHeritage,”http://www.cablecarmuseum.org/heritage.html(accessedAugust30,2009).9SanFranciscoMunicipalTransportationAgency,“AboutUs,”http://www.sfmta.com/cms/ahome/indxabmu.htm(accessedAugust30,2009).10U.S.CensusBureau,“SanFranciscoCounty,California:SelectedHousingCharacteristics2005‐2007,”http://factfinder.census.gov(accessedAugust30,2009).11U.S.CensusBureau,“SanFranciscoCounty,California:SelectedEconomicCharacteristics2005‐2007,”http://factfinder.census.gov(accessedAugust30,2009).
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thecity’shousingstockwasbuiltpriorto1949,12whichmeansthereareanumberofunitsinthecitythatwerebuiltwithouttheamountofparkingthatisrequiredunderSanFrancisco’sparkingpoliciestoday.Inotherwords,thereareplentyofresidencesinSanFranciscowithoutoneparkingspaceperunit.Thus,thecity’sdevelopmentpatternprovidesanopportunitytostudythedifferencesintravelbehavioramongthoseresidentsthathaveaparkingspaceandthosethatdonot.
ThePracticalRelevanceofThisStudyThisstudypresentsnewlycollectedsurveydatacomparingthetravelbehaviorof
peoplewithorwithoutanoff‐streetparkingspaceinareaswithandwithoutparkingminimumswithinthesamecity.Thisdataprovidesinsightintowhetherpoliciesthatdiscouragevehicleownershipsuchasimplementingparkingmaximums,reducingparkingminimums,oreliminatingparkingminimumsmaybeeffectivemeansofdecreasingmotorvehicletripsforwork,errands,andentertainment.ThisstudycanhelpadvisecityplannersanddevelopersinSanFranciscoandelsewhereastowhetherpoliciestoeliminateparkingminimumsandintroduceparkingmaximumswilleffectivelyrealizetheintendedgoalsofreducingcongestion,encouragingdenserdevelopment,makinghousingmoreaffordable,andsupportingimprovedurbanform. SanFranciscoisanideallaboratoryinwhichtostudytheinfluenceofresidentialoff‐streetparkingspaceavailabilityontravelbehavior.InseveraldenseSanFrancisconeighborhoodswithgoodtransitaccess,thecityrecentlyintroducedpoliciestoeliminateparkingrequirements.AlthoughplannersandanalystsbelieveSanFrancisco’sparkingpolicieswillinfluencetheeventualresidentsofunitswithoutoff‐streetparkingspacestobelessauto‐dependentthantheircounterpartswithoff‐streetparkingspaces,13thereislittleevidencetosuggestdifferencesinthetravelpreferencesofresidentsofthesetwotypesofneighborhood.14Infact,parkingpolicyisgenerallyalittle‐studiedtopic,andonethatistypicallyomittedfromtextbooks.15Althoughthosewhodostudyparkingpolicygenerallyagreethatminimumparkingrequirementsareunnecessary,thereisverylittleevidencetoactuallysuggestthatparkingpolicycanchangebehavior.16Residentialparkingistheareaofparkingpolicywiththeleastempiricalevidenceavailable,yetthisispossiblythemostimportantareaforstudybecauseofthevarietyofsocialandeconomiceffectsthatresidentialparkingpolicycanbringabout.17
12U.S.CensusBureau,“SanFrancisco,California:SelectedHousingCharacteristics:2005‐2007,”http://factfinder.census.gov(accessedAugust30,2009).13TomRadulovich,Interviewedbyauthorinperson,SanFrancisco,California,July2,2009andJoshuaSwitzky,Interviewedbyauthorinperson.SanFrancisco,California,July9,2009.14RoccoPendola,StephanieRuddy,andElmerTosta,“ResidentialParkingRequirementsinSanFrancisco:DoTheyAffectTravelBehavior?”UnpublishedreportpresentedtoLivableCitybySanFranciscoStateUniversityUrbanStudiesProgram,May2005.15JasonHenderson,“TheSpacesofParking:MappingthePoliticsofMobilityinSanFrancisco,”Antipode41,no.1(2009):73.16GregMarsden,“TheEvidenceBaseforParkingPolicies–AReview,”TransportPolicy,no.13(2006):455.17Ibid.
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AbouttheSurveyMethods ThedesiredrespondentgroupforthissurveywasSanFranciscoresidentswholiveinareasthathaveeliminatedparkingrequirements,andacontrolgroupofpeoplewholiveinpartsofthecitywhereresidentialparkingrequirementsarestillinplace.Assuch,allresidentsofSanFranciscooverage18werewithinthedesiredgroupofrespondentsforthissurvey.Asurveycontaining23questionscoveringtravel,parking,housing,anddemographicswasprepared,andwasadministeredtomorethan200peopleinSanFrancisco,bothonlinethroughneighborhoodassociationsandsocialnetworksandthroughinterceptsurveyadministrationatsupermarketsandinparks.Thisrandomsampleyielded182uniqueandusablesurveys.ThevariablesweredescribedwithdescriptivestatisticsandrelationshipsbetweenthevariablesweredescribedwithstatisticaltestsincludingChi‐SquareandT‐TestsofIndependentMeans.Afullanalysisofthesurveydatafollows.
DescriptionofReportOrganizationThereportofthisstudybeginswithanoverviewofcurrentparkingpolicypractice,
whichprovidesanin‐depthdiscussionofthedevelopmentandcurrentapplicationsofminimumandmaximumparkingrequirementsforalllanduses,withparticularfocusonresidentialparkingpolicies.Then,thediscussionnarrowstoabriefhistoryofparkingpolicyinSanFrancisco,andanoverviewofthecity’smorerecentintroductionofparkingmaximumsandretractionofparkingminimums.ThissectionincludesachartoutliningalloftheSanFrancisconeighborhoodswherethecityeliminatedparkingminimumsandadoptedparkingmaximumsforresidentialdevelopment.
Aliteraturereviewdetailstheeffectsofparkingrequirementsanddescribesthelimitedexistingresearchregardingthewaysinwhichresidentialparkingavailabilityshapestravelbehavior.Itthendiscussesthebodyofrelatedstudies,whichdescribetherelationshipsbetweenoff‐streetparkingrequirementsatdestinationsandtravelbehavior;landuseandtravelbehavior;parkingrequirementsandurbandesign;andparkingrequirementsandhousingaffordability.Theliteraturereviewfinisheswithdescriptionsofdevelopers’andthepublic’sperceptionsofparkingrequirements,andsuggestionsforalternativestoparkingrequirements.
Next,thereportdescribesthesurveyadministeredtoanswertheresearchquestions.Thissectionfocusesonthesurveyresultsandanalysisprocess,anddiscussesthesurveymethodology,includingthesurveyinstrument,sampleselection,surveyadministration,andlimitations.Finally,asetofrecommendationsandconclusionsdrawnfromthedataandresearchispresented.
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AnOverviewofCurrentParkingPolicyPractice
IntroductionAlthoughcitieshaverequireddeveloperstoprovideaminimumnumberofoff‐
streetparkingspacesforbothresidentialandcommercialusessinceshortlyaftertheadventofthemotorvehicle,inthe1980sinnovativeplannersstartedtointroduceanewwaveofparkingrequirementssuchascommercialparkingmaximumsandlimitsontheamountofparkingthatdevelopersarepermittedtobuildincertaindowntownareas.Today,citiesareconsideringimplementingawiderrangeofalternativeparkingstandards,suchaseliminationofparkingminimumsforbothresidentialandcommercialdevelopmentandresidentialparkingmaximums.Suchpoliciesaredesignedtolimittheinfluenceofthevehicleandtocreatewalkableandvibrantneighborhoodsandcommercialdestinationsbyreducingtheamountoflandtakenupbyparking.Thissectionwillexplorethehistoricaldevelopmentofparkingrequirementsandwillprovideanoverviewofthestateofthepracticeregardingcurrentparkingpolicy.
MinimumParkingRequirementsToday,freeparkingisavailablejustabouteverywheresuchasonthestreet,instrip
malls,oratthecondominiumcomplexesofourfriends.Thewidespreadavailabilityoffreeparkingdevelopedfromatraditionofprovidingcurbsidetethersforhorsesandcarriages.18Asmorepeopleboughtcarsandthedemandforcurbsideparkingincreased,citiesbegantoincludeinzoningordinancesrequirementsthatdevelopersprovidetheminimumnumberofoff‐streetparkingspacesnecessarytoaccommodatethedemandforparkingcreatedbydevelopmentonaparticularsite.Thispracticeisnowknownasaminimumparkingrequirement.By1946,asurveyof76citiesfoundthat17%hadimplementedminimumparkingrequirements.Afollow‐upstudyofthesame76citiesfiveyearslaterfoundthat71%ofcitieshadadoptedparkingrequirements,19makingfora54%jumpinthenumberofcitieswithminimumparkingrequirements.Today,mostcitiesestablishminimumoff‐streetparkingrequirementsinzoningordinancesforalllanduses,includingcommercial,office,andresidentialdevelopments.
BeyondthetraditionalcustomofprovidingfreeparkingintheUnitedStates,thereareseveralreasonswhycitiestodayrequiredeveloperstoprovideoff‐streetparkingspaces.Twoprimarymotivationsarecommercialviabilityandmarketdemand.Developersandcitieswanttomaximizethemarketdemandforaparticulartypeofhousingorbusiness,andthustheconventionalbeliefisthatalanduseshouldprovideoff‐streetparkinginaquantitythatissufficienttoaccommodateallofthevehiclesthatmightwanttoaccessthatparticularlanduse.20Neitherdevelopersnorfunderswanttodiscouragepeoplefrompurchasing,renting,orshoppingatapropertybecauseitisinaccessible.Also,city
18DonaldShoup,TheHighCostofFreeParking(Chicago:PlannersPress,2004),1.19Mogren,EdwardandWilburSmith,ZoningandTraffic(Saugatuck,Connecticut:EnoFoundationforHighwayTrafficControl,1952)asquotedinDonaldShoup,TheHighCostofFreeParking(Chicago:PlannersPress,2004),22.20RichardWillson,“SuburbanParkingRequirements:ATacitPolicyforAutomobileUseandSprawl,”JournaloftheAmericanPlanningAssociation61,no.1(1995):30.
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governmentsliketominimizethenumberofvehiclesthat“spillover”intoon‐streetparkingspacesinneighboringresidentialareasorillegalspaces.21
Citiestypicallyestablishminimumparkingrequirementsinoneoftwoways:byfollowingexamplessetbyneighboringcitiesorbyusingamanualdevelopedbytheInstituteofTransportationEngineers,calledParkingGeneration.However,accordingtoparkingpolicyresearcherDonaldShoup,bothofthesemethodsareflawed.Bycopyingtheparkingplansenactedbyotherlocalagencies,citiesruntheriskofrepeatingthemistakesofothers,andmayinadvertentlyreplicatearbitrarycalculations.22TheparkingratesoutlinedinParkingGenerationarenotgenerallyapplicable,astheyarebasedonafewparkingsurveysthatareconductedduringpeakhoursinsuburbanlocations.23Althoughmostcitieslackthefinancialresourcestoconductindividualparkingdemandsurveysforeachlanduse,itisdifficulttorationalizeapplyingtheITEratestoallcircumstances.
Sincemostcitiesfollowthesamerulesofthumbtocalculateparkingrequirements,manycitiesimplementrequirementsthataresimilar.TypicalminimumparkingratesinCaliforniacitiesareasfollows:24
o Residential:onetotwospacesperunit.(1:1or2:1)o OfficeSpace:threespacesper1,000squarefeetofofficespace.o Retail:onetofourspacesper1,000squarefeetofretailspace.o Restaurant:variesgreatlybyrestauranttypeandjurisdiction;butonespace
per200squarefeetisfairlytypical.Manydeveloperschoosetobuildmoreparkingthantheminimumamountrequiredbecausefundersfavorprojectswithabundantparking.
Althoughdriversdonotpayadirectfeetousemostparkingspaces,thespacesarenotfree:developersmustpaytobuildthespacesandtheyaddthefeetorentalandpurchaseprices.Commercialtenants,inturn,passthefeeontoconsumersbyaddingittothepricesforgoodsandservices.Theperceptionthatparkingisfreeandplentifulandtherealitythatfreeparkingisnearlyalwaysavailablemakesdrivingtoadestinationseemmorecosteffectivethantakingtransit,whichentailspaymentofafareforeachride.Studieshavefoundthatminimumparkingrequirementscanlowerdensity,encouragesprawl,increasecongestion,andreducedemandfortransitservices.25Thesefactors,incombination,createauto‐centeredcommunitiesanddowntownareaswithlittlestreetscapevitality.
Plannersarebeginningtorecognizetheinfluenceofplentifulparkingoncommunityvitalityandarestartingtoscrutinizethepracticeofminimumparkingrequirements.Asaresult,somecommunities,suchasBerkeley,California,allowexceptionstoparkingminimumsfordeveloperswhoopttobuildfewerthantherequirednumberofspaces.26Othercities,suchasSeattle,Washington,haveeliminatedminimumparkingrequirements
21Ibid.22DonaldShoup,“TheTroublewithMinimumParkingRequirements,”TransportationResearchPartA:PolicyandPractice,no.33(1999):550.23Ibid.,551.24MetropolitanTransportationCommission,“DevelopingParkingPoliciestoSupportSmartGrowthinLocalJurisdictions:BestPractices,”(MetropolitanTransportationCommission,Report,May2007),24‐25.25RichardWillson,“SuburbanParkingRequirements:ATacitPolicyforAutomobileUseandSprawl,”JournaloftheAmericanPlanningAssociation61,no.1(1995):38‐40.26AdamMillard‐Ball,“PuttingonTheirParkingCaps,”Planning,April2002.
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altogetherincertainareas.InSeattle,developersarenotrequiredtoprovideaminimumnumberofparkingspacesforvehiclesinthedowntowncore,thoughtheyarerequiredtoprovideparkingspacesforbicycles.27ParkingisalsonotrequiredincommercialzonesnearlightrailstationsinSeattle.28Meanwhile,Portland,Oregonhaseliminatedminimumparkingrequirementsinthecentralresidentialandcommercialcore,neighborhoodcommercialzones,andcertainotherareaszonedforcommercialandofficelanduses.29Portlandalsoexcludes“siteslocatedlessthan500feetfromatransitstreetwith20‐minutepeakhourservice”fromminimumparkingrequirements30andallowsdeveloperstoprovidebicycleparkinginplaceof25%ofrequiredparking.31Asthediscussionbelowwillexploreinmoredetail,SanFranciscohasalsoeliminatedoff‐streetparkingminimumsaltogetherincertainpartsofthecityinandarounddowntown.
Thecitiesdiscussedinthissectionhaveadoptedprogressiveparkingpoliciesthatserveasalternativestominimumoff‐streetparkingrequirements.Inthenextsection,Iwilldiscussanothergroupofinnovativeparkingpoliciesfromcitiesthathavedecidedtochangethestatusquoofparkingpolicybyestablishingthresholdslimitingtheamountofparkingthatdevelopersmaybuildincertainareas.
MaximumParkingRequirements Plannerslookingtopreventsprawlandauto‐dependencyinfavorofcreatingmorewalkableandvibrantplacesaremorefrequentlyconsideringparkingmaximumsinplaceoftraditionalparkingminimums.Asopposedtoparkingminimums,whichrequiredeveloperstoprovideacertainminimumnumberofparkingspaces,whichtheycanexceed,maximumparkingrequirementsestablishalimitontheamountofparkingspacesthatadevelopercanprovide.Citiesmayestablishparkingmaximumsinsteadofparkingminimums,orinconcertwithaparkingminimum.Likeparkingminimums,maximumparkingdesignationsareincludedinzoningordinancesorneighborhoodplans. Parkingmaximumsarearelativelynewalternativeparkingpolicystrategy.Thelimitonthenumberofspacesallowedistypicallydeterminedinoneoftwoways.Somecitiesbaseparkingmaximumsontheavailabilityofalternativemodesoftransportation(asinPortland,Oregon;SanFrancisco,California;andCambridge,Massachusetts,whichalltieparkingmaximumstotransitpolicies).32Othercitiesconductparkingutilizationstudieslocallytoderiveparkingmaximumallowancesfortheirmunicipality,ratherthanrelyingonParkingGenerationrates.ThecitiesthathaveconductedutilizationstudiesincludePortland,Bend,andHoodRiverinOregon.33
Cambridge,Massachusettsiscreditedwithbeingoneofthefirstcitiestosetparkingmaximums,whichitdidinthe1980s.Cambridge’sparkingmaximumtodayallows,for
27CityofSeattleMunicipalCode,Title23,SubtitleIII,Subdivision2,Chapter23.49,SubchapterI.“DowntownZoning:GeneralProvisions.”28CityofSeattleMunicipalCode,Title23,SubtitleIII,Subdivision2,Chapter23.54.“QuantityandDesignStandardsforAccessandOff‐StreetParking.”29CityofPortlandCityCode,Chapter33.266.110:ParkingandLoading,MinimumRequiredParkingSpaces.30Ibid.31Ibid.32MetropolitanTransportationCommission,“DevelopingParkingPoliciestoSupportSmartGrowthinLocalJurisdictions:BestPractices,”(MetropolitanTransportationCommission,Report,May2007),35.33Ibid.
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example,foramaximumoftwoparkingspacesper800squarefeetofgeneralofficespace,orfortwospacesperfiveseatsatabar.34Inadditiontoremovingparkingminimums,Portlandhasalsosetparkingmaximumsinpartsofthedowntownbusinessdistrict.Themaximumallows,forexample,.7off‐streetparkingspacesper1,000squarefeetofofficespace,and1.35spacesperresidentialunit.35SanFranciscohasalsosetparkingmaximumsinseveralneighborhoods.AdetaileddiscussionofSanFrancisco’sparkingpoliciesandrequirementswillfollow.
Althoughrealizedbenefitsofresidentialparkingmaximumsarenotwell‐documented,thereissomeevidencethatparkingmaximumsleadtomarginalincreasesintransitridershipanddecreasesinvehiclecongestion.36Citiesmaychoosetoimposeparkingmaximumstoencouragetransitridership,maximizelimitedlandresources,andimproveurbanaesthetics.37Unitswithoutparkingspacesaremoreaffordable,38soremovingthecostofaparkingspacefromthepriceofahouse(alsoknownas“unbundling”parking)canmakehousingaffordableformorepeople. Despitethebenefits,parkingmaximumsasanalternativeparkingpolicyareoftencontroversial.Developersareoftenopposedtoparkingmaximumsbecause,overthemanyyearsthatminimumparkingrequirementshavebeenthestatusquoindevelopment,developershavecreatedaruleofthumbforwhatwillsell:residentialunitssuchassinglefamilyhomes,condominiums,orapartmentswitharatioofatleastoneparkingspaceperunit(1:1).39Itisoftendifficultfordeveloperstoconvincefunderstoinvestinprojectsthatprovidelessthanoneparkingspaceperunitbecauseitisadeeplyrootedindustrystandard.Developersalsofearthatunitswithoutparkingwillnotbeabletocompetewithsimilardevelopments.40
However,twostudieshaveproducedevidencecontradictingdevelopers’andfunders’fearsaboutthemarketabilityofunitswithoutparking.AstudyoftheeffectsofparkingrequirementsonthecostofhomesinSanFranciscofoundthatcondominiumssoldwithaparkingspaceactuallyhaveaslowerabsorptionratethanthosewithoutaparkingspace.Thatstudyfoundthatcondominiumunitswithparkingtook41dayslongertosellthanthosewithout.41Anotherstudyfoundthathousingwithoutparkingprovidesdeveloperswithahigherrateofreturn.Theauthorofthatstudycalculatedthatparking
34CityofCambridgeZoningOrdinance,Section6.36:ScheduleofParkingandLoadingRequirements.35MetropolitanTransportationCommission,“DevelopingParkingPoliciestoSupportSmartGrowthinLocalJurisdictions:BestPractices,”(MetropolitanTransportationCommission,Report,May2007),36‐37.36SanFranciscoPlanningandUrbanResearchAssociation,“ParkingandLivabilityinDowntownSanFrancisco:PoliciestoReduceCongestion.”www.spur.org/publications/library/report/parkingandlivabilityindowntownsf_010105(accessedSeptember27,2009)37JoshuaSwitzky,Interviewedbyauthorinperson.SanFrancisco,California,July9,2009.38JiaandWachs,158.39LukeH.Klipp,“TheRealCostsofSanFrancisco’sOff‐StreetResidentialParkingRequirements:AnAnalysisofParking’sImpactonHousingFinanceAbilityandAffordability,”Master’sThesis,UniversityofCalifornia,Berkeley,2004,6.40RichardWillson,“ParkingPolicyforTransit‐OrientedDevelopment:LessonsforCities,TransitAgencies,andDevelopers.”JournalofPublicTransportation8,no.5(2005):87.41WenyuJiaandMartinWachs,“ParkingRequirementsandHousingAffordability:CaseStudyofSanFrancisco,”TransportationResearchRecord,no.1685(1999):159.
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sellsforlessthanitcoststobuild,andthataunitwithoutparkingyieldsasignificantlygreaterprofitpersquarefootthanaunitwithparking.42 IwillnowturntoadiscussionofthedevelopmentofparkingpolicyintheCityofSanFrancisco,fromtheintroductionofparkingminimumstothecurrentriseofparkingmaximums.
42Klipp,26.
AHistoryofParkingPolicyinSanFrancisco
1906‐1955:SanFranciscoBeforeMinimumParkingRequirementsMuchoftoday’sSanFranciscowasbuiltintheaftermathofthe1906earthquake,
duringtheyearswhenmotorvehicleusewasinitiallygrowing.NorthBeachandChinatownaretwodense,mixedcommercialandresidentialdistrictsnearDowntownSanFranciscothatwererebuiltimmediatelyfollowingtheearthquake.Thebuildingsaresetattheedgeofthesidewalkwithretailonthegroundfloorandhousingabove.BuildingsinNorthBeachandChinatowndonothavegarages,driveways,orparkinglots.Today,findingstreetparkingtherecanbecompetitive,butitdoesnotkeeppeoplefromvisiting,shopping,ordining,asevidencedbythecrowdsfoundeatingoutsideorbrowsingshopwindowsonweekendnights.
AlthoughSanFrancisco’sdowntowncoreremaineddense,likemanyothercitiesthatdevelopedduringtheearly20thCentury,SanFranciscobegantodevelopinanauto‐centricpatternasvehiclesbecameubiquitousduringthe1920sand1930s.Duringthoseyears,developersconstructedmanybuildingswithground‐floorparkinggaragesandresidentialunitsontop,althoughtheywerenotyetrequiredtoprovideparking.Manyofthecity’souterneighborhoods,suchastheSunsetDistrictandtheRichmondDistrict,developedduringthisperiod.Single‐familyhomeswithgarages,neighborhoodcommercialdistricts,andsupermarketswithlargeparkinglotsdefinetheseneighborhoodstoday.
1955‐1997:TheEraofParkingMinimumsIn1955,SanFranciscoinstituteditsfirstminimumparkingrequirementofone
residentialoff‐streetparkingspaceforeachdwellingunit.Thisrequirementremainsineffectinmostneighborhoodsinthecitytoday.In1960,thecityaddedcommercialandindustrialparkingrequirementstothezoningcode.43In1968,thecityadoptedwhatisknownasa“softmaximum”whereindeveloperscanprovidenomorethan150%oftheminimumnumberofrequiredparkingspacesasaccessory.44However,thereareprovisionswherebythecitygrantsconditionalusepermitstodeveloperswhowishtoprovidemoreparking.
In1973,shortlyafterBayAreaRapidTransit(BART)commuterrailservicestartedtooperate,SanFranciscointroducedits“TransitFirst”policy,whichcontinuestocomprisethetheoreticalfoundationofthecity’sGeneralPlan.45Thepolicyprioritizesinvestmentintransitandencouragesstreetdesignandparkingpoliciesthatminimizevehicletraffic.ThepolicyguidesthepathofdevelopmentinSanFranciscobyencouraginginvestmentsininfrastructurethatbenefitshighly‐connected,multi‐modaltransportationsystemsthatadequatelyaccommodatepedestrians,bicyclists,andtransitridersaswellasdriversofmotorvehicles.46
43LivableCity,“ABriefHistoryofParkingRequirementsinSanFrancisco,”http://www.livablecity.org/campaigns/parkinghistory.html(accessedDecember7,2009).44Ibid.45CityofSanFranciscoGeneralPlan,TransportationElement:TheFreewayRevoltand"TransitFirst"(1960‐1989).46Ibid.
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Thecitydoesnotrequireconstructionofoff‐streetparkingfacilitiesinconjunctionwiththedevelopmentofcommercialbuildingsdowntown,anditmaintainsacommercialparkingmaximumthatallowsdeveloperstoconstructparkingforupto7%ofthegrossfloorareaofadevelopment.47Thistotalsaboutoneparkingspaceper4,000squarefeetofdevelopedspace.DevelopersmayexceedthatlimitwithaconditionalusepermitfromthePlanningCommission,whichisonlygrantedifthereisadeterminationthattripstheparkingwouldservecannotbeaccommodatedbytransit,carpooling,oruseofexistingparking,andiftheparkingwillnotcontributetocongestionordisrupttransit.48Inmorerecentyears,thecityhasbeguntoextendparkingmaximumstoresidentialdevelopmentdowntownandinareasthatarewell‐servedbytransit.
1997andBeyond:DiscardingResidentialParkingMinimumsandIntroducingMaximums
Today,thecity’spopulationdensityis17,259peoplepersquaremile,49makingitoneofthedensestcitiesinthecountry.SanFrancisco’sdensityisgreaterthanthatofChicago,Boston,orPhiladelphia,threecitieswithextensiveandwell‐utilizedtransitsystems.However,manySanFranciscoresidentsownvehiclesandusethem.In2008,thepopulationofSanFranciscowas798,17650andtherewere470,333vehiclesregisteredinthecity.51Ifadifferentindividualownedeachoneofthosevehicles,thiswouldmeanthat59.8%ofSanFranciscoresidentsowntheirownvehicle.Additionally,39.2%ofthecity’spopulationreportscommutingtoworkbycarortruck.52
Although,initially,themajorityofregionalofficejobswerelocatedinSanFrancisco’sdowntowncore,theBayArearegionisexperiencingasprawlinggrowthintechnology‐relatedjobsinSiliconValley,whichislocatedapproximately40milessouthofSanFrancisco.MostoftheofficespaceinSiliconValleyislocatedinlow‐risecar‐orientedbusinessparks,andmanyofthepeoplewhoworkintheseofficescommutefromSanFranciscodistrictssuchasthetrendySouthofMarket,Mission,andNoeValleyneighborhoods.
In1997,SanFranciscointroduceditsfirstparkingmaximuminMissionBayandithasimplementedseveraladditionalneighborhood‐basedparkingmaximumssincethen.Table1containsachartdescribingthecity’sresidentialparkingmaximums.Inadditionto
47CityandCountyofSanFranciscoPublicWorksandPlanningDepartments,“ParkinginSanFrancisco:ConditionsandTrends,”December1975.48SanFranciscoPlanningandUrbanResearchAssociation,“BallotAnalysis,November2007,PropositionH:ParkingInitiative,”http://spur.org/goodgovernment/ballotanalysis/Nov2007/proph(accessedDecember7,2009).49UnitedStatesCensusBureau,“PersonsperSquareMile:2008,”http://factfinder.census.gov/(accessedDecember7,2009).50UnitedStatesCensusBureau,“FactSheet:SanFranciscoCity:2006‐2008AmericanCommunitySurvey3‐YearEstimates,”http://factfinder.census.gov/(accessedDecember7,2009).51StateofCaliforniaDepartmentofMotorVehicles,“EstimatedVehiclesRegisteredbyCountyForthePeriodofJanuary1ThroughDecember31,2008,”http://www.dmv.ca.gov/about/profile/est_fees_pd_by_county.pdf(accessedDecember7,2009).52UnitedStatesCensusBureau,“FactSheet:SanFranciscoCity:2006‐2008AmericanCommunitySurvey3‐YearEstimates,”http://factfinder.census.gov/(accessedDecember7,2009).
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implementingparkingmaximums,thecityhasalsoeliminatedparkingminimumsintheneighborhoodswithparkingmaximums.
ThepropagationofparkingmaximumsincludedinNeighborhoodPlansinSanFranciscoindicatesthatthecityisdedicatedtoreachingthegoalssetforthinitsTransit‐Firstpolicy.Accordingtothecity’sPlanningDepartment,residentialparkingmaximumsaregoodforthecityforseveralreasons.First,theydecreasetheoverallnumberofcarsinthecityandencouragepeoplewholiveneartransittouseit.53Italsomaximizestheefficiencyoflimitedlandinadensearea.54Finally,fromanurbandesignpointofview,buildingfewerparkingentranceswillcreatemoreattractiveandwalkableplaces.55
Table 1. Maximum Parking Allowances in San Francisco
Sources:CityandCountyofSanFranciscoMunicipalCode,Section151.1:ScheduleofPermittedOff‐StreetParkingSpacesinSpecifiedDistricts;CityandCountyofSanFranciscoPlanningDepartment.MarketandOctaviaAreaPlan.May30,2008;CityandCountyofSanFranciscoRedevelopmentAgency.DesignforDevelopmentfortheMissionBayNorthandSouthProjectAreas.ApprovedMarch16,2004;CityandCountyofSanFranciscoPlanningDepartment.EasternNeighborhoodsZoningGuide.January19,2009.
53JoshuaSwitzky,Interviewedbyauthorinperson.SanFrancisco,California,July9,2009.54Ibid.55Ibid.
Year Neighborhood DescriptionParkingMaximum ExceptionsAllowed?
1998 MissionBay RedevelopmentArea1spaceperunit Nonespecified
2005RinconHill(RHDTR)
High‐RiseResidential,adjacenttodowntown
.5spacesperunit
Upto1parkingspaceperunitthroughPlanningCommissionreviewifspacesareoperatedwithmechanicalstackersorvalet.Requiresunbundlingofparking
2006 Downtown(C‐3)DenseCommercial/Office/High‐RiseResidential
.75spaceperunit
Allowsmaximumof1parkingspaceperunitforunitswith2ormorebedrooms
2008
EasternNeighborhoods:‐Mission‐EastSOMA‐CentralWaterfront‐ShowcaseSquare/Potrero
Residential,Eastofdowntown
.5to.75spacesperunit
Upto.75‐1parkingspaceperunitthroughPlanningCommissionreviewifspacesareoperatedwithmechanicalstackersorvalet.
2008 MarketandOctaviaResidential/Commercial,adjacenttodowntown
.75spaceperunit
Allowsmaximumof1parkingspaceperunitforunitswith2ormorebedrooms
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InDowntownSanFrancisco,theminimumoff‐streetresidentialparkingrequirementwasonespaceforeveryfourunits(1:4)foraslongasanyonecouldrememberuntilthecityimplementedaparkingmaximumintheC‐3ZoningDistrictin2006.56However,developerswouldoftenbuildmoreorlessparkingthanrequiredwithapprovalfromthecity.57So,althoughthecurrentweakeconomyhaspreventeddevelopersfromconstructingmanynewbuildingssincetheparkingmaximumswereestablished,thereisaprecedentinthecityforconstructingbuildingswithlimitedoff‐streetparkingspaces.WiththeimplementationoftheparkingmaximumsindowntownSanFrancisco,thereisnolongeranyprovisionforexceedingtheamountofparkingspecifiedasallowableexceptionsinTable1.
56Ibid.57Ibid.
LiteratureReview
Introduction Thereiscurrentlyadebateswirlingaroundtheissueofminimumparkingrequirementsforresidentialdevelopments.Whileithasbeencommonpracticeforcitiestorequiredeveloperstoprovideaminimumamountofparkingformorethan70years,recentlyresearchershavebeguntodiscusstheeffectsofsuchpracticesonurbanformandtravelbehavior.Thisliteraturereviewpointsoutsomeofthekeyargumentsagainstthecontinueduseofminimumparkingrequirementsasthestatusquoinresidentialdevelopmentanddiscussesthewidearrayofsolutionsthathavebeenproposedasalternativestominimumparkingrequirements. Thispaperisspecificallyinterestedintheinfluenceoftheavailabilityofaresidentialoff‐streetparkingspaceonindividuals’travelbehavior.Despitethemanyargumentsagainstminimumparkingrequirements,therehasbeenvirtuallynoresearchconductedtospecificallydescribemyresearchquestion.Severalresearchershavenotedthatthistopicisonethatwarrantsfurtherinvestigation.58Thereare,however,manystudiesthatexaminecloselyrelatedtopicsthathavedirectinfluenceontravelbehavior. Inthisliteraturereview,Iwillstartwithadiscussionofthewidelyrecordednegativeeffectsofminimumparkingrequirements.Iwillthenturntoadiscussionofthefewstudiesthatdirectlyaddresshowavailabilityofanoff‐streetparkingspaceinfluencestravelbehavior.Next,Iwillprovideanoverviewoftherelatedstudiesthatdiscusshowtheavailabilityofparkingatadestinationmayinfluencetravelbehavior,andamoregeneraldiscussionofhowurbanformandlanduseinfluencetravelbehavior.Iwillthendiscussthehandfulofstudiesthatconsidertheimpactsofparkingrequirementsonurbandesignbeforeturningtoadiscussionofhowparkingrequirementsinfluencehousingprices,whichisthedominantfocusofresearchintotheimpactsofparkingrequirements.Beforeturningtopolicyconsiderations,Iwillprovideananalysisofthestudiesthatdescribedevelopers’andresidents’perceptionsofresidentialparking.Finally,IwilldiscussthevarietyofalternativestominimumparkingrequirementsthathavebeenproposedrecentlyandIwillidentifygapsintheliterature.
MainThemesandDebates
Thenegativeeffectsofminimumparkingrequirements
Traditionally,mostcitieshavefollowedasystemofminimumparkingrequirementstoensurethatnewdevelopmentprovidesenoughparkingtoaccommodatealluses,withoutcreatingspilloverparkingandexcessthroughtrafficonresidentialstreets.Theserequirementsaimtohelpfosterefficienttransportationsystems,strongeconomies,
58LukeH.Klipp,“TheRealCostsofSanFrancisco’sOff‐StreetResidentialParkingRequirements:AnAnalysisofParking’sImpactonHousingFinanceAbilityandAffordability,”Master’sThesis,UniversityofCalifornia,Berkeley,2004:17;GregMarsden,“TheEvidenceBaseforParkingPolicies–AReview,”TransportPolicy,no.13(2006):455;JohnNobleandMikeJenks,Parking:DemandandProvisioninPrivateSectorHousingDevelopments,Eynsham,England:InformationPress,1996:11.
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accessibility,cleanurbanenvironments,andsafety.59Essentially,mostcitiesdeterminethedemandforparkingthatvariouslanduseswillcreateatpeaktimesandwritearequiredminimumnumberofparkingspacesforeachuseintotheirzoningcodes.Todeterminethenecessaryquantityofparking,theytypicallyconsulttheInstituteofTransportationEngineersParkingGenerationmanualorsurveyneighboringcities.60
Today,nearlyeveryresearcherstudyingparkingpolicyhaspointedoutfaultwiththissystem.Althoughmostresearchersstudyingthetopicwouldagreethatparkingrequirementsshouldbecalculateddifferently,theyhavemanydifferentargumentstosupporttheircontentionsthatchangesareneeded.Themainargumentsthatresearchersciteagainstminimumparkingrequirementsareasfollows:
o ITEParkingGenerationmethodologyisflawed61o Requiredparkingraisesthepriceofgoodsandhousing62o Requiredparkingsubsidizesthecostofoperatingavehicle63o Requiredparkingleadstoincreaseduseofmotorvehicles64o Requiredparkingmakestransitlessviable65o Requiredparkingreducestheamountoflandavailablefordevelopment66o Requiredparkingleadstoincreasedsprawl67o Requiredparkingharmstheenvironment68o Requiredparkingleadstounpleasanturbandesign69
Inthesubsequentpages,Iwillprovideanoverviewofthebodyofliteraturethathasemergedtodescribetheeffectsofparkingrequirementsandthealternativepoliciesthathavebeenproposedtoaddresstheseissues.
59Marsden,448.60Ryan.Russo,“Parking&Housing:BestPracticesforIncreasingHousingAffordabilityandAchievingSmartGrowth,”Master’sThesis,UniversityofCalifornia,Berkeley,2001:12.61ChristopherCherry,ElizabethDeakin,NathanHiggins,andS.BrianHuey,“Systems‐LevelApproachtoSustainableUrbanArterialRevitalization,”TransportationResearchRecord,no.1977(2006):208;DonaldShoup,“TheHighCostofFreeParking,”JournalofPlanningEducationandResearch,no.17(1997):4;DonaldShoup,“TheTroublewithMinimumParkingRequirements,”TransportationResearchPartA:PolicyandPractice,no.33(1999):551.62JasonHenderson,“TheSpacesofParking:MappingthePoliticsofMobilityinSanFrancisco,”Antipode41,no.1(2009):77;ToddLitman,“ParkingRequirementImpactsonHousingAffordability,”VictoriaTransportPolicyInstitute(January2009):11;Russo,11;Shoup(1999),556;DonaldShoup,TheHighCostofFreeParking,Chicago:AmericanPlanningAssociationPress,2005:141‐143.63Shoup(1997),11‐12;DonaldShoup,TheHighCostofFreeParking,Chicago:AmericanPlanningAssociationPress,2005:217;RachelWeinberger,MarkSeamanandCarolynJohnson,“ResidentialOff‐StreetParking:CarOwnership,VehicleMilesTraveled,andRelatedCarbonEmissions(NewYorkCityCaseStudy),”TransportationResearchRecord,no.2118(2009):25.64Litman(January2009),11;Russo,1,11;Weinberger,Seaman,andJohnson,25;RichardWillson,“SuburbanParkingRequirements:ATacitPolicyforAutomobileUseandSprawl,”JournaloftheAmericanPlanningAssociation61,no.1(1995):34.65Henderson,77;Russo,10.66Litman(January2009),9‐10;Russo,1;Shoup(1997),11.67Litman(January2009),10‐11;NobleandJenks,5‐6;Russo,1,10;Willson(1995),36‐37.68Henderson,77;NobleandJenks,5‐6;Russo,11;Shoup(2005),291;Willson(1995),34.69Litman(January2009),11;NobleandJenks,5‐6;Shoup(2005),129‐135.
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Howavailabilityofanoff‐streetresidentialparkingspaceinfluencestravelbehavior
Thefewarticlesthatspecificallydiscusshowresidentialparkingavailabilityinfluencesmodechoicesuggestthatpeoplewithoutanavailableresidentialoff‐streetparkingspacetendtodrivelessthanthosewhohaveaccesstoaparkingspaceathome.However,onlyahandfulofpriorstudieshavespecificallystudiedthisquestion.
AstudyconductedinNewYorkcomparedthetravelbehaviorofresidentsoftwoneighborhoodsthatareequallyservedbytransitandaboutthesamedistancefromManhattan’scentralbusinessdistrict:JacksonHeights,QueensandParkSlope,Brooklyn.70Usingcityparkinglotdata,taxrecords,andvisualrecording,theresearchersfoundthatresidentsofJacksonHeights,whichhas156%moreparkingthanParkSlope71,were45%morelikelytodrivetoworkinManhattanthanresidentsofParkSlope.72Althoughtheresultssuggestthatpeoplewilldrivemorewhenaresidentialparkingspaceisavailable,theauthorsmentionadditionalfactorsthatcouldaccountforthehigherrateofManhattan‐boundautotripsoriginatinginJacksonHeights,suchashigherratesofshiftworkormoreparkingattheworkplacesofJacksonHeightsresidents.73
Agroupresearchingwhetheravailabilityofaresidentialoff‐streetparkingspaceinSanFranciscoinfluencestravelbehaviorfoundconflictingresultsastowhetherthetravelbehaviorofpeoplewithparkingvariesfromthosewithout.74Theauthorsfirstadministeredasurveywithasamplesizeof42andfoundthatindevelopmentswithparkingratiosofoneparkingspaceperunit(1:1),81.5%ofresidentsownedacar,50%drovetowork,and70.4%drovefornon‐workpurposes.75Indevelopmentswithparkingratiosoflessthan1:1,theyfoundthat46.7%ownedacar,26.7%drovetowork,and42.9%drovefornon‐workpurposes.76TheyalsoconductedasmallTripGenerationstudy,inwhichtheyfoundthatadevelopmentinaneighborhoodwithagoodtransitsystemandaparkingratioof.14:1hadthehighestTripGenerationrate(1.67autotripsperparkingspaceduringpeakhours),althoughtheotherbuildingsexaminedhadhightripgenerationratesaswell(.79,.42,and.55).77Theresults,whichareinconclusive,focusedonahandfulofspecificdevelopments,anduseaverysmallsamplesize,suggestthatpeoplewithoutparkingathomedrivelessthanthosewithaparkingspace,butthosewhohaveaparkingspacedrivefrequently. Finally,areviewof26residentialtransitorienteddevelopments(TODs)acrossCaliforniafoundthatresidentsofdevelopmentswithmoreparkingusedtransitlessforworktrips,butthisfindingwasnotstatisticallysignificant.78ThestudyalsofoundthatTODswithhigherratesoftransitusehadaboutthesameamountofparkingspace,
70Weinberger,Seaman,andJohnson,27.71Ibid.72Ibid.,26.73Ibid.,26.74RoccoPendola,StephanieRuddy,andElmerTosta,“ResidentialParkingRequirementsinSanFrancisco:DoTheyAffectTravelBehavior?”UnpublishedreportpresentedtoLivableCitybySanFranciscoStateUniversityUrbanStudiesProgram,May2005:16‐17.75Ibid.76Ibid.77Ibid.,18.78RichardWillson,“ParkingPolicyforTransit‐OrientedDevelopment:LessonsforCities,TransitAgencies,andDevelopers.”JournalofPublicTransportation8,no.5(2005):81.
18
suggestingthattoomuchparkingwasprovidedconsideringthetransit‐accessibilityofthedevelopment.79
Howavailabilityofaparkingspaceatthedestinationinfluencestravelbehavior
Sincetherearenotmanystudiesthatexaminetheinfluenceofresidentialparkingavailabilityonpeoples’travelbehavior,itisinstructivetolookatthebodyofliteraturethatlooksatwhetherparkingavailabilityatworkorshoppinglocationsinfluencestravelbehavior.Theliteratureonthistopicsuggeststhatpeopledrivemorewhenthereisaparkingspaceavailableatthedestination.
Onestudyof10officeparksinSouthernCaliforniathatmetminimumparkingrequirementsfoundthatpeakutilizationwasonly56%,80whichsuggeststhattheparkingminimumsaretoohigh.Thisstudyalsorevealedthatpeoplewhoworkatofficeswithfreeparkingtravelwith10%fewerpeoplethanthosewhoworkatofficeswithoutfreeparking,becauselesspeopleareridingtransitorcarpooling.81InCuritiba,Brazil,acitythatiswellknownintransportationplanningcirclesforitsextensiveBusRapidTransit(BRT)system,parkingminimumswereimposedevenlyinthedowntownandoutskirtareas.ArecentstudyoftheareasaroundfiveBRTstationsinCuritibafoundthatparkingminimumsledtofreeorcheapparkinginthecity,promotingsingleoccupantvehicleuseandrunningagainstthestatedgoalsofthecity’sadoptedlandusepolicies.82
Meanwhile,asmall,informalstudyofthreeworksitesinScotland(ahospital,acorporateheadquarters,andabusinesspark)builtincompliancewithGreatBritain’sparkingmaximumrecommendationfoundthatratesoftransituse,walking,andbicyclingwere14%to20%higheratthesiteswithlimitedparkingthanthatexpectedatlocationswithsimilarlanduses.83Moreresearchiscertainlynecessarytoconfirmtheresultsofthisunpublished,limitedstudy.
Howlanduseinfluencestravelbehavior
Anotherusefulgroupofstudieslooksathowlanduseinfluencestravelbehavior.Avarietyoflandusefactorsotherthanparkingcaninfluencetravelbehavior,includingresidentialdensity,landusemix,employmentdensity,roadwaydesign,bicyclefacilities,sitedesign,andretail.84Travelbehaviorindicatorsthatcanbestudiedincludemodechoice,vehiclemilestraveledandvehicleownership.Somestudiesinthiscategoryfindthatdensitycaninfluencemodechoice,andinrecentyearsthisprovesparticularlytrueforresidentsofTODs.However,anotherbodyofliteratureinthisareahasreachedinconclusiveresults,andsomearguethatit’simpossibletoisolatethefactorsthatinfluencetravelbehavior.
79Ibid.,8280Willson(1995),32.81Willson(1995),36.82ChristopherZiemann,“IsCuritiba,BraziltheModelCityforParkingManagement?”Submittedforpresentationandpublication,88thAnnualMeetingoftheTransportationResearchBoard,Washington,DC,2009:14.83TomRyeandStephenIson,“TheUseandImpactofMaximumParkingStandardsinScotland,UK,”Submittedforpresentationandpublication,86thAnnualMeetingoftheTransportationResearchBoard,Washington,DC,2007:12‐13.84ToddLitman,“LandUseImpactsonTransport,”VictoriaTransportPolicyInstitute(August2009):2.
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Alandmarkstudyconductedin1995foundthatresidentialdensityandmixedusesgenerallyinfluencepeopletousesingleoccupantvehicleslessfrequentlyandtousetransitorwalkmore.85Inprofessionalpractice,itiscommonlyacceptedthatpeoplewillusecarslessoftenwhenthereareothermeansoftravelsuchastransitavailable,walkabledestinationsnearby,andlocalemploymentopportunities.86Similarly,studiesofTODs,whicharesimilartomostdenseurbanareasintheirproximitytotransitandmixedlanduses,haverevealedthatTODresidentstypicallyownfewercarsduetosmallerhouseholdsizeandproximitytotransit87andusetransittwotofivetimesmoreoften.88Therecouldbeaself‐selectionfactoratplaywhenitcomestoTODresidents,which,asotherstudiespointout,mustalwaysbetakenintoconsiderationwhenlinkinglandusetotravelbehavior.89
A1998studydidnotfindthatanyofthelandusesanalyzedinfluencedtravelbehaviorwithgreatstatisticalsignificance,andconcludedthatwecannotsufficientlyuselandusetopredictpeoples’travelbehavior.90Usingaregressionmodelthataccountedforpeoples’housinglocationpreferences,thisstudyfoundaweakcorrelationthatsuggestsresidentsofzipcodeswithhigherserviceemploymentdensitymadeagreaternumberofnon‐worktripsinsingleoccupantvehicles,andthosewholivedinzipcodeswithhigherretailemploymentdensitymadefewernon‐worksingleoccupantvehicletrips.91
Theauthorofahighlycriticalreviewofthebodyofliteraturethatattemptstoexplainlinkagesbetweenlanduseandtravelbehaviorarguedthatthereislittleevidencetosupporttheargumentthaturbanformcanpredictorinfluencetravel92andthatit’sdifficulttoisolatewhetheraspecificvariableunderconsiderationactuallyhasacausalrelationshipwiththeindependentvariable.93Thearticlegoesontosuggestthatstudiesinthiscategorycanbemoreeffectiveifresearchersuseappropriategeographicscalesandaccountforpeoples’decisionsaboutwheretolive.94
Theimpactofparkingrequirementsonurbandesign
Thereisalsoasmallgroupofworkthatstudiestheimpactofparkingonurbandesign.Sinceparkingrequirementscreatelowerdensities,theyessentiallycontrolgrowth.
85LawrenceD.FrankandGaryPivo,“ImpactsofMixedUseandDensityonUtilizationofThreeModesofTravel:Single‐OccupantVehicle,Transit,andWalking,”TransportationResearchRecord,no.1466(1995):51‐52.86SanFranciscoPlanningandUrbanResearchAssociation,“RethinkingParking,”http://www.spur.org/publications/library/report/reducinghousingcostsbyrethinkingparking_110198(accessedSeptember20,2009).87G.B.ArringtonandRobertCervero,“TCRPReport128EffectsofTODonHousing,Parking,andTravel,”TransportationResearchBoard,Washington,DC:2008,25.88Ibid.,2.89MarlonBoarnetandSharonSarmiento,“CanLandUsePolicyReallyAffectTravelBehavior?”UrbanStudies35,no.7(1998):1166;RandallCrane,“TheInfluenceofUrbanFormonTravel:AnInterpretiveReview,”JournalofPlanningLiterature15,no.1(August2000):18.90BoarnetandSarmiento,1166.91BoarnetandSarmiento,1166.92RandallCrane,“TheInfluenceofUrbanFormonTravel:AnInterpretiveReview,”JournalofPlanningLiterature15,no.1(August2000):3.93Crane,8.94Crane,19.
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However,somebelievethatgrowthcontrolmeasuresshouldbeimplementedmoredirectlyinzoningpolicies,suchasfloorarearatioslimits.95Onestudylooksatthesmall,narrowlotsonSanPabloAvenueinBerkeleyandfindsthat,withminimumparkingrequirementsinplace,theamountoflandthatwouldhavetobedevotedtoparkingwouldmakedevelopmentunfeasible,orfeasibleonlybyplacingparkinginthefrontofthelotandmovingthebuildingtowardtheback.96Thismakesforpoorurbandesign,andiflandownersdecidetheydon’twanttodevelopbecauseoftheparkingrequirements,thelandwilllayvacant.97
Anotherstudylooksattheimpactthatparkingminimumshaveondowntownlanduseandresolvesthattherequirementsleadtocongestionbecause,aseachnewdevelopmentisapprovedwithaminimumnumberofoff‐streetparkingspaces,thesupplyofparkingspacesandthenumberofcarsusingthemincreasesbutthecapacityofsurroundingstreetsremainsthesame.98Thiscreatesneighborhoodsthatarecongestedandunpleasantforwalking.Also,parkinglotentrancesanddrivewaysrequireadditionalsidewalkcurbcutsandreducespaceforstreettrees,leadingtoalesspleasantpedestrianexperience.99
Theimpactofparkingrequirementsonhousingaffordability
Theimpactofparkingrequirementsonhousingaffordabilityisoneofthemoststudiedaspectsofminimumparkingrequirements.Thebodyofliteraturedescribesthewaysinwhichminimumparkingrequirementsmakehousinglessaffordable,contributestosprawl,andamountstoinequitabletreatmentofpeoplewhodonotowncars. Thereareamultitudeofstudiesthatestimatethecostofaparkingspace.100Althoughmanyofthesestudiesareseveralyearsoldandthenumberswouldhavetobeadjustedforinflation,theyarestillinstructiveindicatorsofhowparkingincreasesthepriceofhousing.A2005studyofTODsfoundthateachunithad1.41spaces,equalingroughly$16,920,acostthatisfactoredintorentsorpurchaseprices.101TworecentstudiesofparkingcostsinSanFranciscoestimatethataparkingspaceaddsabout20%tothecostofahousingunitandcancostanywherefrom$20,000foranabovegroundspaceto$100,000foranundergroundspace.102
Thehighcostofparkingispassedontotheconsumerthroughanincreasedsalesprice.Asearlyas1964,astudyofapartmentconstructioninOakland,Californiafoundthatoncethecityestablishedminimumparkingrequirement,developersbeganbuildinglargerunitsandcharginghigherrentstopassthecostofparkingconstructionontorenters.103A95Willson(1995),39.96Cherryetal.,208.97Ibid.98MichaelManvilleandDonaldShoup,“Parking,People,andCities,”JournalofUrbanPlanningandDevelopment131,no.4(December2005):244‐5.99Henderson,77.100Henderson,78;WenyuJiaandMartinWachs,“ParkingRequirementsandHousingAffordability:CaseStudyofSanFrancisco,”TransportationResearchRecord,no.1685(1999):158;Klipp,25;Litman(January1999),9;Russo,7‐8;Shoup(1997),6;Willson(2005),83.101Willson(2005),83.102Henderson,78;Klipp,25.103WallaceF.Smith,TheLowRiseSpeculativeApartment,Berkeley:UniversityofCalifornia,BerkeleyCenterforRealEstateandUrbanEconomics,InstituteofUrbanandRegionalDevelopment,1964.
21
morerecentstudyofthecostofhousinginSanFranciscowithandwithoutparkingspacesfoundthatsingle‐familyhomeswithparkingcost11.8%morethanthosewithoutparking,andcondominiumswithparkingcost13%morethanthosewithoutparking.104Theauthorsdeterminedthatthemortgageneededtopurchaseahomewithoutparkingwouldbe$9,000lessthanwhatabuyerwouldneedtopurchaseahomewithparking,meaning24%morepeoplecouldaffordtopurchaseahomeifitdidn’tincludeaparkingspace.105A2004studyestimatesthataparkingspacecosts$68,000inSanFrancisco.106
Parkingrequirementsalsogenerallydecreasetheamountofaffordablehousingthatcanbebuilt.Developers’profitsdecreasewithhighminimumparkingrequirements,becausecostsincreaseandunitcapacityonthelanddecreases.Developerstypicallyrespondbybuildingmoreexpensiveunits,whichcanmoreeasilyabsorbthecostofparking,anddecreasethenumberofaffordableunitsbuilt.107Also,parkingrequirementsincreasetheamountofthegovernmentsubsidythatisneededforeachunitofsubsidizedhousing.108
Parkingrequirementsalsoencouragesprawlanddecreaseddensity.Whenparkingrequirementsincreasefromzerospacestoonespace,urbandevelopmentbecomesmoreexpensiveby22%whilesuburbandevelopmentonlygoesupby6%,109makingsuburbandevelopmentcheaperandmoreattractive.Also,theneedtobuildparkingonthelotlimitstheamountofhousingthatasitecanaccommodate.110Typically,developerschoosetobuildlesshousingwhenthereisaparkingrequirement,whichdecreasesdensityandcreatesfewerunitsthatcanabsorbthecostofparking.111 Finally,parkingrequirementsareinequitableforpeoplewhodonotowncars.Agreaterpercentageoflowerincomepeopledonotownvehicles.In1990,theaveragenumberofhouseholdvehiclesintheBayAreawas1.76.112Forhouseholdsearningbetween48%and60%ofthemedianincome,itwas1.3.113Householdsearningbetween24%and26%ofthemedianowned.98vehiclesonaverage.114Minimumparkingrequirementscausepeoplewhodonotowncars,andwhocannotaffordtheminsomecases,tosubsidizethecostofparkingforthosewhodoowncarsbecausethecostofparkingisbuiltintorentalratesandproductprices.
Developers’perceptionsofparkingrequirements
Developersfollowastrictsetofguidelinestoensurethatprojectswillbefinanciallysuccessfulandtheywillbeabletosecurethefundingtheyneed.Theytendtowardcautionintheirinvestmentsandavoidtakingunnecessaryrisksbecausepotentialfundersconsider104JiaandWachs,158.105Ibid.106Klipp,22.107ToddLitman,“ParkingRequirementImpactsonHousingAffordability,”VictoriaTransportPolicyInstitute(January2009),13.108ToddLitman,ParkingManagementBestPractices.Chicago:AmericanPlanningAssociationPress,2006:262;Henderson,78.109Russo,7‐8.110Ibid.111Henderson,78.112Russo,14.113Ibid.114Ibid.
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aproject’sexpectedrateofreturn,whichcanbeaffectedbyunitsinthemix,location,localamenities,andthenumberofparkingspaces.115Commercialsuccessisusuallybasedonwhetheradevelopercomplieswithcityregulations,thelocationofthedevelopment,1:1parking,andbuildingaunitmixthathasalreadyproventosellintheneighborhood.116Overcomingindustrystandardsgoverningtheamountofparkingfinanciersareconfidentwillenableaunittosellcanbechallengingforplanners.
Developmentindustrystandardsarewhy,evenifdevelopersexpectthatproximitytorailwillinfluencetravelbehavior,theyarecautioustoprovidelessparkingneartransit.117Developersinsistthathousingwithoutparkingsellsataslowerratethanhousingwithparking,118buttheJiaandWachsstudyfindsthatpeoplearewillingtopurchasearesidentialunitevenifitdoesnotincludeaparkingspace.119Specifically,thatstudyfindsthatcondoswithparkingtook41dayslongertosellthancondoswithout.120
Willson(2005)foundthatthetidesarebeginningtochange.Asdowntownareasincitiesarebeginningtoeliminateminimumparkingrequirements,developersareshowingagreaterwillingnesstoreducethenumberofspacestheybuild.121Heisconfidentthatasdevelopersseemoreexamplesofsuccessfuldevelopmentsbuiltwithlessparking,theywillbemorewillingtoapproachprojectswithlessparking.122AnotherstudyexaminedwhetherreducingparkingminimumsinTorontowouldencouragedeveloperstobuildlesscommercialparking.123Theyfindthatmanycommercialspaces,suchasoffice,generalretail,andmedicallanduses,weremorelikelytoprovidelessparkingthannecessary.AlthoughlimitedtoToronto,thisfindingsuggeststhatdevelopersmightbewillingtoprovidelowerlevelsofparkingforsomeusesiflowerminimumsareinstituted.124
Thepublic’sperceptionsofresidentialparking
AsthegovernmentinGreatBritainbegantoconsiderreplacingresidentialoff‐streetparkingminimumswithmaximumsof1.5spacesperunit,severalstudiesofpublicopinionwereconductedtodetermineoptimallevelsofparkingandhowthepopulacewouldrespondtoreductionsinparkingavailability.Respondentsinoneauto‐orientedsuburbcitedsafetyandproximityofparkingspacestotheirhomeasmainconcerns,andtheauthorsconcludedthathighparkingratiosshouldbeinstitutedtomeetcarownershipratesandhighratesofvisitors–suchas1.25parkingspacesper1‐bedroomapartment,and2.25forsemi‐detachedhomes.125
115Klipp,6.116Ibid.117Willson(2005),86.118Klipp,27.119JiaandWachs,159.120Ibid.121Willson(2005),86.122Ibid.,87.123JoshuaEngel‐Yan,BrianHollingworth,andStuartAnderson,“WillReducingParkingStandardsLeadtoReductionsinParkingSupply?:ResultsofExtensiveCommercialParkingSurveyinToronto,Canada,”TransportationResearchRecord,no.2010(2007):102.124Engel‐Yan,Hollingworth,andAnderson,109.125NobleandJenks,62.
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Anotherstudywasconductedin2002toassesstheattitudesofSoutheastLondonresidentsandresidentsofnearbysuburbstowardoff‐streetresidentialparking.12699%ofrespondentssaidtheyhadadedicatedoff‐streetparkingspaceand94%ofrespondentssaidtheywouldnotconsiderpurchasingpropertywithoutanoff‐streetparkingspace.127Eventhosewithoutacarreportedthattheywouldnotbeinterestedinhousingwithoutparking.128Whenaskedwhatfactorswouldencouragepeopletoliveinaunitwithoutaparkingspace,theyrespondedthatproximitytotransit,shops,andfacilitiesandlocationcouldswaytheiropinions.129Stubbsconcludedthatresidentsdidnotsupportpoliciestoeliminate1:1parkingbecausetheywereworriedthathousingwithoutparkingwouldbeworthlessandbecauseofthepotentialinconvenienceassociatedwithnothavingapersonalparkingspace.130Althoughtheseresultsareveryinteresting,theyarelimitedingeographicscopeandsamplesize,asonly47peopleinandaroundLondonresponded.131
Alternativestominimumparkingrequirements
Manystudieshaveputforthsuggestionsforalternativepoliciesandpracticesthatcanhelpaddresssomeoftheproblemsthatthecurrentparkingminimumparadigmcreates.Abriefdiscussionofeachalternativepolicyfollows.
Somestudiessuggestthatcitiesshouldadoptparkingmaximums,whichwouldreplacetherequiredminimumnumberofspaceswithamaximumnumberofspaces,overwhichadevelopercouldnotprovideadditionalparking.132AsmallsurveyofgovernmentsinScotlandrevealedsupportforthepotentialofparkingmaximumstoreducecaruseandstimulatedenserdevelopment,andevensomesupportfromdevelopers.133
Alargegroupofstudiesadvocatesfortheunbundlingofparkingfromthecostofpurchasingorrentingahome.134“Unbundling”meansthatparkingspacesareavailableataresidentialbuildingforpurchaseorrent,butarenotautomaticallyincludedinthesalepriceofthehome.Thesestudiesarguethatparkingrequirementshidethetruecostofdriving,135whichsubsidizesdrivingandencouragespeopletodrivemoresinceitappearstobearatherinexpensiveformoftravel.Also,whenparkingisbundledwiththepriceofhousing,developerscan’tmeasurethemarketdemandforit.136Unbundlingparkingcoulddecreasethecostofhousingandensurethatthosewhousetheparkingspacesaretheones
126MichaelStubbs,“CarParkingandResidentialDevelopment:Sustainability,DesignandPlanningPolicy,andPublicPerceptionsofParkingProvision,”JournalofUrbanDesign7,no.2(2002):213.127Ibid,232.128Ibid,228.129Ibid,232.130Ibid,234.131Ibid.,213.132Cherryetal.,209.133RyeandIson,11‐12.134Litman(January2009),2;Klipp,30;Russo,11;SPUR(2004);SanFranciscoPlanningandUrbanResearchAssociation,“ParkingandLivabilityinDowntownSanFrancisco:PoliciestoReduceCongestion.”www.spur.org/publications/library/report/parkingandlivabilityindowntownsf_010105(accessedSeptember27,2009);Willson(2005),83.135Russo,11;SPUR(2004)136Willson(2005),83.
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whopayforit.137Thereissomeevidencethat,althoughinitiallyresistant,developersarebecomingmoresupportiveofunbundlingparking.138
Manypapersadvocateforreducingparkingrequirements,eitherinconjunctionwithaparkingmanagementprogram,139orbycreatingreduced,context‐specificparkingrequirementsforTODs140andaffordablehousing.141Russodescribesaparkingmanagementsystemforprovidingoff‐streetresidentialparkingwhereinprojectswouldbeapprovedwithlowerparkingminimums,butdeveloperswouldberequiredtoprovidelandscapedareasthatcouldlaterbeconvertedtoparking.142Inconjunction,thecitywouldrequirethedevelopertofundtransitpassprogramsforresidentsanditwouldrestrictstreetparkingpermitsforresidentstoreducespilloverimpacts.143Engel‐Yanadvocatesforreducedparkingminimumsinconjunctionwithaparkingmanagementprogramthatconsidersenvironmental,economic,andtransportationsystemconcerns.144
SeveralstudieslayoutframeworksforreducingparkingrequirementsforTODandaffordablehousingunits,whichtendtoattractpeoplewhoeitherprefertoliveneartransitandwithoutacar,orwhoareconstrainedtoliveassuchduetotheirfinancialsituation.145ArringtonsuggeststhattheITEParkingGenerationhandbookadoptalternaterequirementsspecificallyforTOD,whichshouldbemoreflexiblethanthestandardparkingrequirementsandallowforreducedparkingatTODs.146Anotherstudysuggeststhatthedemographiccharacteristicsofaproposeddevelopment’slikelyinhabitants,suchasage,income,disabilitystatus,147andcarownershiprates148betakenintoconsiderationwhenassigningparkingrequirements.
Sharedparkingfacilitiesarefrequentlymentionedinconjunctionwithcommercialparkingfacilities,buttheycanalsobeusedtoaddressissueswithresidentialparking.149TODscanpartnerwithtransitagenciestoshareparkingneartransitstations,sincethetwolandusesrequireparkingatdifferenttimesofday.150Sharedparkingisperceivedassaferthandedicatedparkinganditmakesthebestuseofdrivewayspace,requiresthatlessoverallparkingbeprovided,andcanhelpincreasehousingdensities.151Sharedparkingprovidestheaddedbenefitofenablingunderutilizedparkinglotstolaterbeconvertedtocommunalspaceifparkingdemandislaterreduced.152
Designsolutionscanhelpalleviatesomeofthenegativeaestheticimpactsofparkinglots.Innovativedesignsolutionsliketandemparkingandcarelevatorscanreducethe
137SPUR(2004).138Klipp,30.139Engel‐Yan,Hollingworth,andAnderson,110;Russo,24.140ArringtonandCervero,54;SPUR(2006),3;Willson(2005),90.141Russo,20;SPUR(2006),4‐5.142Russo,21.143Russo,21‐24.144Engel‐Yan,Hollingworth,andAnderson,110.145SPUR(2006),3.Willson(2005),90.146ArringtonandCervero,54.147Russo,20.148SPUR(2006),4‐5.149Cherryetal.,209;Russo,25.150Willson(2005),90.151NobleandJenks,65‐66.152Ibid.
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amountofspacededicatedtoparking,153thoughthisclassofsolutiondoesnotaddresstheprevalenceofsingleoccupantvehiclesincities.Improvingthephysicaldesignofparkinglotsbydroppingthemafewfeetbelowpedestrianlevelandaddingsolarpanelsorlandscapingcanhelpcreatemorepleasanturbanexperiences.154Forparkinggarages,designsolutionsincludewrappingthegaragewithretailshops,makingthegaragelooklikeabuilding,andplacingparkingonlyonupperlevels.155Forsingle‐familyunits,citiescanrestrictthesizeofgaragedoorsthatfacethestreettoonlythewidthofasinglecar,requirethatagaragedoortakeuplessthan50%ofabuilding’sfaçade,orrequirethatdevelopersplaceparkingattherearofthehouse.156
Finally,agroupofinnovativealternativestoparkingminimumshasdeveloped.Thesesolutionsshouldn’tnecessarilybeusedinisolation,butincombinationwithoneofthepolicieslistedabovecouldbequiteeffectiveatreducingsomeoftheimpactsofrequiredparking.Thesesolutionsincludecar‐sharingprogramsthatmakevehiclesavailableforshort‐termrentalrightatdevelopments,157development‐widetransitpasses,158andin‐lieufeesthatcanbeusedtobuildcommunalparking.159
IntheminorityofresearchregardingparkingpolicyisonearticlearguingthatminimumparkingrequirementsarenotresponsibleforincreasesinVehicleMilesTraveled(VMT)and,infact,haven’tkeptpacewithincreasesincarownership.ThispaperstatesthatcarownershipintheUnitedStatesincreasedbyabout200%between1946and1990,butVMTonlyincreasedby18%andminimumparkingrequirementshaven’tevendoubled.160Althoughtheauthordoesn’tofferevidencetosupportthisclaim,hesuggeststhatonlyone‐thirdoftheincreaseinVMTcanbeattributedtoparkingrequirements,andsuggeststhatVMThasincreasedinrecentyearsbecauseofsprawlandlongerperiodsofpeaktravel.161
ConclusionsFromtheLiterature Thebodyofresearchregardingtheinfluenceofresidentialparkingspaceavailabilityontravelbehaviorisratherthin,andevenstudiesinrelatedareassuchastheeffectsofparkingonmodechoiceforworkandshoppingtripsaresomewhatlimited.Theliteraturedescribinghowurbanforminfluencestravelbehaviorisinconclusive,andsomeresearcherssaythaturbanformfactorscannotbeusedtopredictormeasuretravelbehavior.Theliteratureregardingtheinfluenceofparkingrequirementsonhousingpricesisalittlebitbulkier,withageneralagreementthatparkingrequirementsareexpensive,andtheyraisethecostofhousingandcannegativelyinfluencedensity.
153Klipp,32‐33;Russo,26.154VinitMukhijaandDonaldShoup,“QuantityversusQualityinOff‐StreetParkingRequirements,”JournaloftheAmericanPlanningAssociation72,no3(Summer2006):302.155Ibid.,303.156Ibid.,305.157Klipp,35;Russo,24.158Russo,25.159Cherryetal.,209;Russo,25;MukhijaandShoup,299.160ErikFerguson,“ZoningforParkingasPolicyProcess:AHistoricalReview,”TransportReviews24,no.2(March2004):188.161Ibid.,189.
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Manyresearchersinthisareahavenotedtheneedforadditionalresearchontopicsrelatedtoparkingandtravelbehavior.Researchersarestartingtotakenotethatparkingisbyandlargeunderstudiedandomittedfrommostplanningcurricula.162Futureresearchissuggestedtounderstandhowpeoplewillreacttotheintroductionofparkingmaximumsthatcouldleadtoreductionsintheavailabilityofoff‐streetresidentialparkingspaces.163Also,moremustbelearnedabouthowparking,particularlyresidentialparking,164influencesmodechoiceonasmallergeographiclevel,possiblytheblockgrouplevel.165Finally,anyresearchaboutresidentialtravelbehaviormustincludeconsiderationofwhetherpeoples’housingpreferencesallowthemtoself‐selecttotravelandliveincertainlocations,whichisanotherareaofresearchaboutwhichlittleisknown.166 Thisstudyfitswellintotheresearchvoidconcerningtheinfluenceofresidentialparkingspaceavailabilityontravelbehavior.Sinceverylittlecomprehensiveresearchhasbeendoneinthisarea,Ithinkthattheresultsofmysurveyshouldhelpinformthebodyofresearchthatdescribestheimpactofbothparkingandlanduseontravelbehavior.Ialsointendtoaddresswhetherpeopleself‐selecttoliveneartransitorinacertainlocation,soIexpectthisstudytoexpandtheliteratureinthatareaoffocusaswell.Itismyhopeandexpectationthatmyanalysiswillhelptoshedlightonthisunderstudied,yetimportant,aspectofparkingpolicy.
162Henderson,73.163Stubbs,235.164JiaandWachs,159;Marsden,455.165FrankandPivo,52.166BoarnetandSarmiento,1162;Marsden,455.
ASurveyoftheInfluenceofResidentialParkingAvailabilityonTravelBehavior
SurveyMethodologyAlthoughtheeliminationofminimumoff‐streetparkingrequirementsandthe
implementationofparkingmaximumsinresidentialareasareseenastwomethodsforlimitinguseofmotorvehiclesandforreducingcongestiononcitystreets,verylittleresearchhasbeenconductedtodeterminewhethertheresidentsofthesetwotypesofneighborhoodsmaybepre‐inclinedtowardlessfrequentuseofautomobilesorwhetherthesepoliciesmaypotentiallybesuccessfulinencouragingpeopletochangetheirtravelpreferences.Assuch,asurveywasconductedaspartofthisstudytodetermine:
1. Theextenttowhichtheavailabilityofanoff‐streetresidentialparkingspace
influencesresidents’travelbehaviorinSanFrancisco.2. Whetherreducingresidentialoff‐streetparkingrequirementsencourages
peopletodriveless.Priortothisstudy,therewaslittletonoinformationavailabletodescribetheextent
towhichthetravelbehaviorofSanFranciscoresidentswithaccesstoanoff‐streetparkingspaceathomevariedfromthatofSanFranciscoresidentswithoutaccesstoan‐offstreetparkingspaceathome.NeithertheUnitedStatesCensusnortheAmericanCommunitySurveyincludesquestionsaboutresidentialparking.AlthoughtworecentsurveysconductedinSanFranciscoincludedquestionsaboutparkingavailabilityathome,bothcoveredlimitedgeographicareasthatwouldnotprovideusefuldatacomparisons.167
Thus,primarydatawasneededtoanswertheresearchquestionposedinthisstudy.Asurveyisanappropriatemethodforgatheringdataonquestionsoftravelbehaviorandattitudesbecauseitcanyieldqualitativedatathatothermethodsofdatacollectiondonotconsider.Manypreviousstudiesoftheinfluenceofparkingontravelbehaviorhaveusedsurveystogatherdata.168
Althoughthesurveymethodisanextremelyaccurate,inexpensive,andfastmethodforcollectingdataabouttravelbehavior,itisnotwithoutitschallenges.Attimes,surveysamplesmaybetoosmallorunrepresentative,ormemory,recency,orconsistencybiases
167RoccoPendola,StephanieRuddy,andElmerTosta,“ResidentialParkingRequirementsinSanFrancisco:DoTheyAffectTravelBehavior?”UnpublishedreportpresentedtoLivableCitybySanFranciscoStateUniversityUrbanStudiesProgram,May2005;SanFranciscoPlanningDepartment,“ResidentTravelBehaviorSurvey:SOMA/TransbayArea,”ResearchconductedbyGodbeResearch,December2008.168Engel‐Yan,Joshua,BrianHollingworth,andStuartAnderson.“WillReducingParkingStandardsLeadtoReductionsinParkingSupply?:ResultsofExtensiveCommercialParkingSurveyinToronto,Canada.”TransportationResearchRecord,no.2010(2007):102‐110;Pendola,Rocco,StephanieRuddy,andElmerTosta.“ResidentialParkingRequirementsinSanFrancisco:DoTheyAffectTravelBehavior?”UnpublishedreportpresentedtoLivableCitybySanFranciscoStateUniversityUrbanStudiesProgram,May2005;Stubbs,213.
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mayexist.169Thesurveymethodalsomakesitdifficulttoquantifyhowpeoples’tendencytowardself‐selectionofresidentialcharacteristicsbasedonpre‐heldattitudesmayinfluencetheirtravelbehavior.170Onestudystatesthatexperimentsconductedtomeasuretheinfluenceofachangetothebuiltenvironmentontravelbehaviorareamongthemorereliablemethodsofestablishingarelationshipbetweentravelbehaviorandthebuiltenvironment.171Althoughtheexperimentalmethodmayachievemorevalidresultsthanthesurveymethod,abeforeandafterexperimentwouldbeoutsidethepurviewofthisstudybecauseoffundingandtimelimitations,andthedifficultyofidentifyingappropriateexperimentlocationsinSanFranciscoduringthecurrentconstructionslowdown.
SurveyInstrument
Ibasedthesurveyinstrument(Appendix1)onquestionsthatotherresearchersstudyingtravelbehaviorincludedintheirsurveysandonquestionsthatareincludedintheNationalHouseholdTravelSurvey.172Ithentailoredthequestionstomorespecificallycollectthequalitativedatathatmyresearchquestionsrequire.Iincludedaquestionprobingthereasoninginformingpeoples’decisionstoliveinspecificlocations,toaddressandlimitthepossibilitythatpeoplemayself‐selectwheretheylivebecauseofdeep‐heldideologies,attitudes,andpreferences.Thesurveyaskedsubjectstonotethecrossstreetsthatareclosesttotheirhometodeterminewhethertheyliveinanareawithorwithoutaparkingmaximum.Finally,Iaskedpeers,colleagues,andmyfacultyadvisortoreviewthesurveyandprovidefeedbackandsuggestionsforimprovements.
SampleSelectionandSurveyAdministration
ThesamplepopulationforthesurveyincludesSanFranciscoresidentswholiveinneighborhoodswhereparkingmaximumshavebeenenactedandacontrolgroupofthosewholiveinneighborhoodswhereparkingmaximumshavenotbeenenacted.Thefocusisonthedenseinnerurbanareaswhereparkingmaximumshaverecentlybeenenactedbecauseparkingspaceavailabilityismorelikelytohaveaninfluenceonthetravelbehaviorofresidentsintheseneighborhoodsthanthosewholiveinthemoresprawling,lesstransit‐accessibleouteredgesofthecitywhereparkingminimumsstillapply.Icollecteddatafromneighborhoodsthatdonothaveparkingmaximumsinplacetocomparedifferenceswithinthetwogroups.Figure1indicatesthecross‐streetsclosesttotheresidencesofsurveyrespondentswholiveneardowntownSanFranciscoandtheboundariesofthevariousneighborhoodswhereresidentialparkingmaximumshavebeenenacted. Thesurveywasadministeredto203subjectswhoareSanFranciscoresidentsaged18orolder.19responseswereeliminatedbecausetheyprovidedincompleteinformationandtworesponsesweredeletedbecausetheywereduplicates.Thus,thestudysampleyielded182complete,uniquesurveysthatcouldbeanalyzed.Thesurveywasadministered169PatriciaL.MokhtarianandXinyuCao,“Examiningtheimpactsofresidentialself‐selectionontravelbehavior:Afocusonmethodologies,”TransportationResearchPartB:Methodological42,no.3.(2008):207‐208.170Ibid.,205,211.171Ibid.,225‐226.172UnitedStatesDepartmentofTransportation,“NationalHouseholdTravelSurvey,”BureauofTransportationStatistics,ResearchandInnovativeTechnologyAdministration,UnitedStatesDepartmentofTransportation,www.bts.gov/programs/national_household_travel_survey(accessedFebruary23,2010).
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asbothanin‐personinterceptsurveyandasanonlinesurveytoarandomsamplebetweenFebruary28,2010andMarch21,2010.TheinterceptsurveywasadministeredatthelocationsandonthedatesindicatedinTable2.Table2.Locations,Dates,Times,andSampleSizeofInterceptSurveyAdministrations
Location Date Time SampleSize
SOMAWholeFoodsGroceryStore,4thSt.andHarrisonSt. Sat.2/29 9:00am‐10:30am
13
RainbowGrocery,13thSt.andFolsomSt. Sat.2/29 11:00am–2:00pm
37
MissionCreekPark,4thSt.andChannelSt. Sat.3/6 11:30am‐2:00pm
14
DoloresPark,18thSt.andDoloresSt. Sat.3/6 3:00pm–5:00pm
17
NoeValleyWholeFoodsGroceryStore,24thSt.andNoeSt. Sun.3/7 9:00am‐10:00am
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TOTAL=106
Alllocationsaretransit‐accessible.TheSOMAWholeFoods,RainbowGroceryStore,andMissionCreekParkarewithinparkingmaximumareas;theNoeValleyWholeFoodsandDoloresParkarenotwithinparkingmaximumareas.Atthestorelocations,subjectswererecruitedastheyenteredorexitedthestore,orastheywalkedbyonthestreet.Thesurveyswereself‐administeredandfilledinonclipboards.Severalvolunteerstrainedinpropersurveyadministrationprotocolandprovidedwithanoverviewoftheproject’sobjectivesassistedtheprincipalinvestigatorwithdatacollection.Volunteersalsoworebuttonsthatidentifiedthemas“GraduateStudentResearchers”affiliatedwithSanJoseStateUniversity.
ThesamplealsoincludedSanFranciscoresidentsfromotherpartsofthecity,whocompletedthesurveyonline.TheGlenParkAssociationandHayesValleyNeighborhoodAssociationdistributedthesurveylinktotheirmembersviaemail,andseveralvolunteerspostedthesurveylinktothesocialnetworkingsiteFacebookorsentemailedinvitationstocolleagues.TheHayesValleygroupislocatedminutesfromtheSanFranciscoCivicCenterinanareawithoutresidentialparkingminimumsandwithparkingmaximums;theGlenParkgroupislocatednearthesouthernedgeofthecityinaneighborhoodwithaBARTstation.GlenParkstillhasresidentialparkingminimumsandnoparkingmaximums.Contactsineachoftheseorganizationscirculatedalinktomemberswitharequestidentifyingthestudyasstudentresearchandrequestingthattheycompletethesurveyonlineathttp://www.surveygizmo.com/s/251929/jnarg.
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Figure1.MapofSurveyRespondentsandAreaswithParkingMaximumsinSanFrancisco.
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Market Octavia Neighborhood Plan AreaMission Bay Redevelopment Plan AreaRincon Hill Plan Area = Location of survey respondent’s residence
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31
IssueswithSurveyAdministration
Althoughthesamplewasrandomtoavoidsamplingbias,thereweresomeissueswithself‐selection,affinity,andaccessibilitybias.IoriginallyplannedtodeliverthesurveyoutsideofabusySafewaystoreattheintersectionof4thStreetandKingStreetinSOMA,andwasignoredbyeverypersonwhowalkedbyfor10minutes,despitemycleanappearanceandanintroductorylineandabuttonidentifyingmeasastudentconductingresearchforaschoolproject.Thereareanumberofpanhandlerswhotypicallyoperateinthisarea,sothisresponseisunderstandable.Asaresult,ImovedtonearbyMissionCreekPark,whereIhadahigherresponserate.IoriginallywantedtoincludeSafewaystoresinmyanalysisbecausethesupermarket’spricesarelowerthanthoseatWholeFoods,whichmighthaveprovidedamorebalancedsurveysample.
Aswithallinterceptsurveys,atouchofaffinitybiasalsoenteredthepicturebecausewetendednottoapproachpeoplewhowereinvolvedinconversation,talkingonacellphone,listeningtoheadphones,orwhodisplayedobviousdisinterestbywalkingquicklypastusoravertingtheirgaze.Wealsodidnotapproachpeoplewhowerewalkingdogsifanotherpersonwithadogwasalreadycompletingthesurveyinthearea,toavoidconflictsbetweentheanimals.Finally,duetothetimeandresourceconstraints,wecouldnotaccessallareasofthecity,whichcouldhaveintroducedsomeaccessibilitybiasaswewereunabletorepresentallpossiblesituations.Assuch,Ireachedouttothemostaccessiblesubjects,whicharethosewhowerepresentatpublicareasthatIcouldreadilyaccessandwhoself‐selectedtocompletethesurvey,orthosewhosubscribetoneighborhoodlistservsandarethusalreadypre‐disposedtocivicmindedness.
SurveyResultsThefinalsamplesizewas182,with65respondentsfromareaswhereparking
maximumshavebeenimplementedand114wholiveinareasofthecitywhereresidentialparkingminimumsarestillinplace.Threerespondentsdidnotindicatewheretheylive.Table3displayssurveyrespondentdemographics.Table 3. Demographics of Survey Respondents
YearofBirth1971to1992 1945to1970 1944andearlier NoAnswer
61.5% 31.3% 2.7% 4.4%Income
$36,000orless $36,001to$75,000 $75,001to$150,0001 $150,000andgreater19.2% 18.7% 24.2% 26.9%
GenderMale Female Self‐Identified 49.5% 47.3% .6%
Numberofadultsinhousehold1 2 3 4ormore
28% 47.3% 11.5% 8.2%Numberofchildreninhousehold
0 1 2 3ormore82.4% 6% 6% 2.2%
HomeOwnershipRent Own 58.8% 37.9%
32
Analysisofthesurveyresponsesyieldedthefollowingstatisticallysignificantresults:Peoplewholiveinareaswhereparkingmaximumshavebeenintroducedmakefewerworktripsinsingle‐occupantmotorvehiclesthanthosewholiveinareaswithoutparkingmaximums.Thereisalsoarelationshipbetweenavailabilityofanoff‐streetresidentialparkingspaceandthechoiceofsingle‐occupantvehicleastheprimarymodeforworkcommutes.Also,thereisarelationshipbetweenavailabilityofanoff‐streetparkingspaceathomeandmodechoiceforentertainmenttrips.
Intermsofoveralltrips,peoplewithoutanoff‐streetresidentialparkingspaceavailableattheirhomereportedmaking,onaverage,1.4tripsbybicycleeachday.Thisiscomparedtothe.5tripsperdaythatpeoplewhohavemotorvehicleparkingathomereport.Availabilityofaparkingspacewasnotcorrelatedwithmodechoiceforothermodeswithstatisticalsignificance,butpeoplewhohaveaparkingspaceathometookanaverageof2.2tripsbyvehicleperday,ascomparedtothe1.5tripsperdaymadebypeoplewithoutaparkingspaceavailableathome.
Finally,peoplewholiveinareaswithparkingmaximumsalsomakemoretripsbybicycleeachday.Thosewholiveinareaswithparkingmaximumsreportedmaking1.8tripsbybicycleeachday,asopposedtothe.6tripsperdaythatpeoplewholiveoutsideofparkingmaximumareasreported.Also,peoplewholiveinareaswithmaximumsmakeanaverageof2.2tripsbysingleoccupantmotorvehicleeachday,comparedtothe.86tripsbymotorvehiclethatpeoplewholiveinparkingmaximumareasmake.Inthenextsection,Iwilldescribeingreaterdetailthemethodsutilizedinthisstudytodeterminetheseresults.
StatisticalAnalysis
InSanFrancisco,towhatextentdoestheavailabilityofanoff‐streetresidentialparkingspaceinfluenceresidents’travelbehavior?
Theprimaryfocusofthispaperconsiderstherelationshipbetweenaccesstoanoff‐streetresidentialparkingspaceandtravelbehavior.Toaddressthisissue,severalresearchquestionsweredevelopedtoanalyzethesurveydatausingPASWStatistics18.0.Thesurveyrespondentswerecodedbasedonwhetherornottheyhadaccesstoanoff‐streetparkingspaceattheirresidence,regardlessofwhethertheyownamotorvehicle.Thesamplewasrelativelyevenlysplit,with86respondentswhodonothaveaccesstoanoff‐streetresidentialparkingspaceand79respondentswhodohaveaccesstoanoff‐streetresidentialparkingspace.
Thefirstresearchquestionwas:“Whetherpeoplewhohaveanoff‐streetresidentialparkingspacemakemoreworktripsbysingleoccupantvehiclethanthosewhodonothaveanoff‐streetresidentialparkingspace.”ThisquestionwasanalyzedusingaT‐testforindependentsamples,whichfoundthat
peoplewithaccesstoanoff‐streetparkingspaceathomemakeanaverageof.89tripstoworkbysingleoccupantvehicle,whilepeoplewithoutaccesstoanoff‐streetparkingspacemakeanaverageof.64tripsbymotorvehicleperday.Thisresulthadapvalueof.172,
33
whichisgreaterthanthecriticalvalueof.05,whichmeanstheresultisnotstatisticallysignificant.
Next,Two‐Factor‐Chi‐Squaretestswereutilizedtoanalyze“whetherthereisarelationshipbetweenavailabilityofanoff‐streetresidentialparkingspaceandprimarycommute,errand,andentertainmentmodes”Forthepurposesofthisstudy,“primarymode”wasdefinedas“themodeusedforthelongestpartofthetrip.”
Respondentswereaskedtoidentifythemodetheyconsideredtheirprimarymodefortraveltoworkorschool,forerrandssuchasshopping,andentertainmentsuchasatriptothemovies,fromalistthatincludedbicycle,carshare,singleoccupantmotorvehicle,carpool,publictransit,walking,orother.
Asforcommutemode,themajorityofrespondentsreportedcommutingbysingleoccupantvehicle(55),publictransit(46)orbicycle(26).Table4belowdisplaysthebreakdownsproducedbythistest.Table 4. Off-Street Residential Parking and Primary Commute Mode Cross-Tabulation
PrimaryCommuteMode
Bicycle
MotorVehicle(SOV)
MotorVehicle(Carpool)
PublicTransit Walking
Workat
Home Other Total
No 20 23 3 21 8 8 0 83Off‐StreetResidentialParking
Yes 6 32 3 25 3 4 2 75
Total 26 55 6 46 11 12 2 158Forentertainmenttrips,peopleprimarilyreporteddrivingsingleoccupantmotor
vehicles(46),ridingpublictransit(38)orwalking(33).Table5belowdisplaysthebreakdownsforentertainmenttrips.Table 5. Off-Street Residential Parking and Primary Entertainment Mode Cross-Tabulation
PrimaryEntertainmentMode
Bicycle
MotorVehicle(SOV)
MotorVehicle(Carpool)
PublicTransit Walk Other 8 Total
No 16 20 4 21 18 3 0 82Off‐StreetResidentialParking
Yes 3 26 10 17 15 1 1 73
Total 19 46 14 38 33 4 1 155AlthoughaChi‐SquareTestcanrevealcorrelationandarelationship,itcannot
determinecausality.Thus,welearnfromthistestthatthereisarelationshipbetweenavailabilityofanoff‐streetparkingspaceathomeandprimarycommutemodechoice,and
34
betweenavailabilityofanoff‐streetparkingspaceathomeandprimaryentertainmentchoice.However,wedonotknowtheprecisenatureoftheserelationships.
Thefindingforcommutemodeisstatisticallysignificantwithapvalueof.024(seeTable6below).
Thefindingforentertainmentmodeisstatisticallysignificantwithapvalueof.025(seeTable7below).Table 6. Off-Street Residential Parking and Primary Commute Mode Statistical Significance
Value df
Asymp.Sig.(2‐sided)
PearsonChi‐Square 14.597a 6 .024LikelihoodRatio 15.865 6 .014NofValidCases 158
a.4cells(28.6%)haveexpectedcountlessthan5.Theminimumexpectedcountis.95.
Table 7. Off-Street Residential Parking and Primary Entertainment Mode Statistical Significance
Value df
Asymp.Sig.(2‐sided)
PearsonChi‐Square 14.469a 6 .025LikelihoodRatio 15.812 6 .015NofValidCases 155
a.4cells(28.6%)haveexpectedcountlessthan5.Theminimumexpectedcountis.47.
ACross‐Tabulationwasalsopreparedtoinvestigatetheexistenceofarelationshipbetweenoff‐streetresidentialparkingavailabilityandprimaryerrandmode.Althoughtheresultsindicatethatmorepeoplewhodonothaveaparkingspaceathomeconsiderbicyclingtheirprimarymodeoftransportationforerrands,andfewerconsideramotorvehicleastheirprimarymode,theseresultsarenotstatisticallysignificant.TheresultofthistestisincludedinTable8andTable9below.Table 8. Off-Street Residential Parking and Primary Errand Mode Cross-Tabulation
PrimaryErrandMode
BicycleCityCarShare
MotorVehicle(SOV)
MotorVehicle(Carpool)
PublicTransit Walk Total
No 16 1 29 3 4 30 83Off‐StreetResidentialParking Yes 7 0 40 3 2 22 74Total 23 1 69 6 6 52 157
35
Table 9. Off-Street Residential Parking and Primary Errand Mode Statistical Significance
Value df
Asymp.Sig.(2‐sided)
PearsonChi‐Square 7.682a 5 .175LikelihoodRatio 8.164 5 .147NofValidCases 157
a.6cells(50.0%)haveexpectedcountlessthan5.Theminimumexpectedcountis.47.Finally,aT‐Testwasperformedtoanalyzethequestion,“Whetherpeoplewhohavean
off‐streetresidentialparkingspaceavailable{bicycle,usecitycarshare,drivesingleoccupantmoorvehicle,carpool,ridepublictransit,walk,oruseanothermode}morethanthosewhodonothavearesidentialoff‐streetparkingspaceavailableforalltripscombined.”
Thisquestionanalyzeddatacombinedfromseveralofthesurveyquestions.Thesurveyinstrument(SeeAppendix1)askedrespondentshowmanytripstheytookoneachofthemodeslistedabove.Italsoaskedrespondentstoindicatetheirprimarymodeforerrandandentertainmenttrips,andhowmanytripsperdaytheytookforeachofthesepurposesonaverage.Bycombiningaveragenumberoftripsperdayusingeachmode,a“totaltripsperdayoneachmode”valuewascalculated.Table10displaysthedescriptivestatisticsforeachmode.Althoughmanyinterestingrelationshipsarerevealed,theonlycorrelationthatisstatisticallysignificantisthatbetweenbicyclecommutetripsandavailabilityofaparkingspace.Peoplewithaparkingspaceathomemake.5tripsforworkonbicycleonaverage,whilepeoplewithoutaparkingspaceathomemakeanaverageof1.4tripsforworkviabicycleeachday.Thisfindingisstatisticallysignificantwithapvalueof.042.Table 10. Descriptive Statistics for Work Mode Share and Availability of a Parking Space at Home
GroupStatistics Off‐Street
ResidentialParking N Mean Std.Deviation
Std.ErrorMean
No 81 1.3563 3.13616 .34846BicycleWorkTrips/dayYes 69 .5138 1.42967 .17211
No 81 .0062 .05556 .00617CarShareWorkTrips/dayYes 69 .0290 .24077 .02899
No 81 1.5037 2.39551 .26617MotorVehicleWork(SOV)/dayYes 69 2.2004 2.99002 .35996
No 81 .2148 .96707 .10745MotorVehicleWork(Carpool)Yes 69 .3199 1.09823 .13221
No 81 1.1191 1.95768 .21752PublicTransitWorkTrips/dayYes 69 1.2325 1.87598 .22584
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No 81 1.7743 2.48222 .27580WalkWorkTrips/dayYes 69 1.7029 2.36950 .28525
No 81 .0370 .19003 .02111Othermode(see#4)Yes 69 .0688 .34269 .04125
Thus,itseemsthatinSanFrancisco,availabilityofanoff‐streetresidentialparking
spaceisrelatedtothemodeoftravelthatpeoplechooseforcommuteandentertainmenttrips.Althoughtheexactnatureofthatrelationshipisnotentirelyclear,itisclearthatpeoplewhodonothaveanoff‐streetparkingspaceathomecommuteviabicyclemorefrequentlythanthosewhohaveanoff‐streetparkingspaceavailableathome.
Willreducingresidentialoff‐streetparkingrequirementsencouragepeopletodriveless?
Thesecondissuethispaperaddresseslooksfortheexistenceofarelationshipbetweenresidentialparkingrequirementsandtravelbehavior.Specifically,thesurveypreparedinconjunctionwiththispaperaskedquestionsaboutthewaysinwhichpeopletravelinareaswhereresidentialparkingmaximumshavebeenimplementedandthosewheremaximumshavenotbeenintroduced.Thesequestionsseektorevealwhetherreducingparkingmaximumsmayachievetheintendedresultofencouragingpeopletodrivelessinareaswheremaximumsareintroduced. Thesurveyrespondentswerebrokenintotwogroups:onecomposedofpeoplewholiveinneighborhoodsinSanFranciscowhereparkingmaximumshavebeenintroduced,andonecomposedofpeoplewholiveinSanFrancisconeighborhoodsthatstillmaintainmoretraditionalparkingminimumrequirementsinthezoningcode.Theformergrouplivesinareasclosertodowntownthatarewell‐servedbytransit;thelattergroupisprimarilylocatedtowardtheedgesofthecityandfurtherfromdowntown. First,aT‐TestforIndependentMeanswasconductedtodeterminewhethercausalitycanbedeterminedbetweenlivinginanareawithaparkingmaximumandnumberofworktripstakenbysingle‐occupantmotorvehicle,publictransit,bicycle,andwalkingmodes.Thistestfoundwithstatisticalsignificancethatsingleoccupantmotorvehicletripsareinfluencedbyaperson’sresidenceinanareawithaparkingmaximum.Peoplewholiveinareaswithparkingmaximumsmake.87tripsforworkbysingleoccupantmotorvehicleeachday;thosewhodonotliveinareaswithparkingmaximumsmake.46tripsforworkbysingleoccupantvehicle.Thepvaluewas.022,whichislessthanthecriticalvalueof.05,meaningthisresultisstatisticallysignificant,and,thus,residencewithinanareawithparkingmaximumsseemstocausepeopletomakefewerworktripsbysingleoccupantvehicle.Althoughtheresultsforworktripsbybicycle,transit,oronfootwereinteresting,noneofthesefindingswerestatisticallysignificant. Next,aT‐TestforIndependentMeanswasconductedtodetermineifthereisarelationshipbetweenparkingmaximumsandthetotalnumberoftripsrespondentsmadeeachdayviaeachmode.Asdescribedabove,thetotalnumberoftripsthatrespondentsmadeeachdaywascalculatedbycombiningthereportednumberoftripsthatrespondentsmadeusingtheirprimarywork,errand,andentertainmentmodes. Thistestfoundthatpeoplewholiveinareaswithparkingmaximumsmade1.8tripsonbicycleperday,whilepeoplewholiveinareaswithoutparkingmaximumsmade.6tripsperdayviabicycle.Inotherwords,peoplewholiveinareaswithparkingmaximumsmake
37
3timesasmanytripsbybicycleeachdayasthosewhodonot.Thisfindingisstatisticallysignificantatthe.006level. Thetestalsofoundthatpeoplewholieinareaswithparkingmaximumsmade.9tripsbysingleoccupantmotorvehicleseachday,whilepeoplewholiveinareaswithoutparkingmaximumsmade2.2tripsperdayviasingleoccupantmotorvehicle.Inotherwords,peoplewholiveinareaswithparkingmaximumsmakefewerthanhalfasmanytripsviasingleoccupantmotorvehicleeachdayasthosewhodonot.Thisfindingisstatisticallysignificantatthe.002level. Table11belowdisplaysthefindingsofthistest.Table 11. Relationship Between Parking Maximums and Number of Trips Per Day by Mode
GroupStatistics LivesinMaximumarea?
N MeanStd.
DeviationStd.ErrorMean
NotMaximumArea 101 .6095 1.42377 .14167BicycleWorkTrips/day InMaximumArea 54 1.7694 3.71784 .50593
NotMaximumArea 101 .0050 .04975 .00495CarShareWorkTrips/day
InMaximumArea 54 .0370 .27217 .03704
NotMaximumArea 101 2.2206 3.02002 .30050MotorVehicleWork(SOV)/day
InMaximumArea 54 .8620 1.42933 .19451
NotMaximumArea 101 .3059 1.19102 .11851MotorVehicleWork(Carpool)
InMaximumArea 54 .1587 .53137 .07231
NotMaximumArea 101 1.0592 1.76650 .17577PublicTransitWorkTrips/day
InMaximumArea 54 1.3557 2.13153 .29006
NotMaximumArea 101 1.7755 2.53047 .25179WalkWorkTrips/dayInMaximumArea 54 1.6276 2.27377 .30942
NotMaximumArea 101 .0396 .24169 .02405OthermodeInMaximumArea 54 .0694 .30874 .04201
Thus,itseemsthatpeoplewholiveinareaswhereresidentialparkingmaximumshavebeenimplementedprefertodrivelessandtoridebicyclesmore.Althoughtheseresidentsmayhaveself‐selectedtheirhousinglocation,asthenextsectionwilldescribe,peoplewholiveintheseareastendtodrivesingleoccupantvehicleslessfrequentlythantheircounterpartsinotherpartsofthecity.Thus,itislikelythatpoliciesaimedatreducingparkingrequirementsindenseareassuchasthosethathavealreadyadoptedparkingmaximumsinSanFrancisco,willmakesomeprogresstowardreachingtheirintendedgoalsofreducingthenumberoftripsmadebysingleoccupantvehicleandreducingcongestion.
Dopeopleself‐selecttoliveinplacesthatallowthemtotravelinacertainpreferredway?
Athird,relatedquestionarises.Asmentionedabove,thereissomeconcernthatsurveysarenotthemostprecisemethodforresearchingtravelbehaviorbecauseof
38
peoples’tendenciestochoosehousinglocationsthatallowthemtotravelacertainway.Forexample,thereisatheorythatpeoplewholiveinTODsmayself‐selecttodosobecausetheyarepre‐disposedtolivingwithoutacarorneartransit,andTODsmeetthesegoals.Thus,studiescontendingthatTODsencouragepeopletoaltertheirtravelbehaviorandgiveuptheircarsaresometimescriticizedforfailingtoaccountforthefactthatpeoplechoosetoliveintheTODsbecausetheyenablethemtolivetheirchosentravellifestyle–andarenotactuallythecauseofthebehavioritself.
Thus,aquestionwasincludedinthesurveythataskedrespondentswhytheychosetoliveinaspecificlocation.Thereasonsvariedagreatdeal,butthemajorityofrespondentsindicatedthattheychosetolivewheretheylivebecauseitisclosetoworkorschool(47),orforreasonsnotincludedinthesurvey.Respondentsweregiventheoptiontoindicateanotherreasonwhytheychosetheirresidence,andtheopen‐endedresponsesincluded:price,neighborhood,size,abilitytobike,andattributesofthehouse.Table12indicatesthechoiceslistedinthesurveyandpeoples’responsestotheclosed‐endedportionofthequestion.Althoughtheseresultsarenotstatisticallysignificant(Chi‐Squarepvalue=.106),theyarestilltellingbecausetheyindicatethatavailabilityoftransit,bicycling,orparking,werenotthepredominantreasonwhymostofthesurveyrespondentschosetheirhomes.
Table 12. Why People Chose Their Housing Location
Whypeoplechosetheirhousinglocation
Closetoworkorschool
Closetoretailandentertainment
Closetofriendsandfamily
Closetopublictransit
Availabilityofparking
Closetoscenic
locations/recreation
Noneofthe
above/other
NotMaxArea
25 10 9 12 5 14 25LivesinMaximumarea?
InMaxArea
22 10 3 9 0 3 10
Total 47 20 12 21 5 17 35
Conclusion
StudyFindingsInsummary,thisstudyfoundthat,overall,peoplewholiveinareaswhereparking
maximumshavebeenintroducedmakefewertripsinsingle‐occupantmotorvehiclesthanthosewholiveinareaswithoutparkingmaximumsandmoretripsbybicycleeachday.Peoplewholiveinareaswithmaximumsmakeanaverageof2.2tripsbysingleoccupantmotorvehicleeachday,comparedtothe.86tripsbymotorvehiclethatpeoplewholiveinparkingmaximumareasmake.Thosewholiveinareaswithparkingmaximumsreportedmaking1.8tripsbybicycleeachday,asopposedtothe.6tripsperdaythatpeoplewholiveoutsideofparkingmaximumareasreported.
Thestudyalsofoundarelationshipbetweenavailabilityofanoff‐streetresidentialparkingspaceandthechoiceofmodeforworkcommutesandentertainmenttrips.Also,peoplewithoutanoff‐streetresidentialparkingspaceavailableattheirhomereportedmaking,onaverage,1.4tripsbybicycleeachday.Thisiscomparedtothe.5tripsperdaythatpeoplewhohavemotorvehicleparkingathomereport.
Thesefindingssuggestthatavailabilityofaparkingspaceathomeislinkedwithmodechoiceandthatpeoplewholiveinareaswhereparkingmaximumshavebeenimplementeddo,indeed,exhibittravelbehaviorthatisdifferentthanthatofpeoplewholiveinareaswithoutparkingmaximums.Thus,itisverylikelythatpolicieslikeimplementingresidentialparkingmaximumsoreliminatingresidentialparkingminimumsinthedenseareasclosertodowntownarelikelytoencouragepeopletomakefewertripsbymotorvehiclebecausepeoplewholiveintheseareasarealreadyusingothermodesmoreoftenthansingleoccupantmotorvehicles.
LimitationsoftheStudy ThisstudywasconductedinaratherlimitedgeographicareawithinSanFrancisco.Thus,theresultsmightnotbegeneralizedtothepopulationofthecityasawholeortothepopulationsofothercities.Also,thesamplesizewasconstrainedtothosewhowerewillingtocompletethesurvey,totheareasthesurveyorswereabletoaccess,andtothosewhowereabletoaccessthesurveyonlineandfillitinaccurately.Thesamplesizeof182isalsorelativelysmall,consideringthepopulationofSanFranciscoasawholeismorethan800,000.Alargerandmorestratifiedsampleselectionmightbenecessarytoproducemorerobustresults.
PolicyImplicationsoftheResearchThefindingsofthisresearchsupplementandaugmentthelimitedliterature
regardingtheeffectsofreducedparkingrequirementsonpeoples’travelbehavior.ThisresearchyieldedresultsthatindicatethatpeoplewholiveinareasofSanFranciscothathaveadoptedparkingmaximumsdrivelessandridebicyclesmorethanresidentsofotherpartsofthecity.Thisresultsuggeststhatprogressiveparkingpoliciesthatlimittheamountofparkingthatcanbebuiltwithnewdevelopmentarelikelytomeettheirgoalsofencouragingpeopletodrivelessandtotaketransitorwalktotheirdestinationsmore
40
often.Theseresultsalsosuggestthatdensityandtheavailabilityoftransitinsuchareasdo,indeed,reduceresidents’needforavehicle. Also,theresultsdosuggestarelationshipbetweenavailabilityofaparkingspaceathomeandmodechoiceforworkandentertainmenttrips.Thus,bylimitingthenumberofparkingspacesthatdeveloperscanbuildinfutureresidentialprojectsinSanFrancisco,thecitycaninfluencethewaysinwhichpeopletravel.Itispossiblethatavailabilityofaparkingspaceathomeinfluencespeoples’decisionstodriveforworkandentertainmenttrips,and,thus,bynotmakingasmanyofthoseparkingspacesavailablewithnewdevelopments,peoplecanbeencouragedtodrivelessoften.
OpportunitiesforFutureResearch Thispaperpinpointsseveralopportunitiesforfutureresearchintotheinfluenceofparkingmaximumsandresidentialoff‐streetparkingontravelbehavior.First,detailedstudieswithtraveldiariesshouldbeadministeredinneighborhoodswhereparkingmaximumshavebeenadoptedandthosewhereparkingminimumsarestillonthebooks.Thedatacollectedfromsuchathoroughstudywouldhelpexpandthelimiteddatapresentedinthisstudyregardingthedifferencesintravelbehaviorbetweenpeoplewholiveinareaswithandwithoutparkingmaximums.Second,abefore‐and‐afterstudyshouldbeundertakentomeasure,forexample,neighborhoodtransitboardingratesbeforeandafterthedevelopmentofanewresidentialbuildingwithlimitedparkingavailabilityinanareaofSanFranciscowithparkingmaximums.Thisstudywouldservethepurposeofdeterminingwhetherlimitedparkingavailabilityreallydoesdrivepeopletoseekoutalternativemodesoftransportation.Finally,arandomstudylikethisoneshouldbeconductedoveralongerperiodwithalargersamplesizetogeneratemoreeasilygeneralizeddataaboutpeoples’travelpreferences.
AppendicesAppendix 1. Survey Instrument
Travel
1. Whichofthefollowingisyourprimarymodeoftravelforcommuting?Forthepurposesofthissurvey,pleaseconsider“primary”tomean“themodeyouuseforthelongestpartofyourtrip.”BicycleCityCarShare,Zipcar,orothercarshareservice Motorvehicle(singleoccupant)(car,truck,van,scooter,motorcycle)Motorvehicle(carpool)PublicTransit(Muni,BART,Caltrain,ACTransit,etc…) Walk WorkatHome/UnemployedOther____________________
2.
Pleaseindicatethenumberoftimesyouusedeachofthefollowingmodestogettoandfromworkonthedayofyourlastcommute.Forexample:ifyouwalked¼miletoMUNI,rodeMUNI,thenwalkedtoyouroffice,anddidthereverseforyourtriphome,thesewouldcountas4walkingtripsand2PublicTransittrips.________________Bicycle________________CityCarShare,Zipcar,orothercarshareservice________________MotorVehicle(singleoccupant)________________MotorVehicle(carpool)________________PublicTransit________________Walk________________WorkatHome/Unemployed________________Other
3. Howmanyminutesisyourtypicalone‐waycommutetowork?____________________
4.
Whichofthefollowingisyourprimarymodeoftravelforerrands,suchasgroceryshoppingordroppingoffdrycleaning?BicycleCityCarShare,Zipcar,orothercarshareservice Motorvehicle(singleoccupant)Motorvehicle(carpool)PublicTransit Walk Other____________________
5. Howmanytripsforerrandsdoyoutypicallytakeeachday?
Answercanbeafraction;Pleaseconsidereachstopmadeonthewaytoorfromanotherdestinationasaseparatetrip.____________________
6.
Whichofthefollowingisyourprimarymodeoftravelforentertainment,suchasgoingouttoarestaurantoramovie?BicycleCityCarShare,Zipcar,orothercarshareservice Motorvehicle(singleoccupant)Motorvehicle(carpool)PublicTransitWalk Other____________________
7. Howmanytripsforentertainmentdoyoutypicallytakeeachday?Answercanbeafraction;Pleaseconsidereachstopmadeonthewaytoorfromanotherdestinationasaseparatetrip.____________________
8.
Whatpercentageofyouroveralltraveltimeforalltripsdoyouspendoneachmode?________________Bicycle________________CityCarShare,Zipcar,orothercarshareservice________________MotorVehicle(singleoccupant)________________MotorVehicle(carpool)________________PublicTransit________________Walk________________Other100%Total
9. Travelpatternsareaffectedbywherepeoplechoosetolive.Itisimportantthatwegetatleastagenerallocationofyourhousehold.Whatstreetdoyouliveonandwhatistheclosestcrossstreet?_________________________and___________________________City:__________________________________________________
(Surveycontinuesonthereverse)
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10. Howmanyvehiclesareowned,leased,oravailableforregularusebythepeoplewhocurrentlyliveinyourhousehold?Householdmembersincludepeoplewhoconsideryourhometheirprimaryresidence,withwhomyoushareresourcessuchasincomeandvehicles.0123456ormore
Parking11. Howmanyoff‐streetparkingspaces,ifany,doyouhaveaccesstoatyourresidence?
Anoff‐streetparkingspaceisinagarageorlotonthesamepropertyasyourresidence,andnotonacitystreetorrentedoff‐site.0(Skipto#13)123456ormore
12.
Howdoyoupayforyouroff‐streetresidentialparkingspace?ItwasincludedintheresidencepurchasepriceormonthlyrentRentitfor$____________/monthPurchaseditfor$____________/monthOther____________(Skipto#15)
13. Ifyoudonothaveanoff‐streetresidentialparkingspaceavailableatyourresidence,wheredoyouparkyourmotorvehicle(s)ifyouownany?Rentaspaceelsewherefor$____________/monthParkonthestreetwithpermitParkonthestreetwithoutpermitOther_________________
14.
Fromwhereyoutypicallypark,howmanyminutesisthewalktoyourresidence?_________________minutes
Housing15. Whatisthemainreasonyouchosetoliveinthelocationofyourcurrentresidence?
ClosetoworkorschoolClosetoretailandentertainment ClosetofriendsandfamilyClosetopublictransportationAvailabilityofparkingClosetosceniclocationsand/orrecreation Noneoftheabove/Other____________
16. Doyourentorowntheresidenceyouarelivingin?RentOwnOther
17. Whichbestcategorizesyourresidence?SmallMulti‐unitcondoorapartmentbuilding(9unitsorless)LargeMulti‐unitcondoorapartmentbuilding(10unitsormore)Single‐familyhome Other
18.
Inwhicheradoyouestimateyourresidencewasbuilt?1954orearlier1955to19971998toPresentDon’tknow
AboutYou19.
Howmanyadultsage18orgreater,includingyourself,areinyourhousehold?1 2 3 4 5 6ormore
20.
Howmanychildrenunderage18areinyourhousehold?01 2 3 4 5 6ormore
21. Whatisyourgender?MaleFemaleSelf‐Identified
22.
Inwhatyearwereyouborn?_________________
23. Whatisyourannualhouseholdincome?$36,000orless $36,001to$75,000$75,001to$150,000$150,001orgreaterNoAnswer
Thankyouforyourhelp!
Survey#___________________Date___________________Location___________________
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