UrbanismandParkingDemandinNewEnglandCities

WesMarshallNormanGarrick

ABSTRACT

InthispaperwelookattheinfluenceofspecificurbandesignfactorsonparkingdemandinthreetraditionalandthreecontemporaryNewEnglandcommercialcenters.Wefoundthatthecharacterandstructureofthecentersintermsofbuildingdensity,streetandsidewalkdesign,andthemanagementandorganizationofparkingaswellasthepopulationdensitiesandstreetstructureofthesurroundingneighborhoodsresultinverydifferenttransportationoutcomes.Nearly25%oftheusersatthetraditionaldowntownstravelbymeansotherthantheautomobilecomparedtoonly9%atthecontemporarysites.Additionally,70%ofthoseatthetraditionalsitesalwaysparkonceandwalktomultipleerrandswhileonly25%ofthepeopleatthecontemporaryplacesdidso.Thesedifferencesresultedintraditionalcentersthatweremuchmorevibrantthattheircontemporarycounterparts;infact,thetraditionalcentershad250morepedestriansontheirstreetsatanyonetimeandatotalof1,300more

peoplewith400fewerautomobilesparkedonsite.

1.INTRODUCTION

In this paperwe examine howurbandesign factors affect parking demand in six smallNewEnglandcommercialcenters.Threeofthesecenters,Brattleboro,VT,Northampton,MAandWestHartford,CT,aretraditionalNewEnglanddowntownswithmixedlandusessupportedbyanorganizedsystemofparking. Theother three,AvonCenter,CT,GlastonburyCenter,CTandSomersetSquareinGlastonbury,CT,aremorecontemporary,automobile‐orientedsitesthatareofsimilarsizetothetraditionalcenters. Thespecificurbandesignfactorsthatwerecomparedincluded

• Thecharacterandstructureofthecentersintermsofbuildingdensity,streetandsidewalkdesign,andthemanagementandorganizationofparking,• Theneighborhoodsandstreetnetworkofthesurroundingresidentialareasintermsofpopulationdensitiesandstreetstructure.

We collected data to characterize the supply,management and usage of parking,modechoice for travel to the centers, and level of pedestrian activities for each site. Finally, weconductedon‐sitesurveystocharacterizehowusersperceiveandusethesites.Thisdatahelpedassess whether or not there are systematic differences in parking demand between thetraditionalandcontemporarycenters.

2.BACKGROUND

Fordecades,wehaveallowedminimumparkingrequirementstoshapehowwebuildoururbancenterseventhoughweknowthaturbancharactershouldbethecontrollingfactor.InhisrecentbooktitledParkingManagementBestPractices,Litmanexplainshowurbandesignfactorsmight affect parking demand (1). He rationalizes that better urbanity and improved walkingconditionshelpincreasethefunctionalparkingsupplybyextendingtheeffectofsharedparking.In fact,hesuggestsreducingparkingrequirementsby5 to15%inmorewalkableareaswherepeoplehavetheabilitytoparkonceandwalktomultipleerrands.Theproblemisthatveryfewifanystudiesquantifytheseconcepts.

Mostparkingordinancesarebasedonthosefromnearbytownsorreferencebookssuchas the ITEParking Generationmanual.While the introduction toParking Generationmentionsthatlandusedensity,pedestrian‐friendlydesign,andmulti‐stoptripmakinghavethepotentialtoinfluenceparkingdemand,ITEmakesnoattempttoquantifyorevengiveinformalinstructionsashowtoaccountforsuchfactors.Andalthoughthelatesteditionofthemanualisbeginningtocategorize parking demand for single land uses into one of five area types (rural, suburban,suburbancenter,centralcity,andcentralbusinessdistrict),theITEapproachcontinuestofocusongatheringmoredata(2). Thebiggerissueisthatevenwithmoredatapoints,thisapproachstillfailstotrulyconsidertheeffectofurbandesignonparkingdemand.

Knowledgeof therelationshipbetweenurbanismandparkingdemandhasbeenaroundfarlongerthantheregulationsthemselves.Infact,theHighwayResearchBoard’s1971bookontheprinciplesofparkingsupportsmostofLitman’sideasabouthowurbandesignaffectsparkingdemand. Repeatedly ignoring the intricacies of this connection has pushed us into thepredicamentwherewecontinuetoallowparkingtocontroltheurbanform.Ourgoalistoresetthis balance by conducting research that investigates the extent to which urban design isimportantinparkingdemandforthesixNewEnglandcenterswestudied.

3.CHARACTER&STRUCTUREOFTHECENTERS

Wecomparedtheurbancharacterofthetraditionalandcontemporarycentersbylookingfordifferencesincharacterandstructureintermsoflandusedensity,howtheparkinglotsaremanagedandorganized, and in thedesignof the streets and sidewalks. Thesedifferences aresummarizedinthefollowingsections.

3.1DensityWithintheTownCentersThere were distinct differences in both land use densities and floor area ratios (FAR)

between the traditional and contemporary sites. The traditional sites achieved higher densityandprovidedmoreusablebuilding space. Table1 shows that thebuildingdensitywasnearly58%higherforthetraditionalsitesandtheFARwas176%greater.Thesehigherdensitiesatthetraditionalsitesresultedinover90%moreleasablebuildingspace.

Table 1 Characteristics of the Contemporary & Traditional Sites 3.2 Management &OrganizationofParking

CONTEMPORARY SITE

AVERAGE

TRADITIONAL SITE AVERAGE

DIFFERENCE

TOWN CENTER COMPARISON

TotalDowntownLandArea

2,573,432SF

2,010,601SF

‐21.9%

TotalBuildingFootprint 392,065SF

492,239SF

25.6%

TotalBuildingSpace 460,598SF

869,487SF

88.8%

BuildingDensity 0.16 0.25 57.9%

FloorAreaRatio 0.17 0.47 175.7%

PedestrianLevelofService

3.09=C

2.38=B

‐23.0%

WALKABLE ZONE COMPARISON

WalkableZonePopulation 2,049 8,328 306.5

%

WalkableZoneArea(sq.mi.) 2.6 2.2

‐15.1%

WalkableZoneDensity(pop./sq.mi.) 802.7 3764.5 369.0

%

TotalLengthofHighways(mi.) 1.36 0.63

‐53.9%

TotalLengthofMajorRoads(mi.) 1.61 3.06 90.7

%TotalLengthofMinorRoads(mi.) 11.11 19.75 77.8

%MinorRoadDensity(streetmiles/sq.mi.) 88.22 164.23 86.2

%

Minor‐MajorRoadRatio 4.14 11.07 167.6%

TotalNo.ofIntersection 103.50 218.67 111.3%

IntersectionDensity(intersections/sq.mi.) 806.98 1847.9

6129.0%

TotalNo.ofDeadEnds 19.50 25.33 29.9%

Dead‐EndDensity(deadends/sq.mi.) 151.17 211.71 40.1

%Intersection‐DeadEndRatio

5.32 16.04 201.5%

TOWN COMPARISON TownPopulation 26,528 34,857 31.4

The traditional sites supplied a broad range of parking optionswith on‐street parking,privateandmunicipaloff‐streetsurfaceparking,andaparkinggarageateachsite.Parkingatthecontemporarysiteswaspredominantlyprivately‐owned,off‐street,surfacelots.Figure1depictstheseparkinglottypesforonetraditionalandonecontemporarysite.Municipalspacesmakeupmorethanhalfoftheparkingatthetraditionalcenters.Intermsoflayout,thesurfacelotsatthecontemporary sites surround and separate buildings. Conversely, the surface parking at

traditionalsitesisoftenlocatedatmid‐block.

Figure1Traditional&ContemporarySiteParkingLotTypesComparison

Figure2illustratesparkinglottypesandpeakoccupancycountsfortwotraditionalsites.Overall,municipalparkingexperiencesthegreatestdemand.Atapeakoccupancy,theseshared,

oftencentralized,spaceswereover90%fullwhiletheprivatespaceswerelessthan60%full.

Figure2ParkingLotsTypes&DemandforTraditionalSites3.3Street&SidewalkDesignFigure3Traditional&ContemporarySiteStreet&SidewalkComparison

Traditional SiteContemporarySite Street&SidewalkStreet

&Sidewalk

Figure 3 depicts the disparities between the typical streets and sidewalks through thetraditional and contemporary sites. The pedestrian environments were very different eventhougheverysitefeaturedhighintensityautomobiletraffic. Inmanycases, thestreetsshapingthe contemporary sites servedas significantpedestrianobstacles. With regard to consistency,thesidewalksatthetraditionalsitesweretypicallywidewithhighconnectivitythroughouttheentirecenter.Alternatively,thecontemporarysitesprovidedwide,landscapedwalkwayswithinindividual plazas but rarely were the sidewalks continuous between plazas. Figure 4 showssometypicaltraditionalsitepedestrianconnectionsfromamid‐blockparkinglot.

Themajorstreetsateachofthetraditionalsitereceivedalevelofservice(LOS)Bbased

uponthepopularLandismodelwhiletwocontemporarysitesreceivedLOSCandthethirdLOSDas shown inTable 1. These values indicate that the traditional sites providepedestrianswithsaferandmorecomfortablesurroundings,resultsfurtherconfirmedbytheusersurveythatwediscusslaterinthispaper(3).

4.THEWALKABLEZONE

Another set of factors potentially influencing parking demand is the makeup of thesurrounding residential zones (especially the areas within a reasonable half‐mile walkingdistance)and theextent towhich theyareconnected to thecommercial centers (4). Thehalf‐milezonewasadjustedtoexcludeareasbeyondmajorpedestrianobstructionssuchashighwaysorrivers.

Figure5WalkableZoneStreetStructureComparison

4.1DensityAroundtheTownCentersOverall,Table1showsthatthe1/2‐milewalkablezonessurroundingallthetowncenters

were denser in population when compared to the rest of the town. However, while thecontemporarysiteswereonly27%denser, the traditional townswereover180%denser thantherestoftheirrespectivetowns.Secondly,thetraditionalwalkablezoneswere369%denserinpopulation than the contemporary site walkable zones. This was the case even though thetraditionaltownsthemselveswereonlyslightlymorethantwiceasdense. Consequently,morethan 6,200 additional people lived within walking distance of each of the traditional towncenters.

4.2StreetStructureTable 1 also quantifies the walking environment based upon the surrounding road

networks shown in Figure5. The traditional sites averaged an86%densernetworkofminorroads and almost double the total length of roads suitable for a pedestrian. In terms of theoverall street network, the traditional sites had 111%more intersections and a 129% higherintersection density. The appreciably higher intersection density typically correlates to moredirectpedestrianroutes(5).

5.TRANSPORTATIONRESULTSRELEVANTTOPARKINGDEMAND

The differences in the character and structure of the sites and surroundingneighborhoods correspondedwith very different transportation results. The objective in thissection is todetermine the transportation choicesof theusersof these centers andhow thesedecisionsimpactparkingdemand.Whenassessingthetransportationoutcomes,weneedtobearinmind that urban design factors are interrelated; each feature is part of a total package thathelpsfacilitatethefunctionalityofthetraditionalsites.

5.1AlternativeModesWhile only 9% of those surveyed traveled to the contemporary sites via amode other

than the automobile, this number reached 25% for the traditional sites. Other than driving,walkingwasthemost importantmode ineachof thesetowncenters. Ourusersurveyshowedthatatthetraditionalsites,almost15%oftripstothetowncenterwerewalkingtripswhileatthecontemporarysites,only7%walkedtothesite.Bikeusereached2.5%intheusersurveyatthetraditionalsitescomparedtoanegligiblebicycleuseatthecontemporarysites. Intermsofpublic transportation,nearly7%of thoseat the traditionalsitesused transitcomparedtoonly1.4%atthecontemporarysites.Thedifferencewasnoteworthybecauseboththecontemporaryandtraditionalsiteshadsimilarlevelsoftransitavailable(6).

We also compared the survey results to the U.S. average found in the 2001 NationalHouseholdTravelSurvey(NHTS)(7).Theusersofthetraditionalsiteswalkedmorethantwicethenational average, usedpublic transitmore than four times thenational average, andbikedmore than eight times the national average. With an extra 15% of people reaching the towncenters bymeans other than a car, this equates to 300 unused parking spaces in the average2,000‐speace center. Our research found that off‐street surface parking averaged 525 SF perspace(includingaccesslanesandparkinglotislands);baseduponthisnumber,300unnecessaryparkingspacescouldresultinover3.6acresoflandnolongerneededforparking.

Table2TransportationResultsRelevanttoParkingDemand

CONTEMPORARY SITE AVERAGE

TRADITIONAL SITE AVERAGE

DIFFERENCE

MULTI-STOP TRIP MAKING

AlwaysParkOnce&WalkSometimesParkOnce&WalkNeverParkOnce&Walk

25%43%32%

70%23%7%

180.0%‐46.5%‐78.1%

MODE CHOICE: U.S AVG. FOR SHOPPING TRIPS (2001 NHTS)

DrivingPublicTransitBicyclingWalking

91.5%1.4%0.3%6.5%

MODE CHOICE: USER SURVEY

DrivingPublicTransitBicyclingWalking

91.0%1.4%0.2%7.4%

75.2%6.9%2.5%14.8%

‐17.4%392.9%1150.0%100.0%

MODE CHOICE: 2000 CENSUS WORK TRIPS BY TOWN

DrivingPublicTransitBicyclingWalking

92.1%1.1%0.4%0.7%

83.4%2.3%1.6%8.3%

‐9.4%109.1%300.0

5.2Multi­TaskTripMaking.Whenaskedwhethertheyalways,sometimes,orneverparkonceandwalkedtomultiple

errands, over 70% of traditional site users said always compared to only 25% at the morecontemporarysites. Furthermore,whileonly7%of thoseat the traditional sitesneverparkedonce andwalked, this number exceeded32%at themore contemporary sites. Table 2 showstheseresults.

Withregardtoparkingdemand,thisdistinctionisnoteworthy.Parkingonceandrunningmultiple errandswithin a downtown as opposed to driving from store to store results in lessparking being required to accommodate the same activity; this is a more efficient use ofresources. Litman suggested reducing parking requirements by 5 to 15% in more walkablecommunitieswhere parking once and runningmultiple errands is favored. If only 25% of theusersinanaveragetowncenterofapproximately2,000spacesparkedonceandwalkedtojusttwo destinations, this would result in 500 fewer parking spaces used. Based upon our landconsumptioncalculations,thiswouldsaveanothersixacresofsurfaceparking.Withourresultssuggesting that 70% of users at the traditional sites always park once and walk to multipledestinations,thepotentialforincreasedefficiencyinparkingisfargreater.

5.3Parking&On­SiteActivityThe traditional sites provided less parking, used less parking relative to the land use

types,andusedwhatparkingtheyhadmoreefficiently(6). Figure6showsthatthetraditionalsites provide half the amount of parking of the contemporary sites even though the standard

regulationsforboththetraditionalandcontemporarytownsrequiresimilarlevelsofparking.

Figure6ParkingRequired,Provided,andUsed

In termsof on‐site activity, the traditional sites averagedover300pedestrians and thecontemporary sites less than fifty as well as twice the number of people in stores on similarweekdayafternoons. Combinedwithanestimateoftheon‐siteemployees, thetraditionalsitesaveraged 1,300more people on site; a level of activity successfully sustainedwith 400 fewerparkedcars.

6.CONCLUSIONS

Our research illustrates how urban design factors influence parking demand. Thecharacterandstructureofthetraditionalcentersintermsofhigherdensities,sharedmid‐blockmunicipal parking lots, and a better pedestrian environment help impact parking demand byincreasing the opportunities and instanceswhere town center users could park once and runmultipleerrands. These improvingconditions thatare favorable tomulti‐task tripmakingcanreduceparkingrequirementsbymorethan25%.

Theplacesthatareabletoprovidesignificantlylessparkingwithrespecttothenumberofpeopleonsitewereabletodosonotonlybecauseofthecharacterandstructureofthecentersthemselves,butalsothatofthesurroundingwalkablezone.Acentercaneffectivelyoperatewithlessparking in situationswhere theopportunity to travel viamodeother than the automobileexists.The traditional sites inourstudypossessedahigherdensityof residentialdevelopmentand amuch denser network ofminor roads. Such palpable differences resulted in over 15%more trips to the traditional centers by way of a mode other than the automobile andconsequentlyfarlessparkingdemand.

At first glance, it might be surprising that these traditional town centers were able toattract1,300morepeoplewith400fewercarsonsiteonanaverageday. Betterurbandesignnot only makes this possible but also gives these traditional centers the opportunity tosuccessfully provide less than half the amount of parking typically considered for such adevelopment. Inturn, thesesamecentersavoidneedlesslydedicatingacresof landtoparking;landthatwouldbetterservethesedowntownsinanotherfashion.

7.REFERENCES

1 LitmanT:ParkingManagementBestPractices.PlannersPress,20062 InstituteofTransportationEngineers:ParkingGeneration,3rdEdition.Washington,D.C.,20043 LandisB,VattikutiV,OttenbergR,McLeodD,GuttenplanM:ModelingtheRoadsideWalkingEnvironment:APedestrianLevelofService.TransportationResearchBoardAnnualMeetingCD‐ROM20014 LitmanT:ParkingManagement:Strategies,EvaluationandPlanning,VictoriaTransportPolicyInstitute,20065 MarshallS:Streets&Patterns.NewYork,SponPress,20056 MarshallW,GarrickN:ParkingatMixed‐UseCentersinSmallCities.TransportationResearchRecord20067 BureauofTransportationStatistics:NationalHouseholdTravelSurvey,2001