Trip Generation, Parking Generation and Transit-Oriented Development
Arlie AdkinsUC Berkeley
Metro TDM SymposiumLos Angeles
February 5, 2008
Outline
• Trip Generation
• What we already know
• New evidence
• Parking Generation
• New evidence
• Minimum parking requirements
• Preliminary results from nationwide survey
• Lessons
TOD and Travel BehaviorWhat We Already Know
TOD and Travel BehaviorWhat We Already Know
Source: Lund, Cervero, Wilson (2004)
TOD and Travel BehaviorWhat We Already Know
Source: Renne (2005)
Comparison of Shares of Transit Commuting Comparison of Shares of Transit Commuting in TODs versus Regions from 1970 in TODs versus Regions from 1970 -- 20002000
TODs maintained market shares while MSAswitnessed sharp declines
TOD and Travel BehaviorWhat We Already Know
35% higher probability
Sensitivity Test: Car Ownership Covariate
Source: Lund, Cervero, Wilson (2004)
TOD and Travel Behavior ITE Trip and Parking Generation
• Called the “Bible” of traffic Impact analysis • Widely relied on, especially in smaller cities• Known suburban, car- oriented bias • Likely overstates auto traffic impacts of TODs
TOD and Travel BehaviorPutting the Issue in Context
Hypothetical 8 Acre Site
• 162 more units
• 20% density bonus
• $12 million saved in parking costs
• Increased transit ridership
• 801 units
• 100 units per acre
• 1762 parking spaces
• $33.3 million in parking capital costs
2.2
Park
ing
Spac
es p
er U
nit
• 963 units
• 120 units per acre
• 1058 parking spaces
• $21.3 million in parking capital costs
1.1
Park
ing
Spac
e pe
r Uni
t
Source: TCRP Report 128
TOD and Trip Generation New Evidence: TCRP Report 128
• Gauges TOD trip generation over-estimation
• Inform ITE Trip Generation Manual with adjustments for transit proximity
• Results presented in similar format to ITE
• 17 sites across 4 regions
TOD and Trip Generation New Evidence: TCRP Report 128
TODVeh. Trips
per DU (24 hr.)
ITE Rate
(24 hr.)
% point differencefrom ITE
Rate
Center Com. 4.79 6.72 -28.7%
Collins Cir. 0.88 6.72 -86.9%
Gresham Cen. 5.91 6.72 -12.1%
Merrick Apts. 2.01 6.72 -70.2%
Quatama Cr. 6.34 6.72 -5.6%
Mean 3.99 -- -40.7%
Std. Dev. 2.42 -- 36.1%
Metro Portland Trip Generation
TOD and Trip GenerationNew Evidence: TCRP Report 128
TODVeh.
Trips per DU
(24 hr.)
ITE Rate
(24 hr.)
% point differencefrom ITE
Rate
Mission Wells 3.21 6.72 -52.2%Montelena 2.46 6.72 -63.4%
Park Regency 5.01 6.72 -25.4%Verandas 3.10 6.72 -53.8%
Wayside Com. 3.26 5.86 -44.3%Mean 3.41 -- -47.8%
Std. Dev. 0.95 -- 14.3%
•24 Hours: 44% fewer trips
•AM Peak: 49% fewer trips
•PM Peak: 48% fewer trips
TOD and Trip GenerationNew Evidence: TCRP Report 128
TOD and Trip GenerationNew Evidence: TCRP Report 128
Scatterplot of PM Trip Generation Rate to ITE Rate with Residential Densities
TOD and Trip GenerationNew Evidence: TCRP Report 128
Scatterplot of PM Trip Generation Rate to ITE Rate with Distance to CBD
20 units/acre
5 units/acre
Influence of Residential Densities & Distance to CBD
TOD and Trip GenerationNew Evidence: TCRP Report 128
TOD and Travel BehaviorParking Generation
But What About Parking?
Parking, Trip Generation and TODParking Generation: New Evidence
• Empirical study of parking generation
• 31 sites in Bay Area and Portland
• Peak and off-peak counts at each site
• Multiple sites in some station areas capture wide variation
TOD and Travel BehaviorParking Generation: New Evidence
SiteObserved Parking
Generation
Differencefrom ITE
Rate
Gateway Station
Gateway Terrace 0.53 -56%
Gateway Park Apts. 0.82 -32%
E 148th Ave Station
Rachel Anne 0.88 -26%
Dalton Park 1.17 -3%
E 162nd Ave StationSequoia Park 0.79 -34%
Morgan Place 0.65 -46%
Gresham Central Station
Gresham Central 1.00 -17%
Mean 1.08 -11%Standard Deviation 0.24 20%
Site Observed Parking
Generation
Difference from ITE
Rate
Beaverton Creek Station
Center Pointe 1.23 3%
Elmonica Station
Elmonica Court 0.90 -25%
Cambridge Crssng. 1.05 -13%
Willow Creek
Wyndhaven 0.90 -25%
Quatama Station
Briarcreek 1.12 -7%
Quatama Crossing 1.32 10%
Quatama Village 1.37 14%
Orenco Station
Orenco Gardens 0.76 -37%
Portland Parking Generation: Preliminary Results
TOD and Travel BehaviorParking Generation: New Evidence
Site Observed Parking Generation % different from ITE Rate
Walnut Creek: Pleasant Hill BART Station
Diablo Oaks 0.74 -38%
Arch. Walnut Creek 0.92 -23%
Park Regency 1.06 -12%
Arch. Walnut Creek Stat. 1.09 -9%
Villa Montanaro 1.23 -3%
Iron Horse Park 1.48 23%
San Leandro: Bayfair BART StationThe Hamlet 1.07 -11%
Union City BART StationThe Verandas 1.11 -7%
Parkside 1.13 -6%
Fremont BART StationPresidio 1.23 -3%
Watermark Place 1.27 5%
Mission Peaks 1.35 12%
Archstone Fremont 1.45 21%
Sun Pointe Village 1.47 23%
Park Vista Apartments 1.48 24%
Alborada Apartments 1.69 41%
Mean 1.22 2%Standard Deviation 0.24 20%
Bay Area Parking Generation:Preliminary Results
TOD and Travel BehaviorParking Generation: New Evidence
FremontBART
TOD and Travel BehaviorParking Generation: New Evidence
• Preliminary results show that peak parking generation increases by about .38 each half mile walking distance from the station
Given this number:
• A hypothetical 400-unit apartment complex built immediately adjacent to a rail station would need about 328 spaces
• A 400-unit complex 1 mile from the station would need 632 spaces
That’s a potential savings of as much as 3 acres!
Preliminary Results
TOD and Travel BehaviorParking Generation: New Evidence
• Very few sites in study would support a car free lifestyle
• People might commute to work by train, other trips still require a car
• Further analysis may shed light on this
• Clearly car storage occurring
ITE Overestimates
Preliminary Results
TOD and Travel BehaviorParking Generation: New Evidence
Sensitivity Test: Car Ownership Covariate
TOD and Travel BehaviorParking Generation: Lessons
A Natural Marriage: TOD & Carsharing?A Natural Marriage: TOD & Carsharing?
Work/School
Shopping
Pers. BusinessMedical
Social-Rec
Other
Trip Purposes• 30% car-shedding (2001-2005)
• Mean VMT Reduction of 12% (2001-2005)
• Unfortunately carshare vehicles rare in suburban station areas
R. Cervero, A. Golub & B. Nee,(2007) San Francisco City CarShare: Longer-Term Travel-Demand Trends and Car Ownership Impacts, Transp. Res. Rec. 1992,, pp. 70-80.
• Nationwide Survey of every city with a rail transit station
• 35% response rate (40% of cities over 100,000)
• Concentrations of 10 or more responses in Los Angeles, Bay Area, Chicago, and Washington-Boston corridor
TOD and Travel BehaviorMinimum Parking Requirements
• Allowable Grounds for Variances to Minimum Parking Requi
TOD and Travel BehaviorMinimum Parking Requirements
Key findings:
•96% of cities surveyed have minimum off street parking requirements for multi-family housing
• 86% percent of these cities allow for variances to these requirements
•Average maximum variance allowed for rail station proximity: 24%
Preliminary Results
• How receptive do you think elected officials in your city would be to lowering minimum parking requirements?
•
TOD and Travel BehaviorMinimum Parking Requirements
In GeneralWithin Walk of
Rail Station
Preliminary Results
• Walkable, bikable neighborhoods
• Nearby services - including grocery stores and high quality school
• Access to a true transit network
• Carshare
TOD and Travel BehaviorLessons: Think Holistically
Train Station + Housing ≠ TOD
• However...
TOD and Travel BehaviorLessons: Focus on Improving People’s Lives
• Global climate change is a strong policy and political driver
• Voters are paying attention
Photos credit: Flickr user Atwater Village Newbie
Photos credit: California High Speed Rail
TOD and Travel BehaviorLessons: Focus on Improving People’s Lives
... a word of caution
• Efforts to reconfigure our transportation systems and our cities must be rooted in improving people’s lives if they are to be politically sustained
• Historically, this has been the root of major urban transformations (e.g. post-war suburbanization)
• Makes our jobs easier and more rewardingPhotos credit: Flickr user Atwater Village Newbie
Photos credit: California High Speed Rail
•Conventional high frequency bus routes often overlooked in TOD discussion
• Bus lines generally carry the bulk of transit riders in a region
•More research is needed on the relationship between bus and TOD
TOD and Travel BehaviorLessons: Bus Networks and TOD
Los Angeles Bay Area Portland
Source: LA Metro; MTC; TriMet
TOD and Travel BehaviorLessons: Bus Networks and TOD
Metro Rapid(Los Angeles)
Frequent Service (Portland)
TOD and Travel BehaviorLessons: Bus Networks and TOD
Examples of recent bus TOD in Portland
Photos credited to developers
TOD and Travel BehaviorThank You!
• Thank you! And keep up the good work.
• Please let me know if you’re interested
• in seeing our final parking generation analysis
• or results from the parking survey.
• Arlie Adkins
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