Trip and Parking Generation at Transit-Oriented Development Reid Ewing, Guang Tian˟, Torrey Lyons, Preston Stinger, Rachel Weinberger, Ben Kaufman, and Kevin Shivley

˟ Department of City and Metropolitan Planning, University of Utah, guang.tian@utah.edu

Dense

Mixed use

Pedestrian friendly

Adjacent to transit

Built after

transit

Full developed

Self-contained parking

Redmond TOD, Seattle

Rhode Island Row, Washington D.C.

Fruitvale Village, San Francisco

Wilshire/Vermont, Los Angeles

Table 2. Average Mode Shares for TODs Studied

Table 3. Average Vehicle Trip Reductions Relative to ITE Rates

Table 4. Residential Parking Supplies as a Percentage of ITE, and Residential Peak Parking Demand as a Percentage of Actual Supplies

Table 5. Commercial/Mixed Use Parking Supplies as a Percentage of ITE, and Commercial/Mixed Use Peak Parking Demand as a Percentage of Actual Supplies

Table 6. Aggregate Parking Supplies as a Percentage of ITE Supplies, and Aggregate Peak Parking Demand as a Percentage of Actual Supplies

The decision of how best to allocate land around transit stations is a debated topic, with transit officials often opting for park-and-ride lots over active uses such as multifamily housing, office, and retail organized into transit-oriented developments (TODs). Providing large park-and-ride lots has been the default strategy to maximize transit ridership in the short run. But is it the best strategy in the long run? The debate continues when land is developed, with officials usually assuming that TODs require the same number of parking spaces as conventional development and that transit stations require the same number of park-and-ride spaces as non-TOD stations, even if much of the travel demand is non-auto and much of the transit demand is generated by TODs themselves.

In practice, guidelines for providing parking and mitigating vehicle trips come mainly from the Institute of Transportation Engineers (ITE) Trip Generation Manual and the ITE Parking Generation manual. However, both manuals have well-known shortcomings. Most importantly they focus exclusively on suburban locations with limited transit and pedestrian access, limiting the manuals’ recommendations to auto-dependent locations. Of course, TODs are designed to be the opposite of auto-dependent. Therefore, the goal of this study is to determine how many fewer vehicle trips are generated at TODs, and how much less parking is required at TODs, than ITE guidelines would suggest.

To answer these questions, we measure trip and parking generation at five TODs using a methodology that is the most robust published to date. As far as we can determine, this is the first study to estimate peak parking generation rates for mixed-use TODs. Also, this is only the second study to estimate vehicle trip generation rates for such developments. And it is one of the first to estimate mode shares for such developments.

Introduction

Englewood, Denver

Conclusion Mode Share

Walk mode shares fall within a fairly narrow band, from 16.6 % at Rhode Island Row to 28.3 % at Fruitvale. They mostly reflect the environment in which the TOD is located, and secondarily the number of commercial trip attractions contained within the TOD.

The smallest rail mode share is 13.6 % at Englewood. The largest shares are 27.2 % at Rhode Island Row and 26.1 % at Fruitvale;

Vehicle trip Generation

The number of vehicle trips at TODs range from one-third below to two-thirds below ITE rates.

The biggest reductions are at Rhode Island Row and Redmond. The smallest reduction is at Englewood. Even in a relatively auto-oriented TOD like Englewood, with an abundance of free parking, vehicle trip reductions are substantial relative to the suburban norm.

Parking Generation.

The supply of parking stalls for residential use at TODs ranges from 0.81 to 1.60 stalls per dwelling unit; the peak demand for parking ranges from 0.44 to 1.29 spaces per occupied dwelling ; the occupancy of residential parking spaces ranges from 54.3% to 80.6 %;

Actual parking supplies for commercial and mixed-use garages and lots in our TODs range from 22.6% to 61.2% of ITE supplies at Englewood;

At the overall peak hour, parked cars would fill only 19.0% to 45.8% of parking spaces if built to ITE standards and only 58.3% to 84.0% of parking spaces are filled.

Analysis We conducted a full count of all persons entering and exiting the buildings at each TODs and a brief intercept survey of a sample of individuals entering and exiting the building. Questions are like “How did you get here?” (e.g., by what mode of travel?), and “What is the purpose of your trip?” All the data were conducted from 7:30 a.m. to 9:00 p.m. on a workday in spring or fall 2015.

Parking demands for different land uses. The peak period for transit parking was daytime, while the peak periods for commercial and residential parking were evening and night. Given this fact, there is a real opportunity for sharing parking spaces among these different uses, something which is not realized at present.