A November 2020 article in Transportation Research Record addresses questions on parking supply and demand at transit-oriented developments (TODs) through comparative case studies of seven TODs in the U.S.A. 

"Comparative Case Studies of Parking Reduction at Transit-Oriented Developments in the U.S.A." was authored by Reid Ewing, Keuntae Kim and Sadegh Sabouri of the University of Utah, with Fariba Siddiq of UCLA and Rachel Weinberger of Weinberger & Associates.

As far as the authors can determine, this is one of the first studies to estimate peak parking generation rates for TODs. Developments are often characterized in relation to “D” variables—development density, land use diversity, urban design, destination accessibility and distance to transit. The seven TODs studied in this project are exemplary when it comes to the Ds.

At the overall peak hour, just 51.2%–84.0% of parking spaces are filled. Because of limited use of shared parking, even these exemplary developments do not achieve their full potential. At the overall peak hour, parked cars would fill just 19.5%–69.4% of parking spaces if the developments were built to Institute of Transportation Engineers (ITE) standards.

With one exception, peak parking demand is less than 60% of the parking supply guideline in the ITE Parking Generation manual. A sixth D, demand management (parking management), is mixed at the TODs studied. For one thing, there is a dearth of shared parking, though opportunities abound. Another area in which parking policies are not always smart is in bundled residential parking. At some TODs, a parking space/permit comes with each apartment whether the renters want it and use it or not. Such parking is effectively free. A third area in which parking policies are not always smart is in free commercial parking, the counterpart of bundled residential parking.

The paper draws on findings from the NITC project "Reducing VMT, Encouraging Walk Trips, and Facilitating Efficient Trip Chains through Polycentric Development."

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The National Institute for Transportation and Communities (NITC) is one of seven U.S. Department of Transportation national university transportation centers. NITC is a program of the Transportation Research and Education Center (TREC) at Portland State University. This PSU-led research partnership also includes the Oregon Institute of Technology, University of Arizona, University of Oregon, University of Texas at Arlington and University of Utah. We pursue our theme — improving mobility of people and goods to build strong communities — through research, education and technology transfer.