Limiting Parking Supply
Parking Maximums establish an upper limit on parking supply, either at the site level or across an area. Limits imposed by district or neighborhood are called “Parking Caps”. Either type of maximum can be imposed in addition to or instead of minimum parking requirements. Establishing a maximum allowable amount of parking can prevent developers from building excessively large lots, or limit the parking supply in an area based on roadway capacity or community priorities. Communities looking to increase tax revenue through redevelopment of parking lots, improve pedestrian safety and comfort downtown, or reduce stormwater runoff and heat island impacts of parking may want to consider parking maximums as a way to achieve those goals.
Either type of parking maximum can pose implementation issues, however. Setting a maximum leaves little room for error in projecting parking demand. Area-wide parking caps also leave little room for error and require substantial effort in planning and administration to determine the appropriate number of spaces and to allocate them to specific development projects. Furthermore, a restricted parking supply can present problems with spillover effects if not implemented carefully. Resident permit parking or other solutions to mitigate spillover effects and availability of other transportation options can improve the chances of success. Developers may also worry about the long-term marketability of the site if parking is restricted. If parking is restricted throughout an area, then the site will not be less competitive than surrounding sites. Restricting the parking supply may seem to put a community at a competitive disadvantage, and only makes sense in places where the benefits, such as rapid transit service, attractive pedestrian environments, or concentrations of businesses and services, outweigh any inconvenience from reduced parking.
To improve flexibility, planners can set up the parking maximums as transferable parking entitlements, so that the allowed number of parking spaces can be transferred or sold to another development if they are not needed. This allows for area-wide control of parking supply without restricting developments that need more parking. Developments requiring less parking can benefit by selling the rights to their additional spaces. 
- The Town of Burlington lists both maximum and minimum parking requirements for most uses throughout the town (see regulation).
- The City of Somerville provides parking maximums (in addition to minimums) for the Assembly Square Mixed Use District and the Planned Unit Development-A Overlay District that will go into effect when a new MBTA station is operational there (see regulation).
- The City of Cambridge has caps on the number of off-street parking spaces that may be provided within certain Special Districts and maximums for certain uses throughout the city.
- The Town of Belmont has maximum numbers of parking spaces allowed for each subdistrict of the McLean Hospital property and in the Belmont Uplands District (without parking minimums) (see regulation).
- The Town of Bedford has maximum parking allowances for certain uses throughout the town (see regulation).
- “In 1977, the City of Boston adopted a freeze on commercial parking open to the public, but not parking reserved for individuals or a company use within office buildings. While the number of commercial spaces have not increased, there was a 26% increase in exempt spaces between 1984 and 1987 alone and motor vehicle traffic increased dramatically along major corridors to the city.” 
- “In 1975, the City of Portland set an overall cap of approximately 40,000 parking spaces downtown, including existing and new parking facilities. The cap was increased to about 44,000 spaces by the 1980’s and increased again in the 1990’s. The City is generally satisfied with its parking policies and believes it has helped increase transit use from 20-25% in the early 1970’s to 48% in the mid-1990’s.”  In addition, Portland sets maximum parking limits based on type of use and availability and frequency of transit service, and allows transfer of unused parking entitlements. 
- San Francisco limits parking downtown to 7% of the building’s floor area. 
- Seattle allows a maximum of one parking space per 1,000 square feet of office space downtown, and is considering extending this limit to areas outside of downtown as well. 
- Redmond, Washington, a suburban community, allows a minimum of 4 and a maximum of 5 spaces per 1,000 square feet of floor area for most uses in the Neighborhood, Retail, and General commercial zones. 
- Helena, Montana establishes maximum parking ratios as a percent above the minimum parking ratio (e.g. no more than 110% of the minimum for parking lots of more than 51 spaces). 
- U.S. Environmental Protection Agency, Parking Spaces / Community Places: Finding the Balance Through Smart Growth Solutions, January 2006; p. 16-18. Available as a free download at http://www.epa.gov/smartgrowth/parking.htm, or click here for the PDF.
- Maryland Governor’s Office of Smart Growth, Driving Urban Environments: Smart Growth Parking Best Practices, March 2006; p. 5-6. Available as a download.
- Jason Wittenberg, “Parking Standards in the Zoning Code“, Zoning News, January 2003, p.3.
- Victoria Transport Policy Institute, “Parking Maximums”, Online TDM Encyclopedia: http://www.vtpi.org/tdm/tdm28.htm#_Toc128220478.
- Todd Litman, Parking Management: Strategies, Evaluation, and Planning, Victoria Transport Policy Institute, April 2006; p. 15. Available as a free download from http://www.vtpi.org/park_man.pdf or by clicking here.
- Fitzgerald & Halliday, Inc., Northwest Connecticut Parking Study – Phase II: Model Zoning Regulations for Parking for Northwestern Connecticut, Northwestern Connecticut Council of Governments and Litchfield Hills Council of Elected Officials, September 2003. Available as a free download from http://www.fhiplan.com/PDF/NW%20Parking%20Study/NW%20Connecticut%20Parki… or by clicking here.
- Christopher V. Forinash, et al., “Smart Growth Alternatives to Minimum Parking Requirements“, Proceedings from the 2nd Urban Street Symposium, July 28-30, 2003. Available as a free download from http://www.urbanstreet.info/ or click here for the PDF.