Parking Demand and Zoning Requirements for Suburban Multifamily Housing

Parking requirements for suburban multifamily housing should be based on solid data and clear policy logic. This paper reports on a comparison of three data sources for estimating residential parking demand: (a) overnight field counts, (b) household surveys of residents, and (c) household vehicle availability data drawn from the American Community Survey (ACS). The area of study is the Inland Empire subregion of Southern California. The parking demand implied by the ACS data is similar to field counts and household surveys. This similarity makes the ACS data a useful source of supplemental data for understanding local parking demand. The analysis confirms the positive relationship between household income and parking demand, and it supports rate structures based on the number of bedrooms in the unit. Comparison of field counts with ordinance requirements reveals that required parking exceeded demand by a modest degree for the projects studied, even when parking is free. Many policy choices are embedded in traditional requirements, such as the use of parking pricing, treatment of visitor parking, use of on-street parking resources, and rules on tandem parking. The paper proposes that local governments generate additional data on parking demand to calibrate their ordinance requirements better. A sequence of policy considerations is suggested for translating demand data to minimum parking requirements.