In this study of how off-street parking requirements affect urban form, we begin by analyzing the relationship between population density and streets in cities. We find that denser cities devote a greater share of their land to streets, but also have less street space per person. This relationship results in part from the difficulty of constructing new streets in built-out areas. The amount of street space does not increase as fast as population density, and this in turn helps explain why dense areas have less vehicle travel per person but higher levels of congestion. In contrast to streets, new off-street parking is supplied continually, owing largely to minimum parking requirements that make new development contingent on the provision of parking spaces. But the ample supply of off-street parking makes traffic congestion worse and inhibits street life. We recommend either removing off-street parking requirements, or converting them from minimums to maximums.
Michael Manville and Donald Shoup
1Dept. of Urban Planning, Univ. of California, Los Angeles, CA (USA)
Peter Midgley, gTKP
USA and Canada (USC)
United States of America