On-site parking requirements may increase congestion

Michael Manville , Alex Beata & Donald Shoup, "Turning Housing Into Driving: Parking Requirements and Density in Los Angeles and New York," Housing Policy Debate 23 (2013): 2

The take-away: Regarding how the provision of parking has affected automobility in New York and Los Angeles, this article concludes that “increasing the supply of parking makes parking less expensive and encourages developers to bundle parking into the price of housing,” which “in turn makes owning a vehicle artificially cheap” and is therefore likely to increase congestion (373). Such an effect directly contradicts the goal of on-site parking requirements, and should thus cause local governments to reconsider their regulatory approach.

Abstract: This article examines the idea that residential minimum parking requirements are associated with lower housingand population densities and higher vehicle densities (residential vehicles per square mile). Cities frequently use minimum parking requirements to manage traffic, but parking requirements accommodate vehicles, suggesting they should lead to more driving and congestion rather than less. If parking requirements reduce congestion, they likely do so not by reducing the number of vehicles in an area but by reducing the densities of housing and people. We support this idea by comparing the Los Angeles and New York urbanized areas. We show that differences in housing, vehicle, and population densities across and within these urbanized areas are closely correlated with differences in the share of housing units that include parking, and that the share of housing units that include parking is in turn correlated with the stringency of parking requirements. Compared with LosAngeles, New York shifts less of the cost of driving into its housing market. We further show that within NewYork City, a 10% increase in minimum parking requirements is associated with a 5% increase in vehicles per square mile, a 4% increase in vehicles per person, and a 6% reduction in both population density and housingdensity. These relationships remain even after controlling for street layout and proximity to the subway.

Full article (requires access)