Automobile use and land consumption: Empirical evidence from 12 cities

Automobile use has increased significantly in most US cities for at least five decades. However, automobile infrastructure can consume significant amounts of land that could otherwise be used for non-transportation activities. Theory suggests that as automobile mode share increases in a city, the amount of land used for transportation also increases, whereas the land available for other uses decreases. This can result in a loss of activities from the city. This study compiles data from 12 cities in the United States to test these theoretical relationships. The findings suggest that on average each increase of 10 percentage points in the portion of commuters traveling by automobile is associated with an increase of more than 2500m(2) of parking per 1000 people and a decrease of 1700 people/km(2). In quantifying these relationships, this work provides a basis for assessing the potential impacts of transportation policy decisions on land use and on the concentration of people in cities. These issues ultimately have an impact on the vitality and financial viability of cities. URBAN DESIGN International (2012) 17, 221-227. doi:10.1057/udi.2012.12; published online 30 May 2012