Author(s)

M. Salatino

Abstract

Interaction between urban form and transportation costs has been a much debated issue during the past decades. Density influences travel behaviour, since individuals must travel farther when land use patterns become more dispersed. This study tries to assess density effects on transportation in terms of money, by calculating additional costs of travel due to decreasing residential density. First, a linear model was implemented in order to foretell urban density. Then we turn these densities in travel demand by means of a relationship between density and transportation variables. Finally, we convert travel demand into internal and external costs. The model was tested in a small urban area in Southern Italy. A comparison of total commuting costs was made by comparing the actual situation with two possible future scenarios. As is to be expected, laying down new roads in peripheral areas should increase travel demand and transportation costs, as a consequence of decreasing densities. Keywords: urban sprawl, density, driving costs, sustainable mobility. 1 Introduction Automobile dependency is the main obstacle to implement a sustainable transportation system. In particular, reliance on the car is expensive, since it implies higher costs for commuting. To give an example, McCann [1] observed that households in automobile dependent communities devote higher shares of expenditures to surface transportation than those in communities with more transportation modes. At a regional scale, an international comparison by Newman and Kenworthy [2] also found higher per capita transportation expenditures in more automobile-dependent cities.

Keywords

urban sprawl, density, driving costs, sustainable mobility.