The Influence of Urban Transportation and Land Use Policies on the Built Environment and Travel Behavior

For decades, policymakers in many American cities have called for measures to bolster road capacity and parking provision. Now there is growing concern at all levels of government that the resulting changes to the built environment and subsequent increases in automobile use negatively impact the livability and sustainability of cities. Unfortunately, these impacts are not well understood and there is limited knowledge regarding alternative approaches to the planning and design of transportation systems. ^ This research incorporates data from 14 small American cities over a period of 50 years to assess the considerable rises in automobile use, the increases in automobile infrastructure, and the associated impacts. The analysis in this study shows that an increase in automobile use of 10 percentage points is associated with an increase of more than 35 square feet of parking per person citywide and a decrease of 4,600 people per square mile. ^ This study also reveals that many cities have experienced increased automobile use for shorter trips within each city, which could easily be served by alternative modes. The evidence suggests this is likely due to improved automobile infrastructure (and a subsequent decay in the environment for walking and biking), intended to serve trips in and out of each city. These shorter automobile trips exacerbate the need for additional infrastructure and could be one potential area to better manage automobile use. ^ Lastly, this work provides an overview of policies that can be implemented which could help place greater emphasis on walking, biking, and transit. The research shows that in cities that have adopted these policies, transportation infrastructure takes up a smaller portion of land and there are considerably greater concentrations of residents and employees. These cases offer valuable lessons in how particular transportation policy can ultimately impact the vitality and the financial viability of cities.