Vehicle Miles Traveled as a Metric for Sustainability

Motor vehicle travel provides many benefits, but also imposes large economic, social and economic costs. A new Institute of Transportation Engineers report, Vehicle-Miles Traveled (VMT) as a Metric for Sustainability, can help guide planning to optimize the amount people drive.

This is an important and timely issue. Per capita vehicle-miles traveled (VMT) grew steadily during the Twentieth Century. During the growth period, transportation agencies applied “predict and provide” planning practices that contributed to a self-reinforcing cycle of expanded roads, more parking subsidies, reduced non-auto travel options, and sprawled development patterns that created automobile-dependent communities where it is difficult to get around without a car. 

Per capita motor vehicle travel peaked about 2005, and current demographic and economic trends (aging population, rising vehicle costs, changing consumer preferences, increased health and environmental concerns) are increasing non-auto travel demands. In response, many transportation agencies are shifting from mobility-oriented planning, which assumed that our goal is to maximize travel speed and distance, to accessibility-oriented planning, which recognizes the ultimate goal of transportation is to provide access to services and activities, and policies intended to increase mobility often reduce accessibility in other ways.

To achieve sustainability goals, many jurisdictions are now reforming their planning practices to support accessibility-based planning. Some have established vehicle travel reduction targets to help guide these reforms. These policies can be justified for several reasons: to support more multimodal planning, to reduce traffic congestion, to reduce road and parking infrastructure costs, to reduce pollution emissions, and to improve community livability, public fitness and health.

This report discusses how much vehicle travel can be reduced, appropriate analysis methods and planning practices, and effective VMT reduction strategies. It also includes case studies from locations that optimized vehicle travel in the United States and internationally.