Safety and Highway Investment

David J. Forkenbrock
Norman S. J. Foster
Thomas F. Pogue
June 1994

One of the principal reasons governmental agencies invest in better highways is to improve safety. Safer roads reduce the likelihood of personal injuries, property damage, and even loss of life due to accidents. To determine whether safety and other benefits would be great enough to at least equal the costs of a highway investment, state departments of transportation often conduct benefit-cost analyses.

How safety improvements should be taken into account in highway benefit-cost analyses has never been completely clear. A major part of the uncertainty pertains to placing a dollar value on reductions in the risk of fatalities and personal injuries. No uniformly accepted dollar values exist, nor is consensus likely. For safety improvements to be given proper weight, however, we must estimate the values of preventing fatalities and injuries.

Similarly, it is difficult to estimate the probable reduction in accident rates (risk) that would result if a particular highway improvement were undertaken. Many road characteristics affect accident rates, and these characteristics interact with each other. They also interact with other factors such as driver performance, vehicle condition, and meteorological conditions, as well as changes in flow speed and traffic volume that result from the highway improvement itself.

This monograph examines issues related to the valuation of accident cost saving and the estimation of accident rate reductions likely to be associated with highway investments.

Research for this project was carried out at the University of Iowa Public Policy Center. Funding was provided by the U.S. Department of Transportation, University Transportation Centers Program. This program was created by Congress in 1987 to "contribute to the solution of important regional and national transportation problems." Following a national competition, the program established university-based centers in each of the tend federal regions. The Midwest Transportation Center that funded this project is one of those centers' it is a consortium that includes Iowa State University and the University of Iowa. Matching funds were provided by the Iowa Department of Transportation, which also provided the extensive data needed to complete this project. Additional matching funds were provided by the University of Iowa Injury Prevention Research Center, which is supported by the U.S. Centers for Disease Control and Injury Prevention.

The research team has benefits greatly from its collaboration with a five-member project advisory committee. This committee helped to focus the issues to be addressed, and its members shared their insights throughout the research process.

$12.95, 53 pp., 11 figures, perfect binding