Paul F. Hanley
2004
There are three primary reasons state departments of transportation (DOTs) invest in road and highway upgrades—to promote economic development, to alleviate congestion, and to improve safety. This monograph focuses on the third of these key considerations. Because funds available to finance safety improvements are always quite limited, priority projects must be carefully selected in order to maximize the net safety improvement to society.
An important component of project selection is economic in nature. What are the dollar savings to society of preventing fatalities, injuries, and damage to personal property? For any given proposed project, how do these savings compare to the costs of making the particular investment? An earlier monograph published by the Public Policy Center (Forkenbrock, et al. 1994) proposed a methodology for estimating the safety cost savings of various road upgrades. That methodology and essentially all others depend upon reasonable dollar estimates for fatalities, personal injuries, and property-damage-only crashes. It is the objective of this monograph to suggest current and well-accepted parameter values for preventing each of these types of crashes.
Through telephone interviews of DOT staff in safety and design offices, we were able to obtain the crash values many states are currently using and to gain a sense of how they are applied in investment decisions. We also asked about the role of safety analysis in design exception reviews. The interviews revealed that the majority of DOTs use safety cost savings values recommended by the Federal Highway Administration (FHWA) either to prioritize or to qualify the potential value of proposed projects intended to improve safety.
We also compare how different states prioritize safety improvements. While many use the dollar values for fatality and injury crash costs in their processes, a number expressed concern that several types of analysis tend to skew the ranking of crash locations toward sites where a single fatality has occurred. Some states have attempted to solve this potential distortion by approaches such as weighting costs with criteria like average daily traffic, or by calculating crash costs by crash type or facility type rather than by injury severity. The interviews revealed that a majority of states use benefit-cost analysis to prioritize safety projects.
After analyzing both the values of key parameters used in assessing safety improvements and the methods applied to incorporate these improvements into the investment decision-making process, we offer several recommendations. Specifically, we recommend assigning updated dollar cost values to the three types of crashes, discounting the future benefits of avoided crashes, and discounting any future costs to their present values.
Our research was carried out at the University of Iowa Public Policy Center. Funding for this research was provided by the Iowa Department of Transportation.
$17.95, 70 pp., 8 figures, 15 tables, perfect binding
ISBN 0-87414-144-3