Analysis of Design Attributes and Crashes on the Oregon Highway System

Since the passage of the Highway Safety Act of 1966, state departments of transportation have engaged in systematic safety improvement planning and programming. According to Davis (2000), the general approach to safety improvement planning employed by most states follows six principal steps: 1. Identification of hazardous roadway locations using crash records; 2. Detailed engineering study of selected hazardous locations to identify roadway design problems; 3. Identification of potential countermeasures; 4. Assessment of the costs and benefits of potential countermeasures; 5. Implementation of countermeasures with the highest net benefits; 6. Assessment of countermeasure effectiveness following implementation. All planning processes are subject to uncertainty. In safety improvement planning, the determination of benefits from implementation of countermeasures depends greatly on projected crash reductions. Such projections are acknowledged to be the most uncertain element of the safety planning process (Pfefer et al., 1999). More than 25 years ago Laughland et al. (1975) identified the need for development of a national comprehensive set of crash reduction factors (CRFs) that states could employ in evaluating safety countermeasures. However, this need has not been addressed, and is not likely to be pursued (FHWA, 1991). As a result, states have been responsible for developing their own CRFs