OTREC-RR-12-02

The Highway Safety Manual (HSM) published by the American Association of State Highway and Transportation Officials in the spring of 2010 includes safety predictive methods which are used to estimate the safety of a transportation facility. However, the safety performance functions (SPFs) were developed for states other than Oregon. Because of differences in crash reporting, driver and animal populations, and weather conditions, officials need calibrated SPFs for Oregon facilities. Predictive methods were developed for rural two-lane roads, rural multilane roads, and urban/suburban arterial roads. In this project SPFs were calibrated for these facility types based on their historic performance in Oregon. The report illustrates methods of site selection, collection of crash and site data, analysis methods, and an evaluation of crash severity distribution methods. Oregon agencies can use calibrated HSM predictive methods to more accurately assess expected facility safety performance for Oregon conditions.