Abstract
As the reduction of highway fatalities continues to be a point of emphasis for the U.S. Department of Transportation, many state and local agencies have incorporated safety enhancements into planning, design, operations, and maintenance. In 2010, the American Association of State Highway and Transportation Officials (AASHTO) released the Highway Safety Manual (HSM) as a resource to include safety in decision making for transportation professionals. AASHTO developed general safety performance functions (SPF) to predict crash frequencies based on crash data from various jurisdictions, and suggested that agencies calibrate those SPFs to local crash data and/or develop jurisdiction-specific safety performance functions. At the request of the Idaho Transportation Department (ITD), calibration factors were generated to calibrate the HSM SPFs for rural two-lane, two-way highways and rural stop controlled intersections based on Idaho crash history. In addition, new statewide SPFs were developed for the same rural facilities.