Application of the Highway Safety Manual to predict crash frequency

The American Association of State Highway Transportation Officials (AASHTO) published the first edition of the Highway Safety Manual (HSM) in July 2010. The HSM provides a comprehensive set of tools for managing and measuring safety. As a guidebook it outlines methods for developing and managing a roadway safety management system, a catalogue of crash modification factors for various features, and a method to predict average crash frequency and severity. The predictive method of the HSM will allow agencies to forecast the change in crash frequency or severity on a roadway due to changes in traffic volume or roadway geometry. The City of Missoula, Montana, USA, conducted a corridor planning project on a 2.4 km segment of Russell Street, a minor arterial with average daily traffic (ADT) volumes of 20,000 vehicles per day. The project quantitatively assessed the change in future crash frequency for seven scenarios of differing traffic volumes, intersection control, cross sections, and levels of access management. The quantitative safety analysis results were combined with traffic operations and environmental analyses to inform the decision process for selecting a final concept. This paper presents an overview of the HSM predictive methodology; a discussion of its application to the Russell Street corridor; and, discussion of the method's general application in Australia. (a) For the covering record of this conference, please refer to ITRD abstract no E220725.