TOOL Recommended Actions to Help Transportation Agencies Implement the Highway Safety Manual P By Darren J. Torbic, Ph.D. (M) erformance-based processes that use data-driven safety performance measures offer potential for state and local transportation agencies to reduce the number of traffic fatalities and serious injuries that occur on the nation's highways and to make informed decisions to reduce project and operating costs. The American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM) provides safety knowledge and tools to facilitate improved decision making based on safety performance.1 The HSM enables transportation agencies to use performance-based statistical approaches when designing for the safety performance of a facility, rather than simply adhering to traditional design policies and standards, such as the AASHTO A Policy on Shutterstock/Trong Nguyen Geometric Design of Highways and Streets and the Manual on Uniform Traffic Control Devices.2,3 w w w .i t e.or g J u ne 2021 45http://www.ite.org