Texas Transportation Institute

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This two-page report summarizes the research performed in Project 0-5439, Identifying and Testing Effective Advisory Speed Setting Procedures. The project was conducted by the Texas Transportation Institute, a member of the Texas A&M University System, in cooperation with the Texas Department of Transportation. The objectives of this project were to develop guidelines for determining when advisory speeds are needed to maintain safe operation, develop criteria for identifying appropriate advisory speeds, and develop a cost-effective method for determining the advisory speed for a given curve. The objectives were achieved by evaluating the crash history of sharper curves in Texas, evaluating car and truck driver curve speed choice, developing recommended guidelines and procedures for setting advisory speed in conjunction with other warning signs and devices that enhance pavement edge delineation, and evaluating the effects of the recommended guidelines through field testing. Researchers found that having a consistent, uniform display of advisory speeds on curves of similar geometry, character, and road surface condition is more likely to achieve the desired safety benefits. Researchers developed a consistent method for determining advisory speeds called the "compass method" and produced the Horizontal Curve Signing Handbook, which contains technical guidance to accurately identify advisory speeds and promote uniform application of curve warning signs in Texas. Contact information and websites are given for more information.