Identifying and Testing Effective Advisory Speed Setting Procedures

Project Description

Research has shown that the average crash rate for horizontal curves is about three times that for a tangent road section. Warning signs are intended to improve roadway safety by providing the driver with a warning of conditions that may not be apparent or expected. However, several research project conducted in the last 20 years have consistently shown that drivers are not responding to the alignment warning signs nor complying with the advisory speed plaque. These researchers have advocated the need to establish a procedure for: (1) identifying when a curve warning sign and advisory speed plaque is needed and (2) selecting an advisory speed that is consistent with driver expectation. They also recommend the uniform use of this procedure on a statewide or nationwide basis such that driver respect for alignment warning signs is restored and curve safety records improved. The objectives of this research are to: (1) develop guidelines for determining when advisory speeds are needed to maintain safe operation, (2) develop criteria for identifying appropriate advisory speeds, and (3) develop a cost-effective engineering study method for determining the advisory speed needed for a given curve.

Project Publications

Development of Guidelines for Establishing Effective Curve Advisory Speeds 0-5439-1

Identifying and Testing Effective Advisory Speed Setting Procedures 0-5439-S

Horizontal Curve Signing Handbook 0-5439-P1

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