ATSSA: Improving Driver Behavior with Infrastructure Safety Countermeasures

7 American Traffic Safety Services Association • www.atssa.com Figure 9. A speed indicator board provides instant feedback to the driver (Image: TAPCO) LEDs are another technology used to improve and enhance driver guidance and help prevent or correct driver error. To enhance the visibility of static roadway signs, LEDs can be inserted along the outline of chevrons or around the circumference of other signs. LEDs can also be used in dynamic-signing applications to provide feedback or to convey a message to drivers only when a certain condition is in effect. For example, flashing speed indicator boards provide instant feedback to motorists about their operating speed, as compared to the regulatory or warning speed at that location. This feedback can improve driver behavior by prompting a reduction to a more appropriate speed for the condition. Similarly, variable speed limit systems use traffic speed and volume, weather, and road surface conditions to determine appropriate speeds at which drivers should be traveling, given current conditions. These advisory or regulatory speeds are conveyed to drivers through overhead or roadside LED variable-message signs. Gap acceptance signs are another LED-based method that enhances safety by providing guidance to drivers at unsignalized intersections. These signs provide red or yellow warning lights that indicate the presence of oncoming vehicles, thereby informing drivers they should wait before attempting a turning maneuver. The Institute of Transportation Engineers (ITE) has published data that indicate a reduction of certain crash types as a result of signs that were installed to address the specific crash types. By providing appropriate guidance, these signs essentially correct previous driver errors by preventing current drivers from making errors. These sign types include curve warning arrows (20 percent crash reduction), advance curve warning signs and speed plaques (20 percent crash reduction), advisory speed signs (36 percent crash reduction) and a special curve warning arrow sign with the stated speed (75 percent crash reduction). Further information from ITE indicates that roadway signs in general could be expected to reduce fatal crash rates (29 percent), injury crash rates (14 percent), and combined fatal and injury crash rates (14 percent), while producing a cost-benefit ratio of 7.3. Information from the Federal Highway Administration (FHWA) indicates that the installation of double stop signs reduces total crashes by 11 percent and right-angle crashes by 55 percent, while advance warning signs reduced total crashes by 40 percent at rural locations. The low cost of signs (for materials, maintenance, and installation) make them the ideal approach to improving roadway safety along roadways and at intersections, particularly if crash history indicates correctable problems do in fact exist. ■