ATSSA: Improving Driver Behavior with Infrastructure Safety Countermeasures

12 Improving Driver Behavior with Infrastructure Safety Countermeasures Figure 18. HFST in Placer County, Calif. (Image: Richard J. Baker, DBi Services) Part II: Providing Positive Guidance and Enhancing the Infrastructure to Prevent Collisions CASE 6: Skid-Resistant Surfaces and the Safety Edge SM S kid-resistant roadway surfaces help a vehicle’s tires maintain contact with the road through horizontal curves and in curves at inappropriately high speeds. High- friction surface treatments (HFST) can also help prevent the vehicle from departing the roadway. HFST is a thin layer of durable aggregates (typically calcined bauxite) that is highly resistant to “polishing” or wear. The aggregate is bonded to the asphalt, concrete, or other pavement surfaces using polymer binders. When this treatment was applied to 75 Kentucky locations in 2010, roadway-departure crashes decreased by 91 percent in wet weather and 78 percent in dry weather conditions. Another low-cost roadway safety improvement that helps prevent crashes is the Safety Edge SM , which provides an opportunity for a driver who has drifted off the pavement near a vertical edge drop-off to return to the pavement safely before a crash occurs. This feature is extremely effective on rural roads with unpaved shoulders. This treatment mitigates the vertical elevation difference by sloping the edge of the pavement to 30 degrees during paving or resurfacing projects. An evaluation conducted at 261 treated sites (685 miles) in Georgia and 148 sites (514 miles) in Indiana showed a 5.7 percent reduction in total crashes, based on crash data of six years before and three years after resurfacing the study sites in Georgia and those of two years before and three years after in Indiana. This low-cost roadway safety treatment also resulted in high benefit-cost ratios, based on crash reductions. ■ Figure 19. Federal Highway Administration’s (FHWA’s) Andy Mergenmeier and Chris Wagner gathering data on a new Safety Edge SM project (Image: Frank Julian, FHWA) Figure 20. Note the tire tracks on the shoulder and onto the roadway. The edge of the Safety Edge SM remained unharmed after being crossed by a fully loaded asphalt truck during road construction (Image: Frank Julian, FHWA)