ATSSA: Improving Driver Behavior with Infrastructure Safety Countermeasures

3 American Traffic Safety Services Association • www.atssa.com Introduction A s stated in the overview, roadway crashes are a result of three primary contributing factors: human behavior, the roadway itself, and the vehicle. Frequently there is an overlap between these factors. As shown in Figure 1, human factors or driver behavior is a factor in 95 percent of crashes; however, the roadway environment and vehicle condition also influence crashes. A combination of any or all of these factors may lead to a crash or increase the severity of a crash. Figure 1. Crash contributing factors (Image: New South Wales Roads and Traffic Authority) Example. A young driver in a small vehicle may leave a travel lane due to a distraction; the edge of the pavement may drop off a sufficient depth that results in “scrubbing” of the tire. The driver then overcorrects the situation due to inexperience, and a crash results. Because human behavior (such as distraction, fatigue, speed, alcohol) is the primary contributor to crashes, a typical reaction is that behavior-related crashes can only be addressed by enforcement or educational programs. Research proves—and national best practices endorse— the greatest potential to improve roadway safety is with a comprehensive approach that includes enforcement, education, emergency response, and engineering infra- structure countermeasures. Although infrastructure safety improvements cannot change the initial driver behavior, they can effect change in the sequence of crash events and reduce the severity of crashes. Median-crossover crashes often result when a motorist is speeding, fatigued, distracted, or driving under the influence of drugs, alcohol, or a combination of both. Cable median barrier eliminates median-crossover crashes and reduces the severity of the crash. The following case studies discuss how infrastructure safety countermeasures directly impact driver behavior to improve roadway safety. The studies are grouped according to their ability to alert a driver, provide positive guidance that prevents a collision, or minimize the consequences once a vehicle has left the roadway. This document serves as a resource for better understanding and defining treatments and countermeasures that may reduce crashes or the severity of crashes due to driver behavior. ■