Simulator study of primary and precipitating factors in work zone crashes

Research with a driving simulator was conducted to determine the impact of various primary and precipitating factors on work zone crashes and associated driver performance. The primary factors included in the study were roadway type (undivided and divided), traffic density (low, moderate, and high), and work zone type (lane closure and shoulder closure). Precipitating factors included elements that caused the driver behavior or the environment to change and initiate the potential for a crash, near crash, or incident. Twelve precipitating factors were investigated; all could be described as involving either a stopped or slow vehicle in the travel lane or an object in the roadway. Forty-five participants were exposed to 24 different work zone configurations for which performance measures of crash frequency, speed, lane deviation, and deceleration data were collected. The performance measures were used to determine the most hazardous work zone configurations. Neither the level of traffic density for mean speed nor the type of roadway for lane deviation was found to be statistically different. The remaining statistical test rejected the null hypothesis that the performance measures were similar. Overall, the most hazardous work zone configurations entailed a divided roadway with a lane closure during low-density traffic conditions and a stopped or braking truck or car.