Driving Simulator Studies of the Effectiveness of Countermeasures to Prevent Wrong-Way Crashes

Wrong-way crashes (WWCs) are severe and more likely to be fatal compared to other highway crashes. The authors report two tasks aimed at understanding and reducing this type of crash. Task 1 was a review of five decades of research on the characteristics of wrong-way drivers, interchange designs associated with wrong-way entries, and the effectiveness of countermeasures that have been implemented to reduce wrong-way crashes and entries. Task 1 also involved the development of a cue-based decision model to explain wrong-way movements. Task 2 included laboratory and driving simulator studies to better understand effective countermeasures to prevent wrong-way entries and crashes, testing younger and older drivers under conditions in which they are most likely to be involved in a WWC (younger drivers at night, older drivers during the day). A subset of younger participants was asked to drive scenarios while under conditions of simulated impairment (with visual distortion and under cognitive load). Within the context of the previously proposed cue-based decision framework, the goal was to understand the most effective cues to convey to drivers of all ages information about correct and incorrect interstate entry points so they can make safe and accurate driving decisions. Since wrong-way entries are rare events, in the simulator, the authors explored a number of potentially more sensitive metrics to detect driver confusion at interchange decision points (e.g., lane deviation, speed, braking behavior). A non-simulator decision task involving photos of interchanges was also conducted to understand the best countermeasures to quickly alert drivers regarding correct and incorrect entry points. The decision task revealed that the visibility of wrong way (R5-1a) signs was one of the best predictors of correctly rejecting an exit ramp with respect to countermeasures. The presence of other vehicles was also a strong predictor of accuracy, consistent with the fact that many WWCs occur at night with few other vehicles on the road. In general, a greater number of different types of countermeasures present benefited the correct rejection of exit ramps in the decision task. Both younger and older adults benefited from an increase in diversity of countermeasures. In addition to a greater variety of countermeasures, the presence of redundant signs (Wrong Way, Do Not Enter) improved the identification of exit ramps, though in this case, more so for younger adults compared to older adults. In the simulator task, drivers (N = 120) were instructed to enter a highway, and exit ramps were marked with the minimum number of countermeasures recommended by the Manual on Uniform Traffic Control Devices (MUTCD) or with a greater number of countermeasures and countermeasure enhancements recommended by a recent analysis of Florida exit ramps by the Florida Department of Transportation’s Statewide Wrong Way Crash Study. A total of four wrong way entries were observed (2 older drivers, two younger drivers under conditions of simulator impairment). All four occurred in the minimum countermeasure condition. Evidence also suggested that speed and braking patterns differed as a function of countermeasure configuration, highlighting the potential of subtle driving behavior measures as indicators of driver confusion/uncertainty. Overall, results of the simulator study provide initial evidence that countermeasure configurations including a greater number and greater diversity of countermeasures may assist in reducing confusion regarding entrance and exit ramps. However, some caution is warranted with respect to claims of reducing the number of wrong-way entries as statistical significance is difficult to achieve when investigating such low probability events in the absence of very large samples. Based on the developed decision model and the results of the ramp classification and driving simulator task, new countermeasure standards that increase the number and diversity of countermeasures at exit and entrance ramps are a promising approach to reduce this dangerous type of crash.