Prioritizing improvements to truck driver vision

Abstract

This report presents the results of a three-part study of truck driver exterior vision and its safety consequences. In part one, crash data are analyzed to document vision-related truck crash issues. About 20% of truck-initiated crashes occur in configurations in which limitations to truck driver vision may have been an important factor contributing to the crash. Right-going lane changes and turns account for more than half of these crashes. On average, right-going truck-initiated crashes are about 4.5 times more likely than left-going crashes. Non-motorists killed in startup and right-turn crashes were nearly all adults and tend to be older the pedestrians struck in other crash modes, suggesting that near-field truck vision analyses should focus on adults rather than children. Over half of pedestrians involved in start-up crashes are over age 65. An experimental study showed that driver performance in detecting lane-change conflicts was directionally consistent with the findings from the crash data. Drivers took longer to detect conflicts on the right side of the vehicle than on the left. The longest reaction times were observed when the target vehicle was directly to the right of the cab, suggesting that detecting a conflict in this area is most difficult for drivers. Drivers also made more errors on the right side of the vehicle, including several failures to detect a vehicle directly to the right of the cab. Based on these findings, a prioritized set of vision zones was developed. The highest priority for improvements to driver vision is the area directly to the right of the truck cab. This area represents the most likely position of a crash partner at the truck driver’s decision point in right lane-change crashes and is also the pre-crash position of many non-motorists involved in right turn and start up crashes. This report presents a new approach to evaluating exterior vision from truck cabs. The method differs from previous approaches, e.g., SAE J1750, by providing an aggregate score that is related to a specific crash-safety issue. The method is based on the visibility of standing adult pedestrians, and hence addresses the specific problem of pedestrian involvement in start up and right turn crashes. The experimental paradigm presented in Section 3 also represents a promising approach to evaluating the quality of exterior vision provided by alternative vision systems. The time drivers require to determine if a conflict exists provides a sensitive measure of the difficulty of the task. The parallels between the findings of the experimental study and the crash data analysis support the validity of the experimental approach. This method could be applied to evaluate alternative mirror systems, camera-based systems, and other technologies that might be developed to address the priorities established in this report.