Impact of Work Zone Lighting on Driver’s Detection of Objects

Researchers conducted a closed-course study to evaluate the impact of work zone lighting upon the ability of drivers to detect low contrast objects and workers wearing high-visibility vests. Three lighting conditions were setup: no lights (dark or base condition), a portable, trailer-mounted light tower, and a portable balloon light. The dark scenario treatments confirmed that a worker wearing a retroreflective vest could be detected at significantly longer distances than low-contrast objects (i.e., box, target, and tire). Researchers also confirmed that drivers tend to overdrive their headlights, especially in rural, dark scenarios. Compared to the dark scenarios, the illuminated roadway section results showed that properly installed temporary work zone lighting can increase worker and low-contrast object detection distances. The results also confirmed a negative impact on worker and low-contrast object detection distances from improper positioning of portable light towers, and supported the theory that workers can be washed out visually when directly illuminated by portable light towers, making them more difficult to detect.