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 on the ability of drivers to detect low-contrast objects and workers wearing high-visibility vests. Three lighting conditions were set up: 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 a low-contrast object (a box, a target, and a tire). Researchers also confirmed that drivers tended to overdrive their headlights, especially in rural, dark scenarios. Compared with the results for the dark scenarios, the results for the illuminated roadway section showed that properly installed temporary work zone lighting could increase the distance at which workers and low-contrast objects could be detected. The results also confirmed that improper positioning of portable light towers had a negative impact on the distance at which workers and low-contrast objects could be detected and supported the theory that direct illumination by portable light towers could visually wash out workers and thus could make them more difficult to detect.