Driver Performance Comparison of Fluorescent Orange to Standard Orange Work Zone Traffic Signs

Some agencies use durable fluorescent orange sign sheeting on warning signs in work zones. The literature shows that such sheeting is more conspicuous than standard nonfluorescent orange sheeting, but no one has yet demonstrated that the greater conspicuity leads to operational changes or fewer collisions. To investigate that link, operational studies were conducted in seven long-term North Carolina work zones with left-lane drops on multilane highways. The before-and-after with control experiment design was likely immune from common experimental flaws. Five operational measures were collected manually at the beginning of the approach to the work zone, the taper, and midway between the beginning and the taper. Fluorescent orange signs were found to cause some changes, primarily positive, in driver behavior. With fluorescent signs, there were somewhat fewer traffic conflicts, the percentage of vehicles in the left lane at the midpoint was lower, and trucks moved out of the left lane sooner. Mean speeds increased slightly, but usually not significantly, with fluorescent signs, but speed variances tended to decrease with fluorescent signs. The operational changes observed should mean that work zones similar to those in the experiment would experience a small reduction in collisions with fluorescent orange warning signs. Use of fluorescent orange sheeting on warning signs is recommended in work zones like those in this experiment and in other types of work zones where warning drivers is as critical or more critical than it was in this experiment.