Evaluation of Three Supplementary Traffic Control Measures for Freeway Work Zones

Controlling traffic in work zones to improve safety has long been a major concern for highway agencies. Three traffic control devices- white lane drop arrows, orange rumble strips, and the CB wizard alert system-were tested for their effectiveness in improving merging and reducing speed and speed variance at an interstate highway work zone in Missouri. Results of implementing the white lane drop arrows and the CB wizard alert system indicate decreases in the percentage of vehicles in the closed lane, mean speed, and speed variance. It also appears that the CB wizard alert system may be more effective than the white lane drop arrows. The CB wizard alert system in conjunction with the orange rumble strips did show similar reductions, but they were much smaller in comparison to the CB wizard alert system alone.