Evaluation of traffic control countermeasures to improve speed limit compliance in work zones on high-speed roadways

Abstract

Slowing motorists within work zones on high-speed roadways continues to be a challenge for highway operators in all jurisdictions. The New Brunswick Department of Transportation and Infrastructure (NBDTI) utilizes procedures outlined in the Work Area Traffic Control Manual (WATCM) to manage speeds within work zones. The WATCM states the posted limit in work zones may not be more than 20 km/h less than the prevailing posted limit due to previous research indicating a larger reduction will increase the risk of collision. Workers on high-speed facilities are exposed to speeds of 90 km/h and greater. This study aims to identify traffic control countermeasures that will allow a further reduction below 90 km/h while maintaining speed limit compliance. The countermeasures tested included each, as well as combinations, of the following: Floating Speed Zones (FSZ); Traffic Control Person (TCP); Narrow Lanes; Radar Speed Display Board (RSDB); Variable Message Sign (VMS); Fake Police Vehicle. The top ranked countermeasures in terms of speed reduction were found to be the following combinations: the TCP and the FSZ; the Fake Police Vehicle and the FSZ; and the RSDB and the FSZ. The TCP/ FSZ, Fake Police Vehicle/ FSZ and the RSDB/ FSZ resulted in mean speed reductions of 23 km/h, 19 km/h and 19 km/h, respectively. Implementation of the countermeasures did not significantly increase speed variance. It is recommended that NBDTI incorporate a provision within the WATCM to allow reductions to 70 km/h as long as a RSDB or a TCP is used as a supplemental countermeasure.