Impact of Advisory Signs on Vehicle Speeds in Highway Nighttime Paving Project Work Zones

Pavement preservation projects typically require construction workers to conduct their work in close proximity to ongoing traffic. During paving operations, workers are located within a protected work zone. Some are situated nearby or engaged with the equipment, while others may be a long distance from the equipment and on foot. The study reported here was conducted to investigate how temporary advisory speed signs located periodically in a work zone affected vehicle speeds within highway paving project work zones. The study used an experimental approach that involved a multilane paving project on a high-speed roadway in Oregon. The posted regulatory speed on the roadway was 65 mph, which was reduced temporarily to 50 mph in the work zone. During construction, 35 mph advisory signs were posted along with other traffic control devices (e.g., “Speed 50” signs with radar speed display and portable changeable message signs on rollers), and the impact they had on vehicle speed and speed variability was evaluated. The research findings indicated that use of the 35 mph signs led to lower vehicle speeds within the work zone. The reduction in speed was greater by passenger cars than by trucks. The use of 35 mph advisory signs in work zones is recommended to help reduce vehicle speeds through the entire work zone and to minimize safety risks, especially to workers on foot and situated away from major equipment.