Roadway maintenance projects often require working during nighttime hours in close proximity to ongoing traffic and may reduce traffic flow to a single lane while work is undertaken. In many cases the work is of short duration and a mobile operation. The Oregon Department of Transportation has conducted several research studies to identify best practices for traffic control during maintenance work. Radar speed signs (RSSs) are a traffic control device that has shown promise for positively affecting driver behavior and reducing speeds. RSSs use radar technology to measure the speed of oncoming vehicles and display the vehicle speed and accompanying messages to the drivers. This research study evaluated the impact of truck-mounted RSSs on vehicle speeds in maintenance work zones and identified best practices for their use as part of mobile and stationary maintenance work operations. The research study includes four case studies on multi-lane maintenance projects in Oregon. On each case study, the researchers conducted two periods of testing: one with the RSS display turned on and one without the RSS display turned on, and recorded vehicle speeds. The research findings indicate that vehicle speeds are typically lower and there is less variation in speeds between adjacent vehicles with the RSS turned on. Based on the findings, the researchers recommend use of truck-mounted radar speed signs during mobile maintenance operations on high-speed roadway. (Author/publisher)
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