Safe and Effective Speed Reductions for Freeway Work Zones Phase 2

Freeway pavement preservation projects typically require construction workers to conduct their work in close proximity to ongoing traffic and often reduce traffic flow to a single lane while work is undertaken in an adjacent lane. During the lane closures, the paving operations place workers on the roadway within a protected work zone. The Oregon Department of Transportation (ODOT) conducted a research study to investigate the impact of 35mph advisory signs, located periodically in the work zone, on vehicle speeds within highway paving project work zones. The research study, which follows two similar studies that addressed other traffic control devices (SPR-751 and SPR-769), centered around one case study on a multi-lane paving project in Oregon. On the case study, the researchers implemented the 35mph advisory signs along with other traffic control devices (“Speed 50” signs with radar speed display, and Portable changeable message signs (PCMS) signs on rollers) and evaluated the impact of the 35mph signs on vehicle speed and speed variability. The research findings indicate that using the 35mph signs leads to lower vehicle speeds within the work zone. The reduction in speed is greater for passenger cars than for trucks. Use of 35mph advisory signs in future ODOT work zones is recommended to help reduce vehicle speeds through the work zones.