Wyoming Variable Speed Limit and Dynamic Message Sign Program
Electronic variable speed limit and dynamic message signs, along with web cams and sensors, create a holistic approach in preventing crashes across Wyoming’s transportation infrastructure. The state, known for its severe winds and quickly changing weather conditions, uses this advanced technology to tailor speeds matching changing highway road conditions in short segments. The Wyoming Department of Transportation’s (WYDOT’s) long-term studies determined that unsafe speed accounted for 70 percent of winter crashes in Wyoming.
Electronic variable speed limit signs allow WYDOT to alternate speed limits when weather and road conditions deem necessary, often reducing speeds to help prevent closure frequency caused by crashes. Closing the interstate is inconvenient for drivers—but it can also have national economic impacts. The average interstate closure in Wyoming is 8 hours and often results in a cumulative impact of $8 to $12 million dollars to freight carriers. In areas where signs are used, sensors are embedded in the pavement and installed alongside the road to help control traffic flow. Since travel speed depends upon each driver, speeds can vary widely. This variance in speed can cause safety issues. These signs help to pull outliers into a pace speed and reduce closure-causing crashes. Used in conjunction with variable speed limit signs, dynamic message signs keep motorists informed about road conditions while they travel, providing information about impending weather situations, traffic, or anticipated storms.
WYDOT continues to add signs and sensors throughout the state as statistics show a positive return on investment. Areas, where this method is employed, have seen fewer road crashes and closures. By investing in these safety measures, WYDOT has helped drivers avoid crashes by knowing when to slow down for road conditions.