Seasonal 65 mph safety speed limit starts on Interstate 80
52-mile section between Laramie and Rawlins
by Wyoming Department of Transportation
October 12, 2009
A seasonal speed limit of 65 mph will be enforced for six months beginning Oct. 15 to reduce crashes and closures on a 52-mile section of Interstate 80 between Laramie and Rawlins.
The goal of the reduced limit is to give drivers a better chance to safely react to the rapidly changing and extreme weather conditions that can occur on the highway section between the Quealy Dome Interchange 20 miles west of Laramie and the Peterson Interchange 22 miles east of Rawlins.
Over the past five years, the highway section had a crash rate of 1.37 crashes per 1 million vehicle miles traveled, compared with an average rate of 1.1 on rural interstates in Wyoming.
"This particular stretch of Interstate 80 is what we refer to as a high crash frequency area," Wyoming Highway Patrol Col. Sam Powell said. "You can come around a corner and find just terrible conditions that you really have no forewarning of. It’s our belief that asking people to slow down just 10 mph is a small price for them to pay to enhance their safety."
Driving the 52 miles at 65 mph takes slightly more than 6 minutes longer than at 75 mph.
"If we can keep traffic moving safely, the extra time it takes to go through there is insignificant," Powell said. "The savings that we have in terms of the lessened property damage from crashes, but more importantly, fewer injuries and hopefully fewer deaths or no deaths is really what we’re trying to achieve."
Initially, static 65 mph signs will be used on the western end of the section between the Peterson and West Elk Mountain interchanges, and variable speed limit signs will be used on the remaining 35 miles. By mid-December WYDOT expects to have variable speed limit signs in operation on the entire 52-mile section. The variable signs allow further reduction of the limit in 5 mph increments to as low as 35 mph when weather or traffic conditions warrant.
Electronic message signs at Walcott Junction and Laramie will be used to alert drivers to the reduced speed zone ahead and static signs immediately before and within the section also will remind them the seasonal limit is in effect.
"The 10 mph reduction over a relatively small length of the highway gives people that added extra measure of reaction time and braking distance – the things that they will need to avoid a crash out there," Powell said. "That’s really the bottom line for us. It’s keeping people moving through there safely and keeping our personnel out there working safe."
WYDOT implemented the seasonal limit for the first time a year ago, and will gather crash and closure data through another winter to assess the effectiveness of the reduced limit and variable signs.
The University of Wyoming is conducting a 30-month study of the highway section to help determine the effectiveness of the variable speed limit system. The study will continue through February 2010, and also includes analysis of weather sensor data and other factors that can be used to develop a decision support system for setting the appropriate speed for conditions.
Data gathered will help decide whether to continue implementing the seasonal speed limit in the future and whether to install variable speed limit signs on other highway sections in the state.
"This year we’ll put the seasonal speed limit into effect, which will then be augmented by a full season’s worth of the ability to lower the speed limit further by the use of the variable speed limit signs," Powell said. "It’s our belief that by the end of this winter season, we’ll have a very good statistical picture of what the crash data shows us and we’ll make our decision from there."
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