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ITD to install variable-speed signs on section of I-15

To improve traffic safety and mobility on Interstate 15 north of Osgood, the Idaho Transportation Department (ITD) will install variable-speed signs to slow traffic when blowing dust reduces visibility.

Crews will install signs north of the Osgood interchange on a 1.5-mile stretch (between mileposts 128 and 130) that is highly susceptible to dust storms when fields are bare and winds are high.

The solar-powered signs will post 80 mph limits unless reduced visibility calls for lower speeds, at which time officials will adjust the posted speed limits wirelessly. Data from ITD's Osgood weather station will identify proper speeds.

ITD personnel will place two sets of signs for times when incremental reductions in speed are necessary to meet conditions.

If visibility data call for speeds lower than 40 miles per hour, ITD will close the freeway, since visibility will be dangerously low.

ITD poured foundations for the new signs Monday (Oct. 19). After the foundation concrete cures, crews will begin installing signs later this month.

Surrounding states have variable-speed signs, but these are the first such signs in Idaho.

Weather stations along highways in Idaho are equipped with visibility sensors, but ITD has never used data from these sensors to set speed limits.

The variable-speed signs will help enable ITD to keep I-15 open a little longer before poor visibility closes the route.
Driving in dust storms, of course, is very dangerous. The 1.5-mile stretch has experienced several vehicle pileups over the years. Pictured above is a crash resulting from a dust storm in 2007.

"ITD works closely with the Idaho State Police (ISP) in developing countermeasures to dust storms, forecasting conditions that result in such storms, and responding," said ITD District 6 Engineer Kimbol Allen.

"Whether it is dust, snow or rain, we remind motorists to always consider the weather and road conditions when driving," said Lt. Chris Weadick, of ISP. "If common sense tells you it is unsafe to drive the speed limit, please slow down and give yourself more space to stop."