ITD installing variable speed limit signs on portion of I-15

Regular drivers who use I-15 north of Idaho Falls will start to see a few changes in the coming weeks, variable speed limits.

Along a mile-and-a-half stretch of interstate just north of the Osgood exit, drivers will see new electronic speed limit signs that could potentially be lower than the standard 80 mph posted limit. The Idaho Transportation Department says the main focus for putting the variable speed signs is to help drivers during dust storms.

“That area in particular is prone to dust storms when fields are dry and winds are high,” said Bruce King with the Idaho Transportation Department. “By installing these variable speed signs, we’re hoping that by slowing drivers down, we don’t have to shut the interstate down as quickly.”

ITD is installing two sets of speed signs on each side of the road in 1/5 mile increments. Legally they’re allowed to drop the speed limit in 20 mph increments, meaning drivers could see the speed drop from 80 mph to 60 mph, and then to 40 mph in less than half-a-mile. “If the data suggests the speed limit should be less than 40 mph, that means visibility is very low and we’ll probably close the interstate,” said King

King said the stretch of freeway north of the Osgood Area has had several multi-car pileups past years caused by poor visibility and drivers moving too fast.

Drivers in the area will see the variable signs shortly as construction crews are already installing the foundations.

This is the first example of variable speed limit signs in Idaho, though King said similar signs have been installed in other states across the country.