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Finding suitable alternate route during eastern Idaho storms reduces detour from 45 minutes to just 10, enhances safety

Severe dust storms make it necessary to close a lengthy section of Interstate 15 north of Idaho Falls several times each year. During the average year, ITD closes this eastern-Idaho stretch up to five times, with an average closure time of eight hours each occurrence.

The detour route is 28.6 miles in relatively heavy traffic that runs through the northbound off-ramp of Exit 119 on I-15 in Idaho Falls, which is the busiest intersection on the local freeway. This causes congestion that decreases mobility, safety, and economic opportunity, and is inconvenient for the traveling public.

ITD District 6 worked with Jefferson County officials to gain access to Bassett Road, which parallels the interstate and is not greatly affected by dust storms. Using this route will shorten the detour length to the Osgood Interchange (Exit 128) to just 6.5 miles. Meanwhile, this route will bypass the congested and busy intersections, and allow northbound traffic to continue to the Osgood exit, keeping the off-ramp of Exit 119 from becoming severely congested.

Southbound traffic will now get off at the Roberts Interchange (Exit 135), proceed to Bassett Road, and then get back on the interstate at Osgood. Total detour time will be reduced from 45 minutes to less than 10 minutes.

“The current detour route adds significantly to typical motorists on the interstate. The new detour route will only add 0.3 miles. This new route also traverses fewer residential areas and school zones than the old detour course,” ITD District 6 Traffic Engineer Ben Burke said. “This also helps with local-delivery drivers and long-haul drivers staying on time and keeping commerce moving. Further, it is safer for crews setting up closure signs and barricades.”

In addition, every vehicle traveling the new route will save 1 to 3 gallons of fuel, reducing transportation costs and emissions.

Closing the interstate is often a joint operation with the Idaho State Police (ISP). This route helps ISP as well as ITD, reducing the number of accidents, decreasing the amount of time to open and close the road, and lowering the number of personnel required to perform this task.

Assisting Ben Burke with the route innovation and logistics were ITD Maintenance Foreman JR Grotjohn and Crew Lead David Fullmer of District 6’s Idaho Falls shed. The team estimates that the innovation will save approximately $96,000 and up to 667 hours in societal cost based on the average number of closures, average daily traffic, and an assumed value of motorist time.