Updated: Construction causes delays on Idaho Highway 67

Seal coating work is under way on Idaho 51 and Idaho 67 in Elmore County, the Idaho Transportation Department announced.

An eight-mile segment of Idaho 51 along Beet Dump Road was already completed, and crews are working on the stretch of Idaho 67 from Mountain Home to the Air Force Base, and southwest down to Grandview, a total of about 24 additional miles.

Seal coating entails spraying liquid asphalt on the highway and spreading a layer of crushed rock over it. A fog coat (so called because it is applied in a "mist" process) is then applied in a light spray over the asphalt to seal the rocks to the surface and prevent fly-away rock chips. Following the application process, a sweeper with a big vacuum is used to remove the excess rocks from the surface.

After the fog coat is applied, it will require a few days before the road can be restriped and returned to the normally posted speed limit.

The purpose of the seal coat is to protect pavement from water and weather damage and to provide a semi-rough surface for improved vehicle traction.

The seal coat will only adhere properly to the roadway surface if reduced speeds are in place until the asphalt-and-rock-chip mixture solidified.

During the work, pilot cars and flaggers will help guide motorists through

the work zone. The road will be reduced from two lanes to one in some

locations, and motorists should expect delays of up to 15 minutes.

Snake River Construction of Twin Falls is the contractor on this $1.14 million project.