State officials said efforts to improve safety at H-3 freeway’s Harano Tunnels will continue, with a single-lane closure scheduled on the Kaneohe-bound side, starting Friday.

From 7 a.m. to 3 p.m., a single-lane closure is scheduled before and after the tunnels — approximately 2,000 feet before the entrance to about 250 feet past the exit — as crews cut grooves into the concrete to improve traction.

The closure will continue from 7 a.m. to 3:30 p.m. Monday through Friday into early February, the Hawaii Department of Transportation said.

Crews regrooved the Honolulu-bound lanes earlier this month, and the work has now moved to the other side of the tunnel. Future work will include installation of delineators, or flexible plastic poles, at the edges of the travel lanes, along with lane markings.

The improvements are designed to improve safety, and encourage drivers to slow down, state officials said. The posted speed limit approaching the tunnels from Kaneohe is 45 mph, and the speed limit within the tunnels is 55 mph.

Motorists should drive with caution and plan for extra travel time during work hours. Estimated travel times and camera views for the H-3 freeway and other Koolau routes are available at GoAkamai.org.