Drilling and trenching work for fiber-optic cable installations is affecting traffic this week on two key highways, the state Department of Transportation announced.

Contraflow traffic will be in effect on Honoapi'ilani Highway at Ma'alaea from 9 p.m. and 5 a.m. through Friday, with the Lahaina-bound lane from Ma'alaea Road to the Kaheawa wind farm closed during that period, the DOT said.

On Pi'ilani Highway in Kihei, a single northbound lane will be closed from 8:30 a.m. to 3:30 p.m. through Friday.

The DOT is urging motorists to drive cautiously through the project areas and to allow extra travel time.