Transportation officials say rock blasting will force closures twice a week for the next 10 weeks on a stretch of Interstate 15 near the California-Nevada state line.
Caltrans officials say travel lanes will be closed at 10 a.m. for up to 90 minutes every Tuesday and Thursday morning between Bailey and Nipton roads near Wheaton Springs, Calif.
Motorists heading to Las Vegas are being encouraged to wait in Baker, Calif.
Drivers traveling to California are being advised to wait in the state line town of Primm.
The $91 million project is to widen about 12 miles of I-15 through Mountain Pass.
The blasting schedule is expected to be completed by the end of October. The entire project should be finished in fall 2010.