MA'ALAEA, Maui — Rock-scaling work on the slopes above the pali section of Honoapi'ilani began yesterday and will cause nighttime traffic delays over the next week.

The $3 million emergency project was launched to remove chunks of the steep mountainside that were cracked and loosened by the Oct. 15 earthquakes, posing a threat to motorists on the two-lane highway below, said Maui District Engineer Fred Cajigal of the state Department of Transportation.

The highway is the main link between West Maui and the rest of the island. Portions of the cliffside were covered with nets years ago to protect passing cars from falling rocks, but some of the newly loosened landscape is above those areas.

The scaling work will be conducted on the Ma'alaea side of the pali tunnel from 9 p.m. to 5 a.m. through Tuesday. The Lahaina-bound lane will be closed near Milepost 9 about a mile east of the tunnel, with vehicles allowed through on a contra-flow basis.

Electronic message boards are being used to advise motorists of traffic delays, which are expected to be at their worst between 9 and 11 p.m.

No work has been scheduled for New Year's Eve or New Year's Day, Cajigal said.

The 3.3-mile rockfall mitigation project includes rock and boulder removal, drilling and installation of anchors for safety lines for the work crews, placement of netting along the slopes next to the highway to catch loose material, and shotcrete, a process in which concrete or mortar is "shot" under pressure onto a surface to provide stabilization.

The state awarded the job to Jonad, a company specializing in rock stabilization and similar work.

The first phase of the scaling project will be done on nine slopes before workers tackle another section of mountainside toward Ma'alaea. Cajigal said the entire project is expected to be complete by February.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.