Crumbling asphalt is forcing Caltrans to begin an about three-week project to repair about nine miles of Highway 29 in Lakeport, and drivers likely will face some traffic slowdowns.

Crews on Wednesday are to start working 12-hour days to grind off the top layer of asphalt from just north of Highway 175 in Lakeport to just south of Mockingbird Lane to the north before repaving the road. The work is expected to be finished by Aug. 13.

Traffic will be limited to one lane in each direction from 4 a.m. to 4 p.m. weekdays. On Wednesday, the southbound ramp to 11th Street will be closed 9 a.m. to 4 p.m. Beginning Monday, July 26, ramps for Lakeport Boulevard, 11th Street, Park Way and Nice-Lucerne Cutoff Road will be closed intermittently, but no more than one ramp will be closed at a time, Caltrans said.

Caltrans spokesman Phil Frisbie the nearly $4 million project was prompted when Caltrans engineers realized that the asphalt was turning into gravel at a much faster rate than expected, possibly due to temperature changes in past springs, especially this past spring. He said Caltrans has been sweeping the highway twice a week to remove the gravel.

The new asphalt will include rubber ground up from an estimated 62,000 car tires. Caltrans said rubberized asphalt is more flexible than regular asphalt and lasts longer.