Regent’s Slide stabilization effective, repairs advance at Highway 1 site
BIG SUR – Slope stabilization efforts at Regent’s Slide on Highway 1 have been effective in helping sustained excavation activity at the site where traffic along the Big Sur Coast remains blocked.
Regent’s Slide — at post mile 27.8, and about 40 miles south of Carmel — has blocked travelers along the famed coast highway through Monterey County since it occurred Feb. 9, 2024. Crews began top-down removal of slide material on April 30, 2024. Regent’s Slide originated 450 feet above the roadway, displacing material that engulfed Highway 1 and continued down to the beach and ocean below.
Over time, continued slide activity in and around the repair site, along with the height, steepness and instability of the slide area, has been a challenge crews have faced, sometimes bringing work to a halt. The introduction of remote-controlled equipment at the site allowed operators to take more risk while increasing production and worker safety.
By May of this year, crews began installing dozens of shear dowels, steel bars about 60 feet in length, into the slope above the work area. The shear dowels are drilled into the slope and grouted in place in a 10-foot by 10- foot grid fashion.
The primary function of shear dowels is to reinforce the slope by increasing its internal shear strength. By anchoring the unstable soil layers to more stable underlying materials, they help resist the forces that can cause landslides. This method is particularly effective in areas where traditional excavation or grading is not feasible due to environmental concerns or terrain challenges.
This engineering strategy allowed other phases of the repair to begin and provided a safer environment for workers, said Caltrans in a previous report. Last month it said the slope had been reinforced with 20 miles of steel bars and eight million pounds of cement — enough cement to fill 533 trucks and enough steel to stretch halfway to Carmel.
Full-scale excavation work has continued at Regent’s Slide since mid-July with crews able to sustain production in part due to the effectiveness of the installation of the thousands of shear dowels.
Data from an array of monitoring equipment has confirmed that the shear dowels are having the intended effect of mitigating further slide activity which has been a characteristic feature of repairs at Regent’s Slide, said Caltrans. As the top-down excavation advances, crews will continue to install shear dowels in the cut slope behind them, providing immediate and long-term reinforcement of the slope. Since mid-July, crews have installed an additional 1,500 dowels, bringing the overall total number of installed shear dowels to 3,500.
Excavation work is advancing with the combined use of both conventional and the remote-controlled equipment, which includes two large bulldozers and one excavator, and remains an integral component to the advancement of excavation and removal of slide material. Even as seasonal patchy coastal fog has intermittently cut into full production, crews continue to work seven days a week and extended hours on these repair efforts.
Caltrans remains in a position to announce a refreshed date for the full reopening of Highway 1 at Regent’s Slide in mid-September.
Once work at Regent’s Slide is complete, it would open up Highway 1 to direct travel between Carmel and Cambria.
Currently, visitors coming from the north are able to travel to Big Sur, its businesses and surrounding area up to the northern-most closure point at Lime Creek — post mile 32.1 — just south of the Esalen Institute, while travelers from the communities of Cambria, San Simeon and the south coast continue to be within reach from Southern California up to the southern-most closure point at south of Vicente Creek Bridge at post mile 25.3.
There is a 6.8-mile-wide segment of Highway 1 between the two turnaround points that remains inaccessible to through traffic due to the ongoing repair work at Regent’s Slide.
Road information and updates can also be found on Caltrans District 5 Social Media platforms: X/Twitter at: @CaltransD5, Facebook at: Caltrans Central Coast (District 5) and Instagram at: Caltrans_D5.
