Construction crews working all night have made faster-than-expected progress clearing a major rockslide that closed one of the primary routes into Yosemite National Park for more than a week.
Hundreds of tons of rocks crashed down March 17 across both lanes of state Highway 140, a scenic winding route along the Merced River between the town of Mariposa and Yosemite’s Arch Rock entrance, just as the spring travel season was beginning to ramp up.
Now one lane of the highway — which is one of the two main routes into Yosemite for most Northern Californians — will open at 4 p.m. on Wednesday, said Brian Hooker, a Caltrans spokesman.
“It’s worked out well,” Hooker said. “We recognize the impact of this road on the local economy and for park guests with travel plans, and we’ve done everything we can to open it quickly and safely.”
The slide closed about two miles of Highway 140 in both directions between Yosemite Cedar Lodge and Briceburg, 10 miles west of El Portal.
On Thursday, Caltrans geologists investigated the area and flew drones to take 3-D images of the steep cliffs above the road. They were trying to find loose boulders and other material that might still collapse onto the roadway.
Using that information, crews from a specialty contractor, Neil’s Controlled Blasting, based in Placer County, used an aerial lift to move workers up to 130 feet high on the sheer cliffs Friday and Saturday. Some workers rappelled on the cliff with ropes.
They fitted large industrial pillows, like air bags on a car, behind the suspended loose rocks, and inflated them with compressors, Hooker said, causing the unstable geology to topple onto the roadway below.
On Sunday, Teichert Construction, based in Sacramento, began using trucks, front loaders and other equipment to start hauling away the main pile blocking both lanes. They worked all night Sunday, throughout the day Monday, and all night Monday, he said, clearing all the rocks.
They have begun rebuilding the road bed and pouring new asphalt.
“The unseasonably warm weather allows for the asphalt to cure and set,” Hooker said. “It’s been a blessing for us to have this hot weather. It enabled the contractor to get the work the work done pretty expeditiously.”
After the road opens one way Wednesday afternoon, with flaggers to allow traffic to intermittently travel both directions, the one-way conditions are likely to remain for another few days while the paving is finished, shoulders are built, and the road is striped, Hooker said.
For daily updates, visitors should check Caltrans site before heading to the park: Quickmap.dot.ca.gov.
Hooker said engineers on the job believe that the recent weeks of cold weather, which dropped snow levels lower than normal, froze water that had accumulated in cracks on the cliffs. That ice expanded, causing the rockslide, he said.
The Yosemite area is no stranger to active geology. Many of the park’s main canyons and stunning rock features were carved by glaciers over millions of years. Last year, a major rockslide closed Highway 120, the other primary route for Bay Area visitors. And a huge slide on Highway 140 in 2006 forced Caltrans to build a detour bridge across the Merced River which remains to this day.
