In some places the snow on the roads is so deep that the snowblowers can't cut through it.
So they shave the mass from the top to make it manageable for the blowers.
From the California Department of Transportation, first up, May 25:
And a demonstration of the technique from May 11:Maintenance crews on Sonora Pass (State Route 108) have made progress over the past five days, but this snow is putting up quite the battle.
— Caltrans District 9 (@Caltrans9) May 25, 2023
Before you travel this spring, be sure to check out https://t.co/E2g76i5kLV or download the #Quickmap app to your iOS or Android device. pic.twitter.com/lCD3BlBFIV
Because the snow over Sonora Pass is so deep, @Caltrans9 maintenance crews are using a snow cat to push the snow from above to the road below where the snow blowers can clear it from the highway. This method reduces the snow depth, allowing the snow blowers to push through. pic.twitter.com/wfVNR65TLx
— Caltrans District 9 (@Caltrans9) May 11, 2023
The road is due east of San Francisco and rises to 9600 feet at the Pass.