The photos are pretty dramatic.  The rain coming off two slopes combined to erode, collapse and wash away the entire roadway.

It happened south of Monterrey in the Big Sur area.

Quoting the LA Times, "The biggest problem is a 150-foot-long chasm where the highway used to run at Rat Creek, two miles south of the Esalen Institute. That area, authorities noted, lies below the “burn scar” left by the Dolan fire, which blackened about 125,000 acres last August."

How do they fix that?

I drove down PCH from Santa Cruz to Ventura over Thanksgiving.  Beautiful drive.

They build a GIANT retaining wall and back fill the earth.

With a BIG culvert through it that can't get blocked and cause flooding over the road surface.