Yes, the rocks fall on the highway. This week, this first tunnel built in California in 50 years opened to bypass a beautiful but very dangerous area called "Devil's Slide" near Pacifica. I was fortunate to drive it before it closed; they have plans to turn it into a park and that's going to be very cool - IF they can keep it from falling into the ocean.
No pictures from there because you just don't dare stop. This is south of Half Moon on Highway 1, just another example of the scenery you find on the drive...