Every year since 2001, about 700 truckloads of fallen rock have been transported from the Pitkins Curve/Rain Rocks area just north of Limekiln State Park (at a cost of about $1,000,000 a year).
At Pitkins Curve, landsliding below the road has caused collapse of the southbound lane of Highway 1 on more than one occasion. Rain Rocks experiences more rockfall from above. Both of these areas have been responsible for numerous closings of Highway 1 for months at a time.
The combined solution to these problems is the new bridge at Pitkins Curve which leads (when traveling south) directly into the Rain Rocks Rock Shed, a rock tunnel that's lets boulders fall as much as they please without cluttering up the road.
Big Sur Kate has more background info and photos on her blog.