San Mateo County, California Bridges: Sierra Point Overhead over Caltrain Tracks (1)

August 1991 (37.674219 Degrees, -122.389354 Degrees) Sierra Point Overhead

The Sierra Point Overhead was the first bridge to be seismically isolated in the United States. It's a 10-span steel girder bridge built in 1957 and carrying State Route 101. The bridge is on such a high skew that the floor beams sit on pile extensions and the abutments. The columns (on spread footings) were not designed for strong earthquakes (it's 10 miles from the San Andreas Fault) and so it was retrofitted in 1985 with lead rubber bearings to reduce the inertia force to the substructure.

San Mateo County, California Bridges: Sierra Point Overhead over Caltrain Tracks (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.