San Francisco County, California Bridges: Fourth Street Bridge across China Basin

July 2014 (37.77495 Degrees, -122.39230 Degrees) Fourth Street Bridge

The Fourth Street (Peter R. Maloney) Bridge (34C0027) is just a block away from yesterday's bridge. It was originally a heel trunnion bascule bridge similar to it's neighbor. However, after the 1989 Loma Prieta Earthquake they removed the 1.4 million pound counterweight above the bridge and replaced it with a mainly decorative 100,000 pound weight. A new counterweight was then placed in a pit under the road to raise and lower the bridge. 

During the next earthquake, the much lighter, decorative weight can be securely supported without damaging the bridge while the new counterweight is prevented from moving. This bridge was built in 1917 and retrofitted between 2003 and 2006.

San Francisco County, California Bridges: Fourth Street Bridge across China Basin by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.