SAN FRANCISCO (KRON) – Corrosion in the Oakland-San Francisco Bay Bridge’s Yerba Buena Island tunnel that caused a concrete chunk to break loose last month and narrowly miss a motorist is more widespread than the state first believed.
And crews are scrambling to fix the problem. This issue came to light late last month, but now, a new Caltrans survey of the tunnel reveals more wide-spread damage that could prompt more concrete to crumble onto lanes of traffic.
On Jan. 30th, a tire size piece of concrete broke free, falling onto the lower deck of traffic and barely missing a driver. Now, Caltrans said it has found 12 spots where concrete could break off from the tunnel’s walls.
Water and corrosion have caused the compromised concrete. The problem is on both sides of the tunnel.
“Yeah, I watched it [concrete] totally fall from the…wall area and it just like boomed down very abruptly,” driver Liz Gustin said.
Liz swerved to avoid it, but she said the concrete scraped the side of her car and punctured the back tire.
Following that incident, Caltrans inspected the tunnel. By tapping on the walls and ceiling with a hammer, they were able to identify a dozen places where the concrete was in danger of falling.
They have since repaired those spots and now say the tunnel is safe.
Caltrans has launched an investigation to figure out why the concrete failed in the first place.
The tunnel was built in the 1930s and retrofitted in the 70s, so age could be a factor.
They also said that water could be seeping into the concrete causing problems, but they don’t yet know for sure.