The unsettling truth is that the Golden Gate Bridge is the only bridge in California that has not been seismically retrofitted, but officials are finally starting that process, which is likely to take years and go wildly over budget.
We’d normally call this a “fun fact,” except it is more terrifying than fun. The Golden Gate Bridge is the only bridge in California that’s not seismically retrofitted, as we explained in a 2017 report. It is now six years later, and that fact remains largely unchanged.
But it may relieve bridge drivers, walkers, and runners that, as the Bay Area News Group reports, the Golden Gate Bridge’s massive seismic retrofit project is finally getting started. The Golden Gate Bridge, Highway and Transportation District that manages the structure is planning to sturdy up the bridge so that it can withstand an 8.0 magnitude earthquake, which is roughly the magnitude of the 1906 earthquake.
While the Golden Gate Bridge was not damaged in the 1989 Loma Prieta earthquake, that was probably just sheer luck of distance from the epicenter. The upper deck of the Bay Bridge did collapse onto the lower deck, which miraculously only resulted in one death. The main suspension span of the bridge could theoretically collapse in an 8.0 quake, so yeah, it’s probably time to address that.
“For us, we really are going through one of the most important undertakings on this bridge,” district engineer Ewa Bauer-Furbush told the News Group. “That’s the project for us.”
It’s not as if the district has done nothing. As seen above, this a three-phase project, and first two phases are already completed. We’ve retrofitted the two viaducts on the San Francisco and Marin County sides of the bridge.
But those are the easy parts. The hard part is the suspension span that has no viaduct support, and will require separate retrofitting of the two towers, the cables, the floor beams, the tower struts, and more.
Officials are hopeful they can do this with just some lane closures, and not a full closure of the bridge at any point. But the project is pegged at $880 million, and we know from recent experience that Golden Gate Bridge project costs tend to skyrocket out of control. And per the News Group, only “about $451 million of the $880 million” cost has been lined up.
Plus, they don’t have a contractor selected yet. That’s not expected until late 2024 or early 2025 (and remember, these contractors will sometimes sue the bridge district, which does not speed things up). And they’re not even hazarding to guess when the real construction will begin. So we’re basically reduced to hoping that the Big One does not hit while all this red tape, planning, and construction sorts itself out.
Image: Joonyeop Baek via Unsplash