New Problem With Bay Bridge Span Could Pose Danger in Quake
The Bay Area has gone four weeks without a disclosure of problems on the new eastern span of the Bay Bridge. The San Francisco Chronicle’s Jaxon Van Derbeken is among those ending the revelation drought with a story on a potentially major problem with rods that anchor the spans’s main cable. (The Sacramento Bee’s Charles Piller reported on the issue on Thursday.) Here’s the top of Van Derbeken’s piece:
Steel rods that anchor the Bay Bridge eastern span’s massive main cable have shifted since they were installed and are now perilously close to sharp-edged plates inside the belly of the new bridge, a problem Caltrans acknowledges could take months and millions of dollars to fix. Caltrans engineers say more than 200 high-strength rods could be jerked in a major earthquake into those sharp edges, risking damage to the main cable and possibly threatening the bridge’s stability. “We need to do whatever we need to do so this does not happen,” Brian Maroney, Caltrans’ chief engineer on the bridge, said Thursday.
Let’s step back from the bad news for a second and say: That new span sure is beautiful. And it gives you the perfect vantage point to watch crews dismantle the old eastern span, which except for 17 horrifying seconds in 1989, spared its hundreds of thousands of daily users much drama. The new span, by contrast, is full of suspense. Even before it opened, it was delivering surprises: The massive rods designed to anchor seismic-stability devices cracked, leading to months of questions about the steel used in the bridge and a scramble to find a fix. Some of the steel tendons designed to strengthen the bridge’s long concrete skyway were found to be inadequately protected from the weather. After the bridge opened in September, engineers discovered that supposedly watertight support structures beneath the suspension span’s road deck were leaking, posing a serious corrosion threat. And now, issues with the rods anchoring the cables.
It used to be that when I saw work crews on the bridge, I’d think, “You know, Caltrans does a great job keeping up with the maintenance on this fine old bridge.” When I see workers on the new span these days, I wonder, “What’s wrong now?” In his story, Van Derbeken says the steel rods anchoring the cable have shifted because of a seemingly innocuous decision made during construction: to enlarge a single cable-anchor hole. Caltrans engineers and local transportation officials are optimistic they’ll be able to deal with the problem fairly quickly, although the Bee’s Piller quotes one expert as saying that making the fixes could be very challenging. Van Derbeken’s piece ends on a disquieting note:
Bob Bea, an emeritus professor of civil engineering at UC Berkeley and risk analysis expert, said the latest snafu was a “predictable surprise” because of the builder’s decision to make one hole bigger than the others. “It’s something that you could have predicted if you thought more about it, but you didn’t think deeply about it,” he said. “It’s easy for these damn details to sneak through the design process – that’s what seems to be going on here. I wonder what other things are lurking in the darkness.”