Commentary: Bad Bay Bridge Bolts Won’t Stop Work Toward Seismic Safety
By Steve Heminger, executive director of the Bay Area Toll Authority
The recent discovery of broken bolts on the new east span of the San Francisco-Oakland Bay Bridge has understandably shaken public confidence in this world-class structure. The sole purpose of the retrofit project is to move traffic from the seismically deficient old span to a sturdier crossing capable of riding out multiple large earthquakes over the next 150 years. It’s frustrating that after years of engineering innovation and difficult construction work, we face the possibility of further delay. But the job at hand — building a bridge that carries everyone safely into the future — has not been stopped before by adversity.
After 32 bolts broke on one of the bridge piers in March, the Toll Bridge Program Oversight Committee — created by state law to oversee seismic improvements to the Bay Area’s toll bridges — launched an aggressive investigation. We challenged Caltrans and its contractors to divulge records and testify publicly about what we know and what we still need to learn. When our report is complete, it will be subject to a rigorous, independent review. Californians will get a fix they can depend on.
In 2005, when the Legislature funded the final leg of the seismic retrofit program, it created our oversight board to improve accountability, ensure openness and exercise leadership in the face of construction challenges. We take this job seriously. The California Transportation Commission, Caltrans and the Bay Area Toll Authority have joined forces to dig through thousands of pages of construction records, consult experts from around the world and put engineers to work designing a retrofit solution to the broken bolts.
It’s important to remember why we are building a new bridge. On Oct. 17, 1989, the Loma Prieta earthquake collapsed a 50-foot, 250-ton section of the upper deck of the Bay Bridge, resulting in tragic loss of life that no one will forget. Since that day, we have never lost sight of our goal to replace the old bridge — built during the Great Depression — and move everyone onto a safer structure.
We expect Caltrans and its engineering consultants to work together with bridge contractors — setting aside questions of blame and liability for now — to solve the problem at hand. We insist their work be peer reviewed by an outside panel of experts as yet another layer of oversight and protection. In addition, we have decided to subject our findings and recommendations to an arm’s-length review by the Federal Highway Administration. I welcome this oversight from independent entities to ensure our investigation is comprehensive and our solution is the best and safest possible.
As reported at our last regular public briefing, we have concluded that the anchor bolts on the pier broke because a susceptible metal was exposed to a source of hydrogen and then placed under high levels of stress — which together can make the steel so brittle it fractures.
There are numerous high-strength bolts at other locations on the new bridge and that is why engineers are carefully and methodically investigating those locations as well. These other bolts remain intact and preliminary test results show some differences in the manufacturing process — they were fabricated two years apart — and in the metallurgic composition from the bolts that broke. But this committee is not taking any chances. It has ordered extra tests be done before it will decide whether to replace any bolts that have not broken. This week we will provide updated information from investigators about the status of these tests before clearing any bolts for permanent use.
When the bridge opens to traffic, it will be safe. I write this with confidence, not only because I chair the oversight committee that is leading this investigation, but also because my colleagues and loved ones will drive across the new span every day. Safety is not Job One on this project — it’s the only job.
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