A Bridge Too Weak?

A UC Berkeley professor believes the unique new Bay Bridge design is fatally flawed

Herb Rothman, the bridge's chief design engineer, discounts that scenario. "This bridge will be very well suited to a high seismic area," says Rothman, 79, whose professional credits include having been project engineer during construction of New York's Verrazano-Narrows Bridge in the 1960s. "As far as we're concerned, the bridge has ideal earthquake characteristics, and meets all the standards that the state mandated for it."

Although a few smaller self-anchoring spans using two towers have been built in the last 20 years, including one in Japan and another in South Korea, the Bay Bridge crossing will be by far the world's longest self-anchored structure borne by a single tower. As a result, Astaneh notes, there are no seismic performance data available for this type of bridge. "If they build this bridge and the Hayward fault ruptures, there is a high probability that the resulting earthquake would severely damage the bridge, and possibly cause a partial or catastrophic failure of the main span," he says.

Astaneh shared his concerns with MTC officials before the advisory panel approved the design in 1998. He did so again in 1999 after then-San Francisco Mayor Willie Brown, with help from the Navy, succeeded in delaying final state and federal approvals following a brouhaha over the span's alignment across Yerba Buena Island property owned by the Navy. (The federal land has since been turned over to the city of San Francisco.) Alarmed that little was happening to replace the unsafe existing bridge more than a decade after the Loma Prieta quake, the Clinton administration intervened in 2000 to help settle the dispute.

Professor Astaneh says Caltrans cut funding to UC 
Berkeley following his criticism of the bridge design; 
Caltrans denies any retaliation.
Paolo Vescia
Professor Astaneh says Caltrans cut funding to UC Berkeley following his criticism of the bridge design; Caltrans denies any retaliation.
At 1,850 feet, the curving, self-anchored, single-tower 
suspension span will be the longest of its type in the 
At 1,850 feet, the curving, self-anchored, single-tower suspension span will be the longest of its type in the world.

After hearing a lengthy presentation from Astaneh in 1999, Brown held a news conference the next day to announce his opposition to the single-tower design, saying he was convinced it was unsafe. Although critics accused him of posturing, suggesting that Brown's agenda was to torpedo any design that might interfere with plans by politically connected friends to develop part of Yerba Buena Island, the mayor never recanted his safety concerns.

With a boost from Brown, Astaneh was dispatched to Washington, D.C., where he gained an audience with Clinton administration staffers including a high-level assistant to then-Transportation Secretary Rodney Slater. With Brown and the Navy resisting the self-anchored design on one side, and Caltrans, the MTC, and Gov. Davis pushing for the bridge project to move forward on the other, the U.S. Army Corps of Engineers was called in to study the issue.

Although the Army engineers gave their seal of approval to the bridge design, a voluminous Corps report issued in October 2000 can hardly be classified as a ringing endorsement. About the best the engineers could say about the seismic concerns Astaneh had raised was that "the design team is moving along a path to design a bridge that meets the seismic performance criteria" established by the MTC.

The Army Corps concluded that the bridge was not designed for a "maximum credible earthquake," or MCE, along either of the two nearby fault lines. An MCE denotes the most severe ground motion considered possible at a given location. Scientists say the San Andreas fault, which runs beneath the peninsula on which San Francisco rests, is capable of producing an MCE of 8.0 on the Richter scale, and that the Hayward fault, which passes beneath the Oakland hills within five miles of the bridge, could produce a 7.25 shaker. By comparison, the Loma Prieta quake, which, among other things, collapsed the Cypress Freeway in West Oakland, killing 42 people, and killed another person on the Bay Bridge, measured 7.1. But its epicenter was 60 miles south of the bridge; experts say damage to the span would have been worse had the epicenter been closer.

Caltrans and the new Bay Bridge's designers say their plan incorporates the highest seismic safeguards. But they based their calculations on a different model, called the "safety evaluation earthquake." SEE places more emphasis on the probability of a major quake occurring during the bridge's anticipated 150-year life span.

The Army engineers didn't take a position on which is the better approach. Neither did they pass judgment on the self-anchored bridge's seismic characteristics compared to other designs.

"On a scale of A to F weighing seismic safety reliability and cost efficiency, where A is the best system and F is unacceptable, how would you rate the standard anchored suspension bridge and the proposed self-anchored, asymmetric single tower, pile-supported East Span replacement?" reads a question posed in an appendix to the Army Corps report. The engineers' response: "The rating requested in this question is outside the current scope of work."

The MTC board voted 11-1 in favor of the self-anchored design recommended by its advisory panel. Then-Oakland Mayor Elihu Harris was the lone dissenter, at the time citing cost and aesthetics as his primary objections. His successor, Jerry Brown, took a similar position. Looking back, Harris now says, "I think [the MTC] was too eager to get on with it. And it was too dismissive of Astaneh."

Although his expertise remains highly sought-after by others, Astaneh says he has paid a price as the bridge's chief naysayer.

After he spoke out, Caltrans halted payments on a $500,000 grant to the university's engineering department for work being done under Astaneh's supervision. "Caltrans is not good at tolerating dissent," he says. Caltrans denies any retaliation, saying budget cuts forced it to scale back spending for academic research.

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