Metal 'shims' proposed for fixing Bay Bridge
07/10/2013 5:06 PM
04/12/2014 7:26 PM
OAKLAND – Expert consultants to the California Department of Transportation proposed a temporary retrofit for a broken-bolt problem, which – if adopted – could permit the new San Francisco-Oakland Bay Bridge span to open by Labor Day.
The proposal came on the heels of Monday's supposedly firm announcement by bridge oversight authorities that the span would open only after completion of a steel "saddle" retrofit – estimated for Dec. 10 – to replace broken bolts on the new suspension span's east pier.
Oversight officials said at a meeting of the Bay Area Toll Authority here Wednesday that they would evaluate the new retrofit plan for its engineering adequacy.
The idea emerged amid renewed questions to Caltrans from elected officials about Sacramento Bee investigations concerning corroded tendons in the new span's skyway viaduct and flawed welds in the base of its iconic tower.
State senators, who had been assured by the oversight group Monday that the bridge opening would be delayed for safety reasons until the saddle was completed, said they were surprised and disturbed by the sudden consideration of a previously unknown retrofit option.
The fix, described by Frieder Seible, an engineering professor emeritus at UC San Diego, would involve "shimming" the span's massive seismic bearings with steel plates in what Seible called "a very simple structural operation" that has already been designed.
This would provide "full seismic safety," Seible said. "We can achieve that seismic safety within a month's time."
Steve Heminger, executive director of the Metropolitan Transportation Commission and chairman of the oversight group, expressed caution about adopting a new seismic solution "somewhat on the fly," but said the shim idea would immediately be assessed "so that we can develop scope, schedule and budget."
"It never hurts to have a 'plan B.' I do believe this idea merits further vetting," Heminger said, holding out the prospect of a Labor Day opening if the idea passes engineering muster.
Heminger chairs the Toll Bridge Program Oversight Committee, which includes the heads of Caltrans and the California Transportation Commission.
Randy Rentschler, legislation and public affairs director for the Metropolitan Transportation Commission, said in an email that bridge authorities have no drawings for the shim idea and could provide no information about when or by whom it would be evaluated. Until now, officials have said that July 10 was the latest date that a decision to open on Labor Day could be made and still allow necessary planning. Rentschler could provide no information about whether that estimate also had changed.
"I'm a little concerned about a $6 billion bridge being shimmed," said state Sen. Anthony Cannella, R-Ceres, in an interview.
Cannella, a civil engineer and member of the Transportation and Housing Committee, expressed alarm about a sudden reversal of Monday's "firm decision."
"To change course this dramatically, I think the public is going to be skeptical and concerned," he said. "I'm skeptical and concerned."
Sen. Mark DeSaulnier, D-Concord, who chairs the Transportation and Housing Committee and has been involved with the new span for many years, called the abrupt change "disconcerting to say the least."
"It's a symptom of the management of this project – and it's not a good symptom," DeSaulnier said in an interview. "This is part of the reason why the bridge is billions over budget and years late. The governing structure of the bridge has been a problem from the beginning. The (oversight group) was supposed to be the solution, but it also doesn't seem to be functioning so well."
Heminger and Caltrans Director Malcolm Dougherty recounted the series of mistakes that were detailed in a report released Monday. The errors led to the broken bolts and to plans to replace hundreds of others that were used despite their unsuitability in a marine environment.
Bridge contractors and Caltrans shared in failures to adapt bolt requirements to Bay Bridge conditions and to seal some bolts against the elements – a factor that could have contributed to their breaking. Dougherty also acknowledged that Caltrans could not locate some quality assurance records.
"Frankly, it sounds like the mother of all construction claims," said Dave Cortese, commission vice chairman and a Santa Clara County supervisor. "How do we as (commissioners) ensure that people feel that they're getting what they bargained for and not paying for the mistakes of others?"
Heminger said contractors have been asked about "chipping in for the cost of the retrofit," and that a claim will be filed against the bridge designer's insurer.
Heminger and Dougherty said that despite the missteps, the bridge will be safe once a retrofit is completed. Vincent Mammano, administrator of the Sacramento office of the Federal Highway Administration, said his agency concurred, but he conceded that it has not closely reviewed the saddle retrofit or shim ideas.
Toll commissioner and Oakland Mayor Jean Quan pressed Dougherty to address lingering doubts about the skyway tendons. She cited a Bee investigation published in May, in which experts criticized Caltrans for using incorrect tests to prove that tendon corrosion was minor. The story also showed that Caltrans failed to stop the intrusion of water that caused the corrosion even after those tests were conducted.
"Quite frankly, since we now have extra time I'd like to see actually a point-by-point response to the tendons issues," Quan said.
Dougherty said the problem had been "thoroughly evaluated" but that he would be willing to address the issues cited in The Bee report.
Quan and other officials urged that certain UC Berkeley professors who have criticized the agency's practices should participate in peer review for the new span – a view shared by some state senators. Conflicts of interest among the current peer review panelists undermine public confidence, and the new span should be able to stand up to the scrutiny of qualified skeptics, Cannella said.
In a written statement obtained by The Bee, UC Berkeley metallurgist Thomas Devine said he has told Caltrans the "the three major problems of the Bay Bridge" – the bolts, skyway tendons and faulty welds at the base of the tower – "collectively indicate the lack of metallurgical input into the selection and deployment of steel at key locations in the bridge."
DeSaulnier recently introduced legislation that would formalize and expand the role of a panel formed by the Legislative Analyst's Office to examine possible deficiencies in the tower's foundation.
Call The Bee's Charles Piller, (916) 321-1113. Follow him on Twitter @cpiller.
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