Bay Bridge opening still unclear because of broken bolts
04/11/2013 12:00 AM
04/12/2014 7:26 PM
Transportation officials said Wednesday that they still do not know whether the new Bay Bridge will open as scheduled, or how they will solve the problem of broken bolts that were used despite having failed some quality tests.
Both developments were revealed at an Oakland meeting of the Metropolitan Transportation Commission, where Steve Heminger, executive director of the commission, said deciding on the projected opening of the new Bay Bridge might take weeks or months.
He and other transportation officials said they hope the projected Labor Day opening will still be possible, but that depends on how fast an engineering work-around can be selected, approved and built.
"Until we have a solution, we don't know what our schedule is," Heminger said.
He also disputed the $1 million cost estimate for the work, earlier provided by Toll Bridge Program Manager Tony Anziano.
"We don't know what the solution is, so we don't know what it costs, either," Heminger said. "We don't know schedule, we don't know budget."
A few options are being considered, including metal collars that would fit over two seismic shear keys to replace the function of the broken bolts, and a steel-reinforced concrete cover.
The bolts, designed to secure vital seismic safety equipment for the suspension span, failed last month when they were stressed, or placed under tension, to increase overall performance.
Agency engineers had permitted the bolts to be installed despite having failed five of 150 quality tests conducted by the manufacturer and the Caltrans materials lab, Anziano said at the meeting. The failed tests involved elongation of the bolts. The Bee has requested copies of the testing documents, but Caltrans officials have not yet made them available.
Kevin Garrity, past president of NACE International, a global training and standards group for corrosion-control issues, said accepting bolts that failed tests seemed unusual, and probably would have required an engineering assessment that the parts would function as required and not affect the service life of the bridge.
"Even then, you'd have to look at it very carefully and cautiously before moving in that direction," he said in an interview with The Bee.
Anziano said that a range of other parts manufactured by Dyson Corp. of Ohio, the bolts' supplier, have been visually examined, and so far show no defects. A review of those parts, some of them in place on the bridge tower, will continue.
Any solution to secure the shear keys will take months to design, approve and install.
Oakland Mayor Jean Quan asked Heminger whether setting a "drop dead date" for confirming the Labor Day opening would be prudent to avoid a huge loss of hotel revenue for guests arriving for the event, as well as costly, last-minute disruptions to celebration plans.
Heminger agreed that such a decision might be made eventually. The timing, he said, depends largely on how long fabricating new parts would take.
Officials emphasized that public safety is the primary consideration for the $6.4 billion bridge.
"Caltrans owes it to the commuters to deliver a safe bridge," State Sen. Mark DeSaulnier, D-Concord, chairman of the Transportation and Housing Committee, said in a written statement. "Caltrans needs to take the time necessary, and not cut corners, to get the bolt problem fixed."
He said the department needs to deliver critical information openly and in a timely fashion.
Anziano said the agency remains hopeful that only the 96 suspect anchor bolts, also called rods, installed in 2008 on two of the four shear keys, will require the planned fix. Of those bolts, 32 had snapped. The remaining 192 bolts, installed in 2010 to secure two other shear keys and four giant seismic bearings, so far have shown no signs of breakage after having been tightened. But they have yet to be tested fully.
Caltrans is still trying to determine why the 3-inch diameter bolts broke, but suspects that contamination by hydrogen caused them to become brittle. This could have been caused by a manufacturing problem or by water leaking onto the bolts after their installation – even though the bolts had by then been embedded in concrete.
Garrity, who is an executive with Ohio-based Mears Group, Inc., a global construction firm that specializes in corrosion issues, concurred that hydrogen contamination can occur at several points in the process, before or after installation. He said Caltrans forensic tests should be able to determine if the steel had been contaminated with other substances that sometimes interact with hydrogen in ways that can lead to "stress cracking."
Responsibility for the problem – including who will bear the cost of corrections – will be assessed later, Heminger said.
Call The Bee's Charles Piller, (916) 321-1113. Follow him on Twitter @cpiller.
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