OAKLAND -- In a quiet close to a tumultuous chapter, contractors on the new Bay Bridge on Wednesday completed the $25 million repair of those infamous broken bolts that nearly derailed the span's opening on Labor Day.
Just before noon, crews tightened the last of the 142 concrete-encased steel rope tendons inside the massive fabricated steel saddles. They replace the clamping force lost when anchor rods snapped in critical seismic stabilizers just east of the main tower.
After the tendons were adjusted to the proper tension using hydraulic jacks and their casings grouted and capped, contractors removed the temporary steel shims inserted into the stabilizers last summer to make the bridge safe enough to open during repairs.
While the embarrassing bolt repair chapter may be over, the book on the Bay Bridge is far from finished, with hearings scheduled in Sacramento early next year into why the span was a decade late and cost nearly fivefold what engineers estimated.
Wednesday's announcement comes three weeks after engineers originally estimated the work would be done but several weeks ahead of Caltrans' latest schedule.
Completion means the $6.4 billion span's structural protections against collapse or major damage in the next big earthquake are fully operational, said Caltrans field engineer Pamela Gagnier during a Tuesday boat trip out to the pier where the repairs were done.
Engineers designed the bridge to meet California's most stringent seismic standard: Remain open or reopen within hours following the strongest temblor engineers predict in the next 1,500 years.
But when contractors pulled out the shims, motorists didn't feel or see a thing.
The stabilizers are located out of sight beneath the bridge deck, and the shim removal took place without traffic disruption.
American-Bridge Fluor, the contractor, will finish painting, touching up the concrete and stripping away the scaffolding in coming weeks.
Then, the only physical evidence of the fix will be the two concrete blisters on the pier's exterior that house the saddles and tendons.
Meanwhile, Senate Transportation and Housing Committee Chairman Mark DeSaulnier, D-Concord, is planning at least two Bay Bridge investigatory hearings that will also feature findings of a resurrected independent seven-member panel.
"I want to find out the absolute truth of what went on," DeSaulnier said. "I want to know, 'How safe is that new bridge?' and 'Did we get what we paid for?' And when we have answers, I'd like to bring specific corrective legislation forward this year."
Led by Georgia Institute of Technology engineering school Chairman Reginald DesRoches, the panel was temporarily derailed when members worried they would be sued over their conclusions. But the legal questions have been resolved, and the panel has resumed its look into allegations raised by the Sacramento Bee of faulty testing of concrete in the span's main tower foundation.
It will also examine what led to the installation of the defective anchor rods that snapped in March and whether other fasteners might be vulnerable.
In addition, UC Berkeley civil and environmental engineering professor William Ibbs has volunteered to convene an expert team to analyze some of the highly technical metallurgical questions raised by critics, including retired engineer Yun Chung of Alameda.
Caltrans, Bay Area Toll Authority, federal and other outside experts found no evidence to support concerns about the foundation concrete's structural integrity and say it is completely safe.
On the bolts, bridge officials say ongoing tests have revealed no evidence of weakness in the span's remaining 2,214 high-strength steel fasteners.
Experts hired to study the failure of the original 32 anchor rods blamed hydrogen embrittlement, a phenomenon where hydrogen atoms infiltrate the spaces between steel molecules and leave it vulnerable to cracking.
Caltrans has already ordered additional protections for some of the other bolts such as dehumidifiers.
But testing will continue through mid-2014, and engineers will finalize a long-term maintenance program next year, bridge spokesman Andrew Gordon said.