OAKLAND -- A trio of experts on Wednesday urged Bay Bridge leaders to open the seismically safer new span on Labor Day as previously planned -- if not sooner -- and offered a temporary workaround to the broken bolts that won't be repaired until at least December.

"The contractor has the plans and it can be done in a month," Toll Bridge Seismic Safety Peer Review Panel Chairman Frieder Seible told the Bay Area Toll Authority, a panel of local elected officials who oversee bridge toll receipts. "We don't have to wait until December. We don't know when the next earthquake could happen. We have to assume it can happen any day."

The news shook the packed meeting room, where federal, state and regional transportation leaders met in the latest briefing about the catastrophic failure in March of large anchor rods in seismic stabilizers called shear keys on the pier east of the main span tower.

The Toll Bridge Program Oversight Committee had announced Monday that rod repairs, which involve installing a steel saddle to handle the heavy load of the bridge, would take much longer than originally expected, and the panel canceled the much-anticipated Sept. 3 opening to traffic and the Labor Day celebration. No substitute opening date has been set.

It is the latest twist in the project to build a $6.4 billion bridge, which is 10 years behind schedule and costing taxpayers five times more than engineers estimated.

Until the new span opens, 280,000 vehicles a day cross the existing 77-year-old span, which nearly every engineer and seismic expert who has examined it says will collapse in even a moderate earthquake.

In offering a speedier solution, Seible, a former UC San Diego engineering school chairman, revived one of the many retrofit options engineers reviewed after the bolts snapped four months ago -- inserting wedges, or shims, into the adjacent large bearings and shifting any possible forces generated during an earthquake away from the vulnerable shear keys.

Seible was flanked by his two peer review panel colleagues, John Fisher of Pennsylvania and UC Davis Professor Emeritus Ed Idriss. All are members of the National Academy of Engineering

Engineers had earlier rejected the idea because it was only a temporary fix.

"It never hurts to have a Plan B," said Steve Heminger, Bay Area Toll Authority executive director and one of three members of the oversight committee. "It merits further vetting."

While Seible has publicly opposed delaying the bridge opening on seismic safety grounds, the renowned engineer's pitch for temporary shims on Wednesday apparently came as a surprise to Heminger, Caltrans Director Malcolm Dougherty and California Transportation Commission Executive Director Andre Boutros. The three men serve as the Toll Bridge Oversight Committee and jointly manage the new span construction project.

In interviews after the 2¿1/2 hour meeting, Heminger and Dougherty appeared lukewarm to the idea. It warrants further study, they reiterated, but the required analysis could take as long as the retrofit already under construction.

They couldn't give a timeline for when the shim idea will be fully examined, but Heminger said, "It's not like we're going to dawdle."

Meanwhile, Vince Mammano, California division administrator for the Federal Highway Administration, on Wednesday blessed the bridge team's analysis of the broken rods and retrofit plan, and its strategy to replace or monitor the other 2,210 high-strength steel bolts on the self-anchored suspension bridge made out of the same type and grade of steel.

American Bridge/Fluor Enterprises, the suspension span contractor, is working with Vallejo and Alabama steel fabricators on the steel saddle and cable assembly that crews will install on the exterior of the shear keys where 32 out of 96 anchor rods broke. The cable system will take the loads originally intended for the rods.

Heminger also revealed that the Toll Authority is filing a financial claim against T.Y. Lin/Moffatt & Nichol, the private engineering joint venture hired in 1998 to design the bridge, to recover costs for the shear key retrofit.

The oversight committee released a 102-page report this week that blamed Caltrans and the engineering consortium for a series of missteps and errors related to the shear key design, steel selection, incompatible corrosion protection methods, inadequate standards and insufficient testing that ultimately led to the failures.

Additionally, Heminger said, American Bridge/Fluor Enterprises has been asked to help pay the estimated $10 million to $20 million retrofit cost, as its workers failed to protect the rods from weather damage during construction.

The exposure may have contributed to the bolts' failure, which metallurgists blame on a well-known phenomenon in which hydrogen atoms invade the latticed molecules in high-strength steel under tremendous loads and leave it brittle and vulnerable to cracking.

After the bridge opens, Caltrans will slowly replace 740 rods used in bearings and shear keys adjacent to those that contained the defective bolts. Unlike the other shear keys, where there isn't enough room to remove the very large rods -- 3 inches in diameter and 17 to 24 feet long -- these are replaceable. Testing shows the fasteners may be susceptible to long-term stress corrosion, a different type of failure found in high-strength steels, the authority was told.

In addition, crews will reduce the tension on 557 other bolts and beef up the dehumidifiers in the bottom of the 525-foot main span tower. Moisture is a source of hydrogen and the greater the tension, the higher the bolts' vulnerability for embrittlement.

Reporter Mike Rosenberg contributed to this story. Contact Lisa Vorderbrueggen at 925-945-4773, lvorderbrueggen@bayareanewsgroup.com or Twitter.com/lvorderbrueggen.