OAKLAND, Calif. (CN) – The San Francisco-Oakland Bay Bridge was considered a monumental feat of civil engineering when it was completed in 1936 – but that was a long time ago.
The bridge linked San Francisco with the East Bay as millions of Americans turned to automobiles as their main mode of transportation.
Fifty-three years later, a 7.1-magnitude earthquake rocked the mammoth structure and a 50-foot section of the upper deck collapsed, killing one driver.
The eastern span had to be rebuilt, to withstand an 8.5-magnitude earthquake, using modern techniques and the highest standards in civil engineering.
But reconstruction was dogged by delays, cost overruns, materials unacceptable by state standards and other problems, which transportation officials are still struggling to resolve.
When it was completed in 2013, the $6.5-billion eastern span was $5 billion more expensive than planned and six years behind schedule.
Critics say the pressure to contain costs and meet deadlines brought poor management choices that will continue to cost taxpayers and toll-payers, who must foot the bill to fix the unanticipated invasion of corrosive saltwater inside the structure.
Other problems include cracks in the foundation, missing sections of deck drainage that allow rainwater to bleed inside the structure, and saltwater seeping into shafts around anchor rods, which provide extra support in an earthquake.
The three-member panel tasked with overseeing the bridge’s eastern span wants to claw back $24 million from three contractors found responsible for the failure of seismic stabilization rods.
The panel voted in September to end its contract with the eastern span’s main contractor, the joint venture American Bridge/Fluor, and to demand repayment of $8 million for the failing rods, $1.5 million for delays and $3 million for incorrectly installed anchor rod grout.
The panel also wants to reclaim $8 million from the contractor TY Lin/Moffett & Nichol for the failing rods, but during a Thursday meeting, the bridge’s Panel Oversight Committee suggested that dispute may have to be settled through arbitration.
Panel member Malcolm Dougherty negotiating a resolution that would include TY Lin/Moffet providing at-cost consulting and engineering services to settle claims over the unacceptable rods.
Bay Bridge chief engineer Brian Maroney said that even without those 424 anchor rods, the bridge’s new eastern span could ride out an earthquake with minimal impact.
“We identified that these rods are not critical,” Maroney said. “They only serve to transfer or carry loads in a very large earthquake. Even if magically all the rods were gone, you’d still be able to function as a lifeline route.”
Maroney said he based that conclusion on a “conservative” test by a computerized model that incorporated assumptions about the bridge’s design.
He said analysts are sifting through construction records, sampling steel and taking into account as-built conditions to generate a more accurate picture of how the eastern span would perform in an earthquake without the rods.
Despite those reassurances, one engineering expert said bridge managers are downplaying the importance of the anchor rods.
“The idea that these hold-downs are not necessary because the tower weighs so much is preposterous on its face,” said Bernard Cuzzillo, a mechanical engineer with the Berkeley Research Company. “The tower’s weight is small compared to the weight of the earth that’s moving under it.”
Another issue is the large cracks that surfaced in the eastern span’s concrete foundation in 2007.
Maroney said that “all concrete cracks,” and that some cracking was expected. He said when the cracks were discovered, they were sealed with high-grade epoxy to minimize saltwater infiltration.
“There are going to always be some cracks,” Maroney said. “There will be some water that gets into concrete. In this case, it will always make it into the steel.”
One proposal suggested using a cathodic protection system to detect and counteract corrosion by transferring the corrosive effect from a base metal to a “sacrificial” piece of metal.
Maroney told the panel not to spend extra money on that system. He said the current strategy of using data to anticipate corrosion levels and verifying the corrosion rate by testing extra pieces of steel hanging in the Bay near the eastern span every five years is sufficient.
“You’re verifying the corrosion rates are similar to what was measured elsewhere in the Bay,” Maroney said.
After a presentation on cathodic protection systems during the oversight panel’s Thursday meeting, panel chairman Steve Heminger said he wants to explore that system.
Maroney cautioned against it, saying the current method for measuring corrosion rates is adequate, less costly and does not depend on the ebbs and flows of economic cycles that can result in cuts to maintenance budgets.
The chief engineer said the bridge was designed with extra layers of steel to address the anticipated level of corrosion. The design was based on known corrosion rates that affect other structures in the Bay, including the San Rafael-Richmond Bridge, where the water is more oxygen-rich and the steel corrodes more easily, Maroney said.
“What I pushed for and designed was a system where we took measurements on Bay Area bridges, and we have corrosion rate records for research,” Maroney said. “That means down the road people of California don’t have to keep paying taxes and tolls, and if times are bad, that extra steel is there.”
But Heminger responded that several unanticipated issues – including cracks in the foundation and saltwater intrusion – make adding an extra level of protection worth exploring.
“The structure has water inside it, too,” Heminger said. “It seems we have a different condition than the design.”
Caltrans Deputy Director Stephen Maller reminded Heminger that the experts assigned to advise the panel recommended against using a cathodic protection system.
“Experts give us advice, but they don’t make decisions,” Heminger said. “We make decisions.”
The chairman asked that more information be presented at the panel’s next meeting in February, on how cathodic protection has been used on other Bay Area bridges, including the San Rafael-Richmond Bridge and Dumbarton Bridge.
Maroney said he also expects to offer more information on the tower anchor rods investigation at the next meeting, including results of a new test on how the eastern span would survive a quake with as-built conditions, without the rods.
The chief engineer said he anticipates final recommendations will be made by next summer on replacing “questionable grout” around the rods where water has seeped in.
Asked if regrouting work could result in higher tolls for drivers, Maroney said he expects the regrouting will cost about $10 million, which should not affect toll rates.
Despite the mounting criticism over the troubled construction process and safety concerns, Maroney said the bridge is safe and that no major construction project is ever perfect.
“Overwhelmingly, it’s a fantastic bridge,” Maroney said. “Was everything done perfectly in construction? Absolutely not.”
The chief engineer said that sometimes when problems were discovered it was not in the best interest of the taxpayers to “rip it out and do it all over again.” He said engineers have thoroughly investigated the issues, and in some cases the state has tried to recapture money from contractors who did not perform their work adequately.
“Were there imperfections there? Were there misses?” Maroney said. “Absolutely, like on every job, but we had engineers inspecting, and we investigated the issues.”
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