Update: Fix Of Bay Bridge May Cost $3 Million
As California transportation officials vow to increase frequency of inspections on the troubled San Francisco-Oakland Bay Bridge, they had no firm estimate of when federal inspectors would okay its reopening to traffic. For the second time in two months, crews have worked non-stop to install an emergency eyebar repair on the critical crossing, which usually carries 280,000 daily vehicles. The original fix made over Labor Day weekend consisted of a steel saddle brace wrapping around a broken beam of the steel truss. That brace snapped during the windy Oct. 27 evening commute, dropping a 5,000-lb crossbeam and steel connectors into traffic. No one was injured and the bridge is closed indefinitely.
As of the morning of Oct. 30, crews with North Highlands, Calif.-based MCM Construction Inc. were replacing all four support rods, installing damping devices to keep the new ones in place, and gouging out connecting welds, deepening them to structural welds. MCM is also adding straps to further support the four tie bars. The new design enhancements are based on the theory that vibrations from high winds caused the failure, and will focus on reducing vibration and therefore fatigue, says Caltrans spokesman Bart Ney. “Tying off the rods will ensure that if there is a failure, pieces won’t fall down,” Ney adds. Metallurgists are currently testing the damaged pieces to determine if the failure was due to design, material quality or installation.
Tensioning the rods was expected to take about three hours. The replacement pieces were fabricated in Sacramento and trucked to the site. Crews have been dealing with high wind gusts of up to 50 mph as they worked carefully to remove debris and put the new steel in place, according to Ed Puchi, MCM Construction treasurer. Ney says the cost of the original fix was less than $2 million and came from emergency funds. The current project will probably be similar, he says.
MCM was working on an unrelated contract to build the Oakland touchdown portion of the reconstruction. Puchi says his engineer happened to be on his way home near the scene of the failure when it occurred. Caltrans asked him to mobilize the MCM crew and cranes. Within hours, they had 20 people, welding gear, inspectors and rod tensioning specialists on site.
The original fix was made after California Dept. of Transportation inspectors discovered a crack in the steel beam located in the cantilevered eastern span. They were conducting a routine inspection in conjunction with a weekend closure to install a 288-foot S-turn detour as part of the $6-billion reconstruction program. C.C. Myers, Rancho Cordova, Ca., the contractor on the detour project, surprised many by installing the brace in a separate emergency contract and reopening the bridge with only a 90-minute delay. However, federal inspectors never checked those repairs.
Caltrans inspectors did continue to monitor the fix, and did not some vibration on the support bars about 10 days before the Oct. 27 incident, said Dale Bonner, California secretary of Business, Transportation and Housing, at an Oct. 29 press conference. He added: “I want to stress that while a cracked eyebar can lead to catastrophic failure, we are not anywhere near that.” He said that the crack is not migrating. “We will give [federal] inspectors all the time they need to test the repairs,” he added. Engineers considered replacing the eyebar entirely, but the process would take many months, and “may not solve the problem,” he said.
Caltrans plans to increase inspections from every two years to every three months on the bridge, and will close two lanes each Saturday for inspections as well.
Dan Baker, C.C. Myers project manager, has said his company would not be fined for the failure because the design was approved by Caltrans. Ney confirms this, adding: “We are very happy with the performance of both contractors.”