Smarting from a second emergency closure of the Oakland-San Francisco Bay Bridge in two months, the California Dept. of Transportation is exploring long-term repairs for a cracked eyebeam until the crossing’s $6.3-billion modernization is completed in 2013.
Caltrans engineers are considering replacing part or all of the truss system that has a cracked eyebeam, discovered by inspectors on the 73-year-old cantilevered eastern span during a Labor Day closure. Rancho Cordova, Calif.-based C.C. Myers Inc. was installing a 288-ft detour ramp as part of the reconstruction when inspectors found the 1½ in. crack in a 2-in.-thick, chain-like steel beam. The cracked eyebeam was unrelated to the detour installation. CCM worked around the clock to install a saddle to hold the cracked beam, with only a minor delay in reopening. But on Oct. 27, one of the repair beams cracked, dropping a 5,000-lb crossbeam and steel connectors onto the deck. During the ensuing six-day closure, North Highlands, Calif.-based MCM Construction Inc. repaired the work with enhancements.
Still, Caltrans declared it would close some lanes of the top deck each evening to inspect the repairs for vibration. Spokesman Bart Ney says all other eyebeams were inspected using ultrasonic testing and showed no cracking.
Richard Land, Caltrans chief engineer, says designing and fabricating a new eyebar could take up to four months. The bridge would have to be closed again during the repair and pre-stressing of the new beam. Ney adds that all possible design options will be considered.
Caltrans also has had to install additional safety measures in the temporary detour installed by CCM. More than 40 accidents have occurred since September, when the curving detour ramp was put in place, including the Nov. 9 death of a truck driver who drove off the ramp at 50 mph. Crews have installed reflective strips, flashing lights and warnings to reduce speed to 40 mph.
“The curve is safe for the range of speed posted,” Ney says. “We just need to get people’s attention.”