After seven years of construction at one of the nation’s busiest port complexes, California’s first vehicular cable-stayed bridge opened to traffic Oct. 5.
Construction of the new Gerald Desmond Bridge at the Port of Long Beach involved complex geologic challenges, delays and the use of mobile scaffolding systems (ENR 6/12/19). SFI, the design-build team of Shimmick Construction, Spain’s FCC Construction and Italy’s Webuild (formerly Salini Impregilo) built a 2,000-ft-long main span and 6,400 ft of approach spans with a 205-ft vertical clearance. But truckers carrying 15% of the nation’s inbound cargo across the span won’t be the only ones “seeing” it every day.
Next month, the California Geologic Survey will plant 74 accelerometers in, under and around the bridge, says Hamid Haddadi,the agency’s program manager for strong motion instrumentation. “It [will be] the first cable-stayed bridge we’ve instrumented,” he says.
According to Haddadi, 49 sensors will be installed in the towers, piles and caps. “We will have 13 sensors in the east approach. In addition, we are going to install 12 sensors … at different depths” to measure the response of the ground. The recorders will only retain the last 30 seconds at any time until the motions exceed threshold values, he adds. Then the real-time data will be available to some 15,000 registered users of the agency’s database.
Duane Kenagy, capital programs executive with the port, notes that the critical-lifeline bridge has 30-ft-long, 3-ft-dia shock absorbers and joints that can accommodate 6 ft of movement. “The bridge is designed to resist any anticipated earthquake we could foresee happening in Southern California,” he says.