New CA Bridge to Measure Seismic Activity
A replacement bridge being built south of Los Angeles is a first for those interested in monitoring seismic activity: Sensors were factored into the design of the span from day one, rather than being added later, which will allow for new data-monitoring opportunities.
The new 8,800-foot-long span over the Port of Long Beach, which will replace the Gerald Desmond Bridge, is being constructed with 75 seismic sensors. The bridge replacement is set to open next year.
Gerald Desmond Bridge Replacement
The original Gerald Desmond Bridge, a major access point to the Port, was opened in 1968, carrying I-70. The $1.29 billion replacement, a six-lane, cable-stayed design with 515-foot-tall towers, includes a 205-foot clearance for marine traffic, emergency lanes on the inner and outer shoulders and space for bicycles and pedestrians. To help maintain current traffic patterns, the new span is being constructed alongside the old.
According to ABC News, netting is placed underneath the old span to catch any concrete that breaks away. Duane L. Kenagy, the Port's interim deputy executive director, noted that the roadway is reaching the end of its usable lifespan, but it’s still safe for traffic until the replacement opens.
Main-span construction is well underway here at the Bridge Project. Who else is excited to see this angle once it’s complete? (PC: Instagram user 48thdistrictking) pic.twitter.com/x1vFTplysj— Gerald Desmond Bridge Replacement Project (@newgdbridge) September 6, 2018
The design-build project is funded in part by the U.S. Department of Transportation and the Los Angeles County Metropolitan Transportation Authority. Around 3,000 construction-related jobs were created thanks to the project. The old bridge is scheduled to be torn down.
Construction work is being spearheaded by the SFI JV, which is composed of California-based Shimmick Construction Inc., Spain-based FCC Construction and Italy-based Impregilo S.p.A. Arup served as the lead designer.
What makes the bridge the ideal candidate for using these sensors is its location—the span is just a few miles from two active faults, Newport-Inglewood and Palos Verdes. Data recorded by sensors built into the design will be sent via the state's Integrated Seismic Network to scientists working at state offices in Sacramento, and also sent to the University of California, Berkeley, as well as Pasadena's California Institute of Technology.
"New bridges don't come along very often, so it's exciting," said Dr. John Parrish, head of the California Geological Survey.
The agency’s Strong Motion Instrumentation Program will be among those monitoring the data, which will be added to the state’s collection of information regarding earthquakes.