BRIDGES: Caltrans works to repair earthquake-damaged bridges

Aug. 24 shaker created minimal damage to 11 spans

Bridges News October 03, 2014
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Caltrans and its contractors have begun work on six emergency contracts to repair damage caused by an Aug. 24 earthquake in Napa and Solano counties totaling $5.3 million. Caltrans engineers and inspectors also continue to work with local agencies to assess and inspect damage affecting local bridges and structures.
 
Though no damage affecting public safety or the structural integrity of bridges resulted from the quake, the contracts, totaling $5.3 million, will result in final repairs to 11 state-owned bridges including fixing bridge seals, spalled concrete, damaged pavement, curb cracking and damaged bridge rails at locations on Highways 29, 37 and 121 in Napa and Solano counties. Work on an additional contract to repair pavement buckling on Highway 121 was completed within three days of the earthquake.
 
“One of Caltrans’ most critical tasks after an earthquake is to assess the impact on the state highway system’s bridges and roads,” said Caltrans Director Malcolm Dougherty. “In Napa, we were able to respond quickly thanks to seismic data which allowed us to prioritize our safety inspections of highways and bridges affected by the earthquake.”
 
Eight Caltrans building inspectors also were deployed to help the city of Vallejo, as only about 1,000 of 40,000 buildings in the city had been inspected for damage. Caltrans inspectors completed more thorough follow-up inspections of buildings that had been initially tagged for caution and canvassed areas for safety assessments where inspections still remained. The Caltrans teams also responded to calls from the public and fire and police departments to assess structural hazard concerns.
 
“In times of emergency, it’s all hands on deck to ensure the public’s safety, regardless of jurisdiction and responsibility,” continued Dougherty. “I’m proud of the Caltrans bridge and structural engineers and inspectors who were able to go out into the field to help Bay Area local governments and agencies assess the quake’s damage.”
 
Following the Napa earthquake, Caltrans used a rapid earthquake response tool called ShakeCast to identify which bridges may have experienced shaking. ShakeCast uses ground sensors to analyze earthquake shaking and provides data to the U.S. Geological Survey in the aftermath of a quake that immediately allows Caltrans to prioritize inspections of bridges and structures.
 
Within 48 hours of the earthquake, Caltrans inspected all seven Bay Area toll bridges and no damage was found on any of those structures. Caltrans bridge inspectors, working in four two-person teams, also inspected 29 state highway bridges in Napa, Solano and Contra Costa counties. Minor damage was found on eight bridges consisting mainly of spalled concrete, damaged joints and barrier rail and some pavement settlement of the bridge approaches. All bridges are fully open, structurally sound and safe for traffic and public use. For more detailed information on the damage to Caltrans bridges, a list is posted at http://www.dot.ca.gov/dist4/.
 
At the request of the city of Napa, Caltrans assisted with local inspections of three city-owned structures, one at Third Street and two on Soscal Avenue. Caltrans bridge inspectors also came to the aid of Napa County, inspecting 104 locally owned bridges for any earthquake-related damage. As a result of these inspections, nine of these bridges were found to have sustained damage. With the exception of the Garnett Creek Bridge north of Calistoga, which the county closed and will likely replace, damage to the bridges was minor and included concrete cracking and some settlement. Total cost for repairing the damage to the locally owned bridges is estimated around $2.7 million.
 

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