BRIDGE CONSTRUCTION: New Bay Bridge opening will be delayed

Oversight committee’s final report confirms bolts failed because of hydrogen embrittlement

Bridge Construction News Caltrans July 10, 2013
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The previously scheduled Labor Day opening of the new East Span of the San Francisco-Oakland Bay Bridge has been postponed, the Toll Bridge Program Oversight Committee (TBPOC) announced yesterday. TBPOC also released its investigative report into the 32 bolts that broke on the Bay Bridge in March and its review of other bolts on the bridge.

 

The investigative report stated in part: “The A354 grade BD anchor rods installed on the lower housing of shear keys S1 and S2 failed due to hydrogen embrittlement. The three conditions of susceptible material, high tensile strength and the presence of hydrogen all were present, leading to crack extension and brittle fracture. The actions taken and decisions made on the design and specifications, fabrication, and construction activities are all contributing factors to the rod failures.” The report is available at http://www.mtc.ca.gov/projects/bay_bridge/A354_report.pdf.

 

The contractor now forecasts that the steel saddle retrofit of the failed bolts on the east pier will be completed by Dec. 10, 2013. TBPOC will select a bridge opening date based upon actual completion of the east pier retrofit work, weather windows, traffic impacts and other information as it becomes available. The bridge opening may or may not coincide with a Monday holiday weekend and may involve shorter advance notice to the public than prior closures.

 

A four-day full closure of the existing bridge is necessary to complete construction work at the Oakland touchdown and Yerba Buena Island tunnel in order to transition traffic from the old span to the new one.

 

The TBPOC also released its final investigative report, which lays out at length the chronology of events and assigns proper responsibility as warranted. The findings, and all other information contained in the report can be found at websites for the Bay Bridge, Caltrans and the Metropolitan Transportation Commission. In addition to the report, thousands of additional pages of documentation and records have also been posted on those websites.

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