Bay Bridge

Memo 9-22-00

TO: (MTC) Bay Bridge Design Task Force
DATE: September 22, 2000
FR: Steve Heminger, MTC Deputy Executive Director
RE: Army Corps of Engineers report

As you may have seen in press reports, the Army Corps of Engineers released a report today answering the first of two questions it has been retained to review in an attempt to end the impasse over construction of the new east span of the San Francisco-Oakland Bay Bridge. The first question concerns whether Caltrans made the right decision in choosing to replace the east span with a new structure rather than retrofit the existing bridge. Key findings from the Corps report are as follows:

• Documents reviewed by the Corps did not demonstrate that any retrofit alternative met "lifeline" criteria which would ensure that the bridge could be used on an emergency basis immediately after an earthquake.
• Caltrans' lifecycle cost analysis suggests that the decision to select a replacement alternative may have been made even if the retrofit alternative construction costs were substantially less.
• Based on safety considerations, it is the Corps' conclusion that a replacement alternative is preferable to a retrofit alternative. "A replacement alternative is the path that most quickly resolves the exposure of the public to the seismic vulnerabilities of the existing structure."

Although the report does contain some criticism of Caltrans' retrofit design plans that were eventually abandoned in favor of replacing the east span in 1996, the Corps "does not disagree with the decision process" that led to the selection and ultimate abandonment of the retrofit design.

The second question to be answered by the Corps study is whether the replacement design recommended by your Engineering Design and Advisory Panel (EDAP) and approved by the Commission is seismically safe. The second report is due to be released on October 17, the 11th anniversary of the Loma Prieta earthquake.

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