Re "Caltrans report did not address quakes" (Page A19, June 22): The Bay Bridge is surrounded with San Andreas, Hayward and Calaveras faults, able to generate huge earthquakes with accelerations several times the earth's gravity. Depending upon the bridge's properties such as its mass, damping, stiffness and foundation characteristics, these accelerations may be transformed into devastating forces turbulently swinging, twisting and shaking the bridge.
Surprisingly, Caltrans bridge engineer, Brian Maroney, made no calculations nor references to earthquakes in his 2011 report. Keith Devonport, a box girder consultant managing the project in China, was skeptical of the optimistic conclusion of this report.
For public safety, Caltrans' change orders allowing cracks to remain shall be made public, actual cracks be identified and examined periodically to see if these cracks grow and retrofit properly executed. Further, the bridge modeled with cracks - longitudinal and transverse - subjected to severe earthquake accelerations shall be carried out, confirming the structure is safe.
-- Vudinh Bon, Davis