It’s a race against time to get the $6-billion San Francisco-Oakland Bay Bridge built before the next Big One. From spiral reinforcement column cages to steel hinges, the bridge showcases the latest seismic-resistance techniques.
The 1989 Loma Prieta earthquake heavily damaged the eastern span of the old Bay bridge, a double-deck truss. A portion of the upper deck collapsed, killing one person and closing the bridge for a month (ENR 10/18/90 p. 36). Under performance-based criteria, a “lifeline” bridge is to be serviceable after a major quake.