Bay Bridge Quake Retrofit Awes Engineers

Rochester, Minn. — Hassan Astaneh's analysis of the 35W bridge collapse concludes that MnDOT, the construction company PCI and URS Corporation, the consulting firm that evaluated the bridge, could have prevented the collapse.

Astaneh is a professor in University of California Berkeley's Civil and Environmental Engineering Department whose work includes studies on the collapse of the World Trade Center for the National Science Foundation. He's been hired as a consultant by one of the lawyers representing some of the victims of the bridge collapse. His paper on the 35W bridge disaster is the keynote address at International Conference on Steel Bridges. Astaneh provided MPR News with an advance copy.

Bridges are designed to bear one and a half to two times their intended weight, Astaneh says. That margin is a safety net that accounts for design errors.

MnDOT had already eaten into the bridge's safety net when it added two inches of concrete to the deck in 1998, Astaneh claims. The 35W bridge deck was nine inches thick. Normally a bridge's deck is six to seven inches thick, Astaneh says.