Crews that built the now-closed Leo Frigo Memorial Bridge in Green Bay weren't able to rest its steel structure atop sturdy limestone bedrock, which some geologists and engineers say may have contributed to its sinking pavement.
Wisconsin highway officials discount that theory. They say steel corrosion at ground level is the likely culprit that forced the indefinite closure of the bridge, which carried about 40,000 cars daily over the Fox River.
The Green Bay Press Gazette reports Sunday that some experts say underground soil that was sturdy enough to support the bridge when it opened three decades ago might have deteriorated in subsequent years. Bill Kallman, a Michigan engineering consultant who has worked on bridges in New York, says he thinks that's a more plausible explanation than corrosion.