The concrete support columns under Washington's I-5 and I-405 Bridges are hollow and filled with air. While construction is underway to replace some of these hollow columns that could collapse in the event of an earthquake, there are no current plans to prevent other hollow columns from collapsing on these two stretches.

Western Washington has more than 20 bridges like this with Washington State Department of Transportation officials knowing about the vulnerability for 15 years, and engineers knowing twice as long. The bridge builders of the 1960s discovered the weakness of these hollow columns but did not seem to care about earthquakes.

Today's engineers see the dangers associated with the bridge:

John Stanton, a University of Washington engineering professor, stood beneath Seattle’s Portage Bay bridge on SR 520, which is supported by hollow columns. He was in a grove of concrete columns in the Montlake neighborhood, with the humming highway roughly 50 feet overhead.

If an earthquake hit, he would "stop talking and run to get out from underneath the bridge very rapidly. This is not a good place to be in an earthquake," Stanton said.

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