Flaws in the design led to cracks during post-tensioning of the first four concrete pontoons built for the replacement of the world's longest floating bridge in Seattle, says the Washington State Dept. of Transportation. The fix could cost tens or even hundreds of millions of dollars and potentially delay the $4.13-billion project.

In detailing a report from a blue-ribbon review panel, state Transportation Secretary Paula Hammond maintained that the pontoons—designed to a 75-year life cycle—are structurally sound. But the report revealed that five cracks up to .03 in. wide on Pontoon W could leak and therefore require retrofits.