From Bill's link:

"State officials approved the trucking company to carry a load as high as 15 feet, 9 inches, according to the permit released by the state. However, the southbound vertical clearance on the Skagit River bridge is as little as 14 feet, 9 inches, state records show. The bridge's curved overhead girders are higher in the center of the bridge but sweep lower toward a driver's right side."

And further:

"The bridge that collapsed was inspected twice last year and repairs were made, Peterson said. It was not classified as structurally deficient, but a Federal Highway Administration database lists it as "functionally obsolete"—a category meaning that the design is outdated, such as having narrow shoulders and low clearance underneath."

As I said.

Don Firth