The truck driver whose load made contact with the Interstate 5 bridge in Washington that was said to cause the bridge’s collapse said he “felt crowded” by a tractor-trailer passing him on his left and moved to the right, where he made contact with a portion of the bridge reportedly a foot shorter than his load, according to a recently released report from the National Transportation Safety Board.
The May 23 incident occurred on an I-5 bridge spanning the Skagit River near Mount Vernon, Wash., and the bridge collapsed into the river. No one was hurt or injured, though two passenger vehicles fell into the river.
According to NTSB’s report, the top of the oversized load that struck the bridge collided with an overhead portal and some sway braces on the far right side of the bridge’s truss structure. “The impacts caused significant damage to load-bearing members of the bridge’s superstructure,” according to the report, “resulting in the failure and subsequent collapse of the northernmost bridge span.”
In post-collision accounts of the accident, the driver said he thought his load was 15 feet, 9 inches tall. The pilot vehicle that was leading the truck said his clearance pole was 16 feet, 2 inches high and reportedly cleared the bridge. The lowest portions of the bridge, however, were 14 feet, 8 inches, the report says.
The bridge was built in 1955 and some of its over-water trusses were “considered to be fracture critical,” says the report.
The truck that hit the bridge was a 2010 Kenworth towing a 1997 Aspen flatbed with a casing shed. It was following a pilot vehicle heading southbound on I-5.