A pilot driver escorting an oversize load that triggered the collapse of an I-5 bridge over the Skagit River told investigators that the clearance pole mounted on her car never hit the structure.
But in documents released by federal investigators Wednesday, one witness reported seeing the pole strike the Skagit River bridge several times, indicating there may not have been proper clearance for the oversize load.
The National Transportation Safety Board is investigating the May 23, 2013, bridge collapse and expects to release full findings this summer. On Wednesday, the independent agency made public more than 2,000 pages of documents, including interviews, cellphone logs, and incident reports.
A section of the span fell into the water after a truck carrying a tall load hit the bridge in Mount Vernon. Two other vehicles fell into the river, and three people were rescued with minor injuries.
William Scott, who was driving the truck with the tall load, told investigators that a freight truck “came up very fast on the left” and “squeezed me as we were coming to the bridge.” He told investigators that he moved his vehicle to the right — toward the side of the bridge that had less clearance.
As they approached the bridge, Scott said there was “a horrendous boom” and “it was violent in the cab.”
Scott told investigators that the pilot car driver was in the right lane when she entered the bridge. He says “the pole went through” and that she didn’t say anything about the pole hitting the bridge.
At the time of the bridge collapse, the vertical clearance was 18 feet above the center lanes but was tapered to 15 feet, 5 inches on the right side of the roadway. The lowest portion, measured over the shoulder of the roadway, was 14 feet, 8 inches, according to the NTSB.
Scott said he thought his load was 15 feet, 9 inches. The top of his load, a blue shed, collided with the far right side of the overhead truss structure.
The trusses have since been reconfigured by state transportation officials, giving 18 feet of clearance for all traffic lanes.
According to the NTSB, the driver of the pilot vehicle, Tammy Detray, said the clearance pole mounted on the front of her vehicle was set at 16 feet, 2 inches.
Detray’s interview with investigators was not recorded, at the request of her attorney. According to notes from the interview, Detray said the pole on her vehicle did not strike the bridge and that “a cloud of dust was the first indication she had that something was wrong.”
“She was watching the accident truck cross the bridge in her rear-view and side mirrors and saw dust and the bridge collapse,” the notes of the interview read.
She also told investigators she was using her cellphone on a hands-free device at the time of the accident and was talking to her husband about a route she would be taking the next day, according to a summary report.
Detray and Scott both said the pole didn’t strike the bridge, but the driver of a Ford Ranger, Dale Odgen, who was passing both vehicles, told investigators that as he was looking at the pilot car, he “saw the pole strike 4 or 5 of the bridge elements.”
“The Ford Ranger driver looked in his mirror and saw the load strike the bridge,” the report read. “He did not recall seeing a white commercial vehicle next to the accident vehicle and estimated the distance between the pilot car and the load at 100 to 150 yards.”
Scott cleared the bridge and stopped on the right shoulder, and did not realize that the bridge had collapsed until he was told by another driver who had also pulled over, according to the documents.
The 59-year-old bridge carries an average of 71,000 vehicles a day over the Skagit River on I-5. Workers installed an emergency span and then replaced it with a permanent span in September.