(KUOW, Seattle) Federal investigators have some ideas about what led to last month’s I-5 bridge collapse over the Skagit River.
The preliminary report, released Tuesday, says the driver of the truck that struck the bridge before it fell had moved over closer to the edge of the bridge because of a passing truck.
The bridge collapsed on May 23 after a truck carrying an oversized load hit supports along the top.
According to the National Transportation Safety Board, the truck driver told investigators that he felt “crowded” by another semitruck that was trying to pass him on the left, so he moved to the right.
That confirms eyewitness accounts. One of them was from Dan Sligh. The night of the crash, he told KING 5 News that the second semi almost penned in the oversized truck.
“At that point the wide load caught the right side of the bridge," he said. "There was a loud boom. A big puff of dust appeared.”
Shortly after the puff of dust, the bridge span fell into the Skagit River.
The right lane had less clearance than the left lane, and the NTSB has previously said the oversized load could probably have crossed the bridge safely if it had been in the left lane. But the agency is still working to verify that.
The new information raises questions about bridge safety and truck regulations. For example, if a pilot car had been trailing the wide load, it could have prevented the second semi from passing. But that wasn’t required under current regulations.
Jim Wright, Washington State Department of Transportation’s program manager for oversized loads, said pilot cars that follow oversized loads have an important role. “They tell the operator of the transport vehicle, traffic that’s approaching from the rear, and if need be they can close off a lane so that transport vehicle can move over into that lane,” he said.
Under current rules, the load that hit the bridge was too small to require a rear pilot vehicle.
The NTSB continues to investigate. A WSDOT spokesman said the agency had no comment until the federal investigation is complete.
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