The tractor-trailer is seen on videos passing on the left of the truck whose oversized load collided with the bridge trusses, causing a 160-foot span to crumble into the water.
Investigators want to get the driver's perspective on what occurred, said Washington State Patrol trooper Mark Francis. They also want to find out if the oversized load may have shifted after the collision and struck the tractor-trailer as it went by, he said.
"The driver may not even know if the oversized load struck him," Francis said.
Francis asked for the public's help in tracking down the driver and semi-truck via Twitter on Tuesday afternoon.
Investigators don't have much to go on. Francis said the trailer is white but had no description of the cab or a license plate.
The state patrol and National Transportation Safety Board are jointly investigating the May 23 incident.
State patrol investigators will interview the driver and provide the information to the federal authorities, Francis said.
Federal authorities have interviewed the driver for Mullen Trucking Co. of Alberta, Canada, whose load hit the bridge. They've also spoken with the people traveling in the two cars which plunged into the water after the span collapsed.
Anyone with information is asked to call Detective Sgt. Jerry Cooper at 360-805-1192.
Investigators were supposed to interview the pilot car driver on May 29, but that interview was postponed. It's unclear if that has occurred.
In another development Tuesday, the state Department of Transportation announced it will hold a community meeting in Burlington Thursday to discuss the short- and long-term fixes to the damaged bridge.
DOT engineers will present the plans for opening the temporary bridge this month and the proposed schedule for closing I-5 and detouring traffic in the fall when the permanent bridge section is ready for installation, according to a press release.
The meeting is scheduled from 7 to 8:30 p.m. at the Burlington City Council Chambers, 311 Cedar St., in Burlington.
Jerry Cornfield: 360-352-8623; email@example.com.
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