MOUNT VERNON — Work is on track for the Interstate 5 bridge over the Skagit River to reopen in midmonth, the state Department of Transportation (WSDOT) said Monday.

The National Transportation Safety Board hasn’t finished its site investigation, but a contractor has started assembling a temporary span that can be rolled into position to replace the collapsed section, WSDOT spokesman Travis Phelps said.

A 160-foot section of the bridge crumbled May 23 when a truck carrying an oversize load hit a girder. The truck made it off the bridge, but two vehicles went into the water and three people were rescued.

Traffic is detoured through Mount Vernon and Burlington until a temporary bridge is in place.

WSDOT has installed traffic cameras near the detour points around the collapsed bridge. They make it possible to look at traffic online and plan accordingly.

Drivers have encountered the biggest delays heading northbound during peak commute times