Truck bed raised, slamming into QEW bridge

A woman has been seriously injured in a crash that began with the collision of a extended dump truck (similar the one inset )  slamming into the Lundy’s Lane overpass on the QEW near Welland. The box on the truck  was apparently raised  as the driver took his truck under the bridge. There’s no explanation as to why the bed was raised. A woman following behind the dump truck drove into the box.