Washington State Department of Transportation has committed to installing a temporary bridge by mid-June and a permanent span by mid-September.
In Missouri, two freight trains collided under a highway overpass on Saturday. The derailment caused the partial collapse of the overpass and a post-crash fire was also reported.
The two incidents follow a fire that caused a dramatic cascading collapse of a Texan railway bridge a few days before.
Asset management
28 May 13
Investigations under way into US bridge collapses
Investigators from the USA's National Transportation Safety Board have joined local officials in investigating a bridge collapse in Washington State and the partial collapse of an overpass in Missouri.
In Washington, a substantial portion of a bridge on the Interstate 5 collapsed into the Skagit River on Thursday evening. An oversized load struck the trusses that support the bridge.
