Merchants Bridge Main Span Trusses & East Approach Construction

Merchants Bridge is one of two rail bridges that carry five Class I railroads and Amtrak across the Mississippi River in the St. Louis area. This replacement project doubles its freight traffic capacity, an effort that officials have called their top infrastructure project in the Missouri-Illinois bistate area in the past seven years. Based on our experience with long-span and complex bridges, CMT was contracted to perform construction quality assurance inspections on the truss spans and to assist with the response to design RFIs and submittals. 

This 2742’ long bridge project included replacing 1551’ of main span truss and reconstructing 1191’ of approach spans. Merchants Bridge spans the Mississippi River and has been identified as the top priority freight improvement project in the St Louis region. The bridge’s current capacity limits the existing double-track bridge to allowing only one train to pass at a time causing significant delays in freight movement. Terminal Railroad Association of St. Louis (TRRA) decided in 2015 to replace the main river spans and reconstruct the east approach spans. The existing bridge was built in 1894 and consists of the three 517’ through truss spans, 447’ of deck plate girders, and 744’ of girder spans. 

The new structure is three through truss main spans up to 520 feet in length. The east approach includes six deck plate girder spans to be modified for ballasted deck and 31 multi-beam spans to be encased in cellular concrete behind MSE walls.