Constructed in the 1890s, Merchant’s Bridge spans the Mississippi River and now is 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) is replacing the main span and east approach of this historic structure. The new structure will replace the existing three with truss main spans up to 520 feet in length. The east approach includes six-deck plate girder spans constructed in 2006 and 31 multi-beam spans. A study identified the river span configuration that provided the most cost-effective, constructible solution, and satisfied all permitting requirements. Also included in the east approach design is a unique cellular concrete retained fill replacement of the existing 1890’s spans. The bridge type study results determined that the best option was to replace the existing three truss spans, strengthen the river piers, modify the deck plate girder spans, and encase the east approach spans. The existing main span through trusses will be replaced with ballast deck truss spans. The stone masonry river piers will be encased in concrete to resist Level 3 seismic and AASHTO vessel collisions. Deck plate girder spans will be widened from 12-foot to 15-foot and ballast deck will be added. There are six railroad stakeholders including CSX, BNSF, UPRR, Norfolk Southern, Canadian National, and Amtrak, who are all major stock holders of TRRA as well. This presentation includes aspects of a mega-transportation project in the St. Louis metro, asset management, historical preservation, and bridge inspection methods.