By Mary Lamie, Contributing Author
Construction on the new Interstate-270 Chain of Rocks Bridge over the Mississippi River marks another significant milestone for infrastructure investment in the St. Louis area. It also is a testament to the strength of the continued collaboration that is helping to add capacity and redundancy to the region’s freight network.
Over a three-year period during the project planning phase, more than $600 million in funding was secured by both the Missouri Department of Transportation (MoDOT) and the Illinois Department of Transportation (IDOT) for the bridge replacement, as well as improvements to adjacent sections of I-270.
The project is part of a regional plan to improve a 30-mile section of I-270 from James S. McDonnell Boulevard in Missouri to Illinois Route 157 in Illinois. Fast forward to today, over $1 billion in funding has been secured for this corridor for construction, as well as partial design of new interchanges, additional lanes, and other interchange improvements.
Recognizing the importance of this Mississippi River bridge crossing to the movement of freight through the region, the St. Louis Regional Freightway has counted its replacement among its highest priority infrastructure projects for the past several years. It also helped to garner support for this project from the East-West Gateway Council of Governments’ Board of Directors.
These efforts included collaboration with freight industry leaders, IDOT, and MoDOT. They supported the project based on connectivity to other modes of transportation, such as rail, river, and air and providing global access to shippers and carriers throughout the world.
Maintenance costs continue to rise due to the bridge’s age, which was built in 1966, and to increased traffic volumes and safety issues associated with narrow shoulders.
Traffic has soared from an estimated 19,800 vehicles per day in 1975 to approximately 50,000 vehicles per day currently, with nearly 20% of those vehicles now being trucks. At four lanes wide, the current bridge creates a severe freight bottleneck and is not equipped to handle the large freight flow increases forecasted for the region.
This joint project will deliver a new bridge providing two lanes in each direction, expandable to three, and a 10-foot shoulder from Riverview Drive in Missouri to the Chain of Rocks Canal on the Illinois side.
Construction includes new twin bridges, with the northern structure on the same alignment as the existing I-270 Chain of Rocks Bridge, and the southern structure adjacent to the northern structure. The new bridges’ inside and outside shoulders will be wide enough to accommodate a stalled vehicle or emergency responders handling an accident.
This a dramatic improvement compared to the one-foot shoulders that exist today.
This collaborative, future-focused approach will ensure the project serves this region for decades to come. It also helped to draw the unanimous support of the Freightway’s Freight Development Committee for inclusion of the I-270 Chain of Rocks Bridge project on the Priority Projects’ list.
That helped raise awareness about the need to replace the structure and demonstrated that all constituents see the benefits of this project to the entire freight network, making it a stronger candidate for funding.
With inflation impacting construction costs, the new bridge alone now has an estimated cost of $496 million. That makes securing funding for this local project one of our region’s greatest examples of successful regionalism and unified support for infrastructure investment. We salute IDOT and MoDOT for their historic partnership and look forward to gathering as a region to celebrate the opening of the new I-270 Chain of Rocks Bridge in late 2026. R&B
Mary Lamie is Executive Vice President of Multimodal Enterprises for Bi-State Development and head of the St. Louis Regional Freightway.
