Construction Starts on I-270 Bridge Over Mississippi River

Illinois, Missouri to Replace Chain of Rocks Bridge
Illinois bridge
Gov. J.B. Pritzker and other officials mark the beginning of construction to replace the Chain of Rocks Bridge. (Illinois Department of Transportation via Flickr)

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Illinois officials recently held a ceremony along Interstate 270 as construction started on a project with Missouri to replace the aging Chain of Rocks Bridge over the Mississippi River with twin bridges to help improve freight transportation.

Gov. J.B. Pritzker said, “This isn’t just an investment for the Metro East region — it’s an investment for our entire nation. This major freight corridor connects our ports and railways — essential to maintaining a steady supply chain for Illinoisans, Missourians and all Americans alike.”

Built in 1966, the existing Chain of Rocks Bridge over the river consists of two lanes going in each direction with narrow, one-foot shoulders that create safety issues when vehicles break down and for first responders. Illinois has determined the bridge must be demolished.

“As traffic counts have more than doubled since the construction of the current bridges, there is a critical need to replace the bridges and improve the overall safety for both passenger and commercial traffic,” said State Sen. Erica Harriss (R).

Renderings 1-27- bridge

Renderings of the new bridge on display at the ceremony. (Illinois Department of Transportation via Flickr)

The plan is to replace the bridge with one bridge on the same alignment as the existing one and another to be located south. Both new structures will have wider shoulders to allow for a later expansion of I-270 to three lanes in each direction. Completion is expected by Dec. 31, 2026.

Built in 1966, the current four-lane bridge supports the movement of 51,000 vehicles per day (of which 20% are trucks) on two lanes in each direction. This level of traffic today is significantly higher than a 1975 projection of 19,800 in average daily traffic crossing over the Chain of Rocks Bridge.

Partners in the joint $496.2 million project are both the Illinois and Missouri departments of transportation. In a $35.4 million companion project, MoDOT has designed a new diamond interchange for Riverview Drive at I-270 just west of the bridge that will be reconstructed to accommodate the IDOT Chain of Rocks bridge replacement.

I-270 construction

Camera view of the I-270 construction. (

The I-270 loop connects many regional warehouses and distribution parks, ports, airports and railyards on both Mississippi River shorelines.

“Nearly 70% of the region’s industrial tenants occupying large warehouse space in excess of 500,000 square feet are within 10 minutes of the interstate,” according to Illinois officials.

Lt. Gov. Juliana Stratton remarked, “The I-270 Chain of Rocks Bridge is transformative. We are witnessing how our investments in infrastructure are helping our communities provide commercial and transportation support while keeping us all connected,” said. “This bridge is a vital transportation asset between Metro East and greater St. Louis region.”

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