Construction Begins on New Chain of Rocks Bridge Over Mississippi River

Construction has begun on a new bridge for Interstate 70 over the Mississippi River, connecting Missouri and Illinois. The new bridge, known as the Chain of Rocks Bridge, will be constructed parallel to the existing bridge that was opened in 1966 and will eventually replace it. The project is being carried out by Walsh Construction, who has been preparing for the construction of the new bridge’s substructure, as per the Illinois Department of Transportation.

In addition to the new bridge, the project includes the construction of a new diverging diamond interchange at the I-270 Riverview Drive intersection in St. Louis. The ramp of the interchange has already been closed for work and will remain so until July 2024, according to the Missouri Department of Transportation. The project is a collaboration between IDOT and MoDOT.

Initially, the new Chain of Rocks Bridge will open with four lanes, but it will eventually have six lanes after the east and west sections of I-270 are widened to six lanes. Similarly, the Riverview Drive interchange will also be widened to six lanes but will initially be striped for four until the other sections are widened, as per MoDOT. The construction is expected to be completed by the end of 2026 at a cost of around $500 million.

The current Chain of Rocks Bridge consists of twin bridges with 43 spans and is 5,400-foot-long. It handles approximately 51,000 vehicles daily, with around 17% of them being trucks, according to IDOT. The existing bridge is reaching the end of its design life and has undergone various repairs, including structural steel and substructure repairs, as per the agency. Once the new Chain of Rocks Bridge is completed and opens, the old bridge will be demolished, and the next span will be built in its place.