Missouri DOT New Mississippi crossing may be cable-stayed.

After two decades of planning and debating, the Missouri and Illinois transportation departments have agreed on a funding plan for a new $640-million Mississippi River bridge on Interstate 70 between St. Louis and Illinois suburbs. The goal is to relieve traffic on the interstate.

The Missouri Dept. of Transportation will pay $88 million and MoDOT will be responsible for any construction cost overruns on the bridge structure; Illinois will contribute $313 million. A revised environmental impact statement is awaiting federal approval, along with an expected $239 million in funding, says MoDOT project director Greg Horn. The revised EIS reduced the main span length from 2,000 ft to 1,500 ft as part of the process of cutting costs. Horn notes that in 2001 the bridge was estimated at about $2 billion.

The DOTs expect to hire a consultant in the next few months to begin final design of the structure. Since cable-stayed bridges are usually the most economical for that length range, Horn anticipates that will be the bridge type chosen. But the DOTs will be open to any other options the consultant comes up with, he adds.

The bridge itself will cost about $303 million. Related I-70 roadwork and an interchange with 1-55 and 1-64 on the Illinois side will account for about $264 million, and MoDOT will spend another $70 million on an interchange. The cost estimates are projected for 2010, when construction is expected to begin. Horn says the initial four-lane bridge will eventually be accompanied by a twin span—perhaps 20 or 30 years down the road.