Work on a new Mississippi River Bridge will significantly impact traffic in the downtown St. Louis area in early October, transportation authorities announced. Various closures are scheduled for bridge demolition and construction work.

On October 3, the Missouri Department of Transportation will close Interstate 70 express lanes at 9 a.m. The lanes will remain closed until mid-December. This closure is a part of constructing new ramps between I-70 and the new bridge.

October 7, MoDOT will reopen the Cass Avenue Bridge over I-70. It was closed in 2007 because of safety concerns and was demolished in February 2010.

Work started on a new Cass Street Bridge earlier this year, and it will reopen after a 10 a.m. ribbon cutting ceremony. Regular traffic will be able to use the new bridge to cross over I-70 later that afternoon.

On October 7-10, MoDOT will close the Howard and 9th Street bridge over I-70 to remove it. The department will need to close I-70 between 10th Street and the Poplar Street Bridge during the demolition. The interstate will close at 8 p.m. October 7 and reopen at 5 a.m. October 10.

The ramps from the Poplar Street Bridge to both I-70 and Memorial Drive will be closed while the interstate is closed. If possible, drivers should use I-64 and I-170 to detour around the closure. There will be a detour for local traffic that involves several miles of city roadway and about a dozen city traffic signals.

Finally, crews will permanently close the 10th Street ramp from eastbound I-70 (exit 249A) at 9 a.m. on October 10. Closing this ramp lets crews start constructing new ramps between I-70 and the new Mississippi River Bridge. Drivers who normally use the 10th Street ramp cam use the next exit, Broadway, to access that area.

The new bridge, along with I-70 relocations in Missouri and Illinois, is estimated to cost $667 million and is to be finished in 2015. It will be 2,803 feet long and feature two A-shaped stay-cable supports rising 435 feet above the roadway. More details: