ST. LOUIS, Mo. - On Saturday, March 31, construction crews will carry out the relatively unusual maneuver of picking up and moving the four eastbound lanes on the Poplar Street Bridge 9 feet to the south.
That will allow space to build a new fifth eastbound lane between now and December, when the bridge project is expected to be completed. The westbound lane total will remain at four. Missouri and Illinois are adding a fifth eastbound lane to the bridge and making other updates. The $54 million project aims to ease traffic congestion.
The slide and new eastbound lane are just part of a $54 million overhaul aimed at reducing traffic congestion, improving safety and extending the life of the Mississippi River bridge, which opened in 1967, another 25 to 30 years.
The Missouri Department of Transportation, which is in charge of the project, says the shift of the 2,165-foot-long section of roadway will be the second longest bridge slide in U.S. history.
Michelle Forneris, MoDOT's area engineer for St. Louis, adds that this one is unique because other slide projects typically involve construction of all-new bridges on temporary piers, then moving them to older permanent piers.
That includes the record-holder for length, a 2,427-foot replacement bridge built in 2014 across the Ohio River between Milton, Kentucky, and Madison, Indiana.
MoDOT officials say the method was chosen here partly because it's less expensive than adding a new eastbound lane on the right. They also say it will make the bridge, which now is two separate spans separated by a narrow gap, stronger by tying them together.
In preparation for the slide (and construction of the new lane during the coming months), the spaces between the columns supporting the bridge have been partly filled in by extending the reinforced concrete, creating wall-like piers.
Forneris said 26 hydraulic jacks on the piers will raise the 20.4-million-pound stretch of roadway about an inch; the moving process involves special pads and a slide track.
The shift will take as long as 12 hours