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If the number of daily commuters were a barometer of its popularity, the Blanchette Memorial Bridge might be considered somewhat of a celebrity.

But unlike Hollywood celebrities who need 30 days at a rehabilitation facility to remake themselves for the public, this St. Charles icon needs more than a face lift. And it will take up to two years to finish the job.

The Missouri Highways and Transportation Commission on Wednesday awarded a $62.7 million contract to Chicago-based Walsh Construction Co. for repair and replacement work on Blanchette's westbound span, which opened in 1958 and is the oldest of the bridge's twin spans.

The Missouri Department of Transportation expects to have the contractor's construction schedule in January, said MoDOT spokeswoman Linda Wilson. The contractor will have a 12-month window to detour all Interstate 70 traffic to the eastbound span and cannot impact traffic on either bridge after Dec. 31, 2013. The dates of the closure won't be available for several months. The entire project must be finished by April 2014.

About 160,000 vehicles per day cross the Missouri River on the Blanchette Bridge.

Wilson said she's already heard from concerned commuters who think the westbound span will be closed by Jan. 1.

"That's not happening," she said. "I expect it to be sometime later in 2012 because they have so much steel and supplies to order."

Unlike MoDOT's plan to spend $125 million to replace the old westbound span of the Daniel Boone Bridge on Highway 40, the westbound span of Blanchette will not be entirely replaced. The Blanchette work includes replacing the truss sections, replacing the driving surface of the five-lane bridge, and repairing or replacing many other major elements, including the superstructure.

To help the flow of traffic while Blanchette gets its overhaul, MoDOT is adding an extra lane in each direction on the Discovery Bridge, which takes Highway 370 across the river on the north end of St. Charles, and is reconfiguring the intersection of Muegge Road and Old Highway 94 to add a second lane to the on-ramp at the Veterans Memorial Bridge, which takes Highway 364 (Page Avenue extension) across the river on the south side of St. Charles.

Wilson said work at the Muegge/94 intersection is almost finished, and the extra lane to the on-ramp of the Veterans Memorial Bridge will be permanent.

The restriping of the Discovery Bridge has started and the extra lanes will take away the two spans' shoulders during the lane closure segment of the Blanchette construction. Once the Blanchette lanes re-open, the extra lanes on Discovery would be reverted back to the bridge's shoulders.

"The biggest challenge is getting the coordination of the alternate routes together, making sure that everything can happen," Tom Evers, Blanchette Bridge project manager for MoDOT, said earlier this year. "A 12-month closure is great to get the work done, but to get the traffic moving through the region will take quite an effort."

MoDOT also is in the process of restriping westbound I-70 at I-270 to add a second lane to the I-270 on-ramp. That change will be permanent. Wilson said that project is intended to make it easier for commuters traveling west on I-70 to access I-270, which will lead them to the Veterans Memorial Bridge and away from Blanchette.

"We'd like to encourage people to make that an option," Wilson said.

There are four ramps at I-70 and South Fifth Street in St. Charles. The South Fifth Street exit is the first for drivers traveling over the westbound span of Blanchette. The entrance ramp from Fifth to eastbound I-70 is the only ramp at the interchange that will be closed during the construction. Wilson said that ramp must be closed for driver safety.

"When you get on that ramp you're basically on the bridge; it's super tight there," Wilson said. "If we left that ramp open, we'd have to put a stop sign there and that's not safe."

Wilson said MoDOT expects 33 percent of motorists who use Blanchette will need to find an alternate route when construction begins. Highway 370 carries an average of 67,000 vehicles per day across the river. MoDOT expects that number to increase by 15 percent. Highway 364 averages 60,000 vehicles per day across the river; MoDOT expects that to increase by 20 percent.