MAINTENANCE ON BRIDGE RESUMES NEXT WEEK

More maintenance work is planned on the Mississippi River Bridge beginning next week while construction of the new Bill Emerson Memorial Bridge, delayed by high water in the spring, now is being slowed by low water.

Bridge traffic on the Illinois side of the river will be reduced to one lane beginning Tuesday as crews from the Missouri Department of Transportation begin work on the driving surface of the bridge and on a sway bar underneath the bridge. The one-lane traffic will be in effect from 7:30 a.m. until 4 p.m.

The work is scheduled to continue Monday through Friday for about three weeks and is expected to cause delays of 15 minutes.

Meanwhile, work on the Bill Emerson Memorial Bridge has been delayed about three weeks by the need to remove sand inside the coffer dam that has been built in the middle of the river.

The dam was built so that a jet grouting process could be used to repair the river bedrock where seams of mud have been found. But Scott Meyer, district engineer for MoDOT, says the low level of the river is making it necessary to remove sand to maintain the equilibrium of forces pushing against the metal dam from both the inside and outside.

He said the dam is designed to withstand a certain amount of differential in forces but engineers want to remove the sand as a precaution against what could happen. Conversely, the low water has helped speed work on the bridge on the Illinois side.

The maintenance on the Mississippi River Bridge is work that originally was going to be awarded to a contractor last summer and would have required closing the bridge at night. But MoDOT twice took bids on the project and both times the bids were considered too high once by 40 percent and the second time by 25 percent. The state does not want to over-invest in a bridge that is going to be replaced in a few years, Meyer said, so MoDOT is doing the work itself on a smaller scale."If we didn't have a replacement bridge we would be looking a a major rehabilitation," he said. "... We could add life by doing that but it still would not be any wider and we still would have limitations for load."The speed limit on the aging bridge has been reduced to 25 mph both to promote safety because the bridge is so narrow and to protect its ability to handle loads. Meyer said steel plates will be put down on the road surface in places where asphalt has fallen through the grid. He emphasized that the grid itself can support the traffic going over the bridge. The plates are being added to provide a smoother ride.

Meyer said so much of the work is being done on the Illinois side of the bridge because there are many more joints on the approach span. Sway bars counteract the effects of lateral forces on the bridge, such as wind, and help the bridge work as a unit rather than as separate parts, especially during construction. Meyer said they are not critical to the bridge's function.

The MoDOT work crews from Jefferson City will be helped by workers employed by the district office.

The state agency asks that motorists use alternate routes, if possible, during the lane closure.

More closures are expected in coming months as the maintenance work is done on a more piecemeal basis than the original plan would have allowed by closing the bridge at night."We can't have the amount of production that would be necessary to get it done in a short amount of time," Meyer said.