Newspaper article St Louis Post-Dispatch (MO)

Widening of Poplar Street Bridge Involves Novel Approach

Newspaper article St Louis Post-Dispatch (MO)

Widening of Poplar Street Bridge Involves Novel Approach

Article excerpt

ST. LOUIS - Widening the Poplar Street Bridge - a notorious commuter choke point - could soon involve picking up and sliding the eastbound lanes 9 feet to the south, then adding a new lane down the middle of the span.

Transportation planners last month endorsed the $21 million project as part of a compromise to replace an interchange that ties together the Poplar Street Bridge with Interstates 44, 55 and 64 on the Missouri side of the Mississippi River. The combination of bridge and highway fixes will help ease bottlenecks on the bridge - but more importantly, the proposed fifth eastbound lane helped break political gridlock between Missouri and Illinois leaders, who fought for months over the removal of a key ramp.

Lifting, splitting and widening a bridge over the Mississippi River may sound drastic, but the engineering is relatively simple and quick, said Cory Imhoff of HDR Engineering Inc., who developed the idea.

"It is not really that complicated," he said.

It is, however, fairly new to Missouri. The Missouri Department of Transportation used a similar technique in May 2011 to replace the westbound Interstate 44 lanes over the Gasconade River. The method involves adding reinforced concrete to extend the existing piers rather than sinking new piers to support a new section of road.

By using the construction technique, I-44 traffic was choked down to one lane for only 20 days instead of 60, officials said.

There, MoDOT's contractor built a 670-foot bridge deck and underlying girders next to the existing bridge. Using hydraulic jacks, crews slid the new 2,000-pound superstructure into place. Traditional construction methods would have closed westbound lanes for two months, MoDOT officials said.

Imhoff said the Gasconade River project and the proposed lane addition to the Poplar Street Bridge follows tenets of "accelerated bridge construction." The approach stresses short closures and stepped up construction timetables. And in this case, lower cost.

Similar bridge-building techniques have been used in other parts of the country.

The idea to add eastbound lanes to the Poplar Street Bridge surfaced after the East-West Gateway Council of Governments hired HDR this year.

The engineering firm was tasked with looking at a Missouri plan to remove the ramp linking Interstate 70 and downtown St. Louis to the Poplar Street Bridge.

The Missouri plan proved unpopular with Metro East leaders who feared it would remove a vital link to Southern Illinois.

The HDR review supported MoDOT's original plan to remove the I- 70 ramp as part of the $54. …

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