First of several steps in innovative replacement of US 421 bridge
LOUISVILLE, Ky. (July 5, 2012) — The “big lift” operation for the Milton-Madison Bridge Project has been completed, successfully placing the first span of the new bridge onto temporary piers. The lift is the first of several steps in the innovative replacement of the US 421 bridge, which connects Milton, Ky., and Madison, Ind.
One of the more intricate parts of the lift, which concluded today, involved the crucial placement of two “sliding girders.” The 125-ton beams were positioned under the truss, supported by the temporary pier and specially designed concrete pedestals on the existing piers. The sliding girder beams will be used next year when the new 2,400-foot bridge “slides” from the temporary piers to the permanent piers, which are being rehabilitated and strengthened. The project’s second and final span lift is scheduled for later this summer.
Moving at a rate of about 12 feet per hour, last week’s span lift took a total of seven hours to complete. The massive 600-foot segment was hoisted into place using special hydraulic “strand jacks” and bundled strands of steel cable. The span, roughly the size of two football fields, weighs 1,776 tons, or three and a half million pounds. The existing bridge remained open throughout the span lift operation.
“Because of the massive size and weight of bridge spans, lifts like this are pretty rare,” said Jason Bunselmeier, construction area engineer for the Indiana Department of Transportation (INDOT) Seymour District. “Contractor Walsh Construction and consultant VSL International did a masterful job pulling it off.”
A joint effort by INDOT and the Kentucky Transportation Cabinet, the $103 million replacement of the narrow and deteriorating 1929 bridge began in early 2011 and is scheduled to be complete in 2013. Because the existing piers are being reused, the new wider bridge will lie within the footprint of the existing bridge.
Named one of the Top 10 bridge projects in the country by Roads & Bridges Magazine, the Milton-Madison Bridge Project has been the recipient of several state and national engineering awards for innovation. For more information, visit www.MiltonMadisonBridge.com.
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