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The new Milton-Madison Bridge was scheduled to be moved into place yesterday. The slide of the structure, said to be the largest bridge slide of its type in North America, occurred after this week’s edition of The Trimble Banner went to press. However, updates, photos and a time-lapse video will be posted on our website at www.mytrimblenews.com when they become available.
The bridge, which spans nearly a half-mile and weighs some 30 million pounds, was to slide 55 feet laterally from its temporary piers and onto refurbished permanent piers.
In a briefing for the media Tuesday afternoon, representatives for the Kentucky Transportation Cabinet, Indiana Department of Transportation and Walsh Construction, contractor for the project, said the slide would begin shortly after daybreak Wednesday, at about 7 a.m. The officials said the procedure could take up to 16 hours before the bridge came to rest in its final location atop the refurbished piers that held the old Milton-Madison Bridge in place beginning in 1929.
The Coast Guard planned to close the river one-half mile upriver and one-half mile downriver from the bridge during the slide. The river taxi and ferry were also to cease during the operation.
“We’re making history in Indiana and Kentucky,” said Karl Browning, commissioner of the Indiana Department of Transportation. “Through hard work and creative engineering, we’ve been able to rebuild this bridge quickly and cost effectively.”
Pulling a half-mile structure weighing 30 million pounds a distance of 55 feet in a matter of hours is an engineering marvel, though simple in concept.
Walsh Project Manager Charley Gannon said seven workers would be on each of five piers during the slide operation. A total of 45 workers were to be involved with the slide plus the technicians from VSL, the subcontractor in charge of the slide for Walsh. The VSL techs will control the slide using the BRAVO system. The techs planned to boost the jack strength at the start of the slide to budge it loose, then go back to the original strength, Gannon said.
Gannon pointed out in Tuesday’s briefing that Walsh employees worked even in the rain during the days leading up to the slide as long as there was no lightening to complete preparations for the operation.
Polished steel sliding plates are secured on top of the refurbished piers. Steel cables and hydraulic jacks controlled by computers will be used to pull the bridge. A total of eight jacks are mounted on the piers. Industrial lubrication is put on the sliding plates to grease the skids. Then, through a series of grabs and pulls, the bridge is slid into place. Each grab and pull is expected to move the bridge 20–22 inches – up to 10 feet per hour.
Once the bridge is in its final position, additional work has to be completed before it can reopen, including inspections, welding and bolting it in place, reconnecting the driving surfaces, installing expansion joints, pouring concrete, configuring drainage and re-striping. But those efforts will be put on hold because at the end of the slide all workers will go for a good night’s sleep, Gannon said. Beginning today, the workers will work around the clock until the bridge opens.
“Everyone is a winner on this project,” said Mike Hancock, secretary of the Kentucky Transportation Cabinet. “We’re showing the rest of the country how two states, by strategically working together, can deal with aging infrastructure in creative ways that improve safety and better the quality of life for their citizens.”
All schedules are tentative because weather and other factors can alter the schedule. If all goes as planned, the bridge will reopen to traffic about a week after the slide.
The new steel truss bridge is 2,428 feet long and 40 feet wide with two 12-foot lanes and 8-foot shoulders – twice as wide as the old bridge. A 5-foot-wide cantilevered sidewalk will be added to the structure in the coming months after the slide.
EDITOR’S NOTE: Some information for this story was provided by Banner correspondent Cheryl Taylor.