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THE DAY WE'VE BEEN WAITING FOR
MOVE THAT BRIDGE
, Courier Staff Writer
Wednesday, April 09, 2014 11:00 AM
READY TO SLIDE: Charlie Gannon, project manager for Walsh Construction, answers questions about the Madison-Milton Bridge slide during a press briefing Tuesday. The bridge slide was scheduled to begin this morning. (Staff photo by Ken Ritchiefirstname.lastname@example.org)
HOW IT WORKS: Pier 4 has guide rails along each side of its slide plate as a steering mechanism for the procedure. All of the jacks are outfitted with a laser monitoring system, which is hard-wired so that the jacks on each pier can communicate with each other, ensuring that all parts of the bridge are moving at the same speed. As the cables are pulled through the jacks they move out over the curved rail at the end of the piers. (Courier file photo by Ken Ritchieemail@example.com)
Officials outlined plans Tuesday for the Madison-Milton Bridge slide, which was scheduled to begin just after sunrise this morning.
The slide - the longest bridge slide in North America - is expected to move the 2,428-foot steel truss bridge onto its refurbished piers 55 feet to the east of the temporary piers.
Eight jacks will pull the superstructure over polished steel plates to the bridge's permanent home atop the piers that once held the 1929 Madison-Milton Bridge.
The bridge slide is expected to take anywhere from four to 16 hours.
Walsh Construction project manager Charlie Gannon said the nearly 30-million-pound bridge superstructure will be moved through a six-step process.
After daybreak, crews were expected to begin the slide by completing a "breakout" of the bridge by moving the superstructure three inches. This will allow crews to see that the structure is free and ready to slide.
Crews will move the bridge 25 feet through a series of grabs and pulls during the second step.
Strands of cable threaded through each jack will move the bridge by grabbing the cable and pulling before securing the cable strand, then repeating the method. Each grab-and-pull sequence will move the bridge about 20 to 22 inches each time.
After the second step, crews will take a break in the slide process to check equipment.
The third step will move the bridge another 25 feet before crews add necessary welds to connecter plates.
The fourth step will take the bridge another five feet and the fifth step will move the bridge another foot. The superstructure will be within a half-inch of its final position on the permanent piers by the end of the fifth step.
The sixth step will move the bridge a final half-inch to the bridge's permanent location.
Nearly 45 workers and technicians will work to complete the bridge slide by using the BRAVO jacking system, which was used to lift each section of the bridge structure to its location on the temporary piers.
The computerized BRAVO system uses lasers that can be calibrated to within 3 millimeters on each jack to monitor the slide, Gannon said. The lasers help to signal crews to shut off the jacks once each maximum distance is reached.
Gannon said all workers would be allowed to go home after the slide to rest before resuming 24-hour-a-day schedules to reopen the bridge about a week after the slide.
Crews will need to complete some concrete work, guardrail installation, roadway striping and installation of expansion joints before traffic will be allowed to travel on the bridge.
Kentucky Transportation Cabinet spokeswoman Andrea Clifford said the U.S. Coast Guard will shut down the Ohio River about a half-mile away from the construction zone in both directions during the slide.
No other river traffic will be allowed in the zone during the bridge slide, she said, and no passenger ferry service is expected to be available during the slide.
BRIDGE SLIDE ON HOLD
PHOTOS: MOVE THAT BRIDGE
Why can't the bridge be opened to pedestrian traffic as soon as the slide is complete. Numerous people would rather walk across for the next week than drive the three hour round trip
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4/9/2014 11:46:00 AM
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