Photo by Tudor Van Hampton/ENR
Under Gannon's direction, Walsh crews preassembled the half-mile-long Milton-Madison Bridge truss and slid it into place.

A history buff who has enjoyed a 36-year career in construction, Charlie Gannon, a project manager for Walsh Construction, certainly appreciates the significance of having delivered the longest-ever bridge slide. Last April, his crews used strand jacks to pull a 2,428-ft-long, four-span truss 55 ft on refurbished piers, cutting downtime for motorists passing between the Ohio River towns of Milton, Ky., and Madison, Ind.


The Milton-Madison Bridge slide attracted ample attention, as onlookers from across the country came to watch the engineering spectacle. But building the temporary works to support the operation was the most challenging part of the job, Gannon admits.


"It was very complicated," he says. "To slide a bridge that size, you have to start with how well you build the supports you put underneath it. Most bridge slides are single spans, and they sit on basic temporary bents on either side. This was far from that."

To manipulate the 30-million-lb truss, Walsh built temporary towers made of 36-in.-dia pipe, with 1-in.-thick walls, driven 70 ft below the riverbed into bedrock and braced with barge-impact frames. The towers provided pick points for preassembled truss spans as well as launching girders for the slide.

At one time an avid skydiver, Gannon, 62, came with a lifetime of experience that prepared him for the high-pressure work. Colleagues call Gannon, who spent four years in the U.S. Army monitoring Russian communications in Czechoslovakia, an effective communicator and leader. He took a summer job in 1978 as a laborer and gradually worked his way up into project management. He suffered a horrifying accident one morning in 1996, when his hand got caught inside a drill rig, an experience that he says helped him to appreciate the importance of alertness on the jobsite.

"I've learned to live with it," Gannon says of the injury. "It ultimately made me a better project manager. When I stand up in front of people and want them to buy into safety, I can speak with authority."