 As one of the most traveled stretches in Kentucky, Clay's Ferry Bridge in Fayette-Madison County had a problem. To perform annual inspections of spans underneath the bridge as mandated by the federal government through Title 23, inspectors needed to navigate sharp angles and walk on precarious, narrow lengths of bar grating. At 200 feet above the Kentucky River, these rickety walkways created a potentially dangerous situation-not to mention an uneasy experience for inspection workers. A safer, more efficient method was needed to allow workers adequate access to the bridge's underside. The solution: Heavy Duty GRIP STRUT® U-Shape Walkways from Cooper B-Line - GS Metals CORP..
The Bridge Expansion
Along Interstate 75, there is an incredible amount of traffic. In an effort to accommodate the increasing numbers of vehicles and meet Federal Highway Administration recommendations, Kentucky Department of Transportation (KDOT) officials have undertaken massive expansion projects to expand the four-lane highway to six. The stretch over the Kentucky river near Lexington, known as the Clay's Ferry Bridge, began renovation in October 1993.
"We started this project at a policy level," said Al Frank, KDOT bridge engineer. "We decided to replace the existing catwalk system as we built the bridge. This was a perfect opportunity to upgrade."
The actual structural rehabilitation and expansion of the bridge was done in three phases to minimize traveling inconveniences and congestion. During each phase, entire sections of the 30-foot-wide bridge were demolished and rebuilt, while one traffic lane was kept open. Construction crews actually erected six sections of bridge, three on each side, by the time the last construction phase was completed in mid-1996.
The existing walkway system before demolition of the bridge consisted of thin bar grating at steep angles, with several supports underneath. Galvanized steel cables were strung across the interior cords to act as railings. According to Frank, the KDOT originally envisioned setting up a new main walkway consisting of a bar joist with grating attached to it, bolted to steel girders on the bridge's underside. This idea was later dismissed in favor of a safer arrangement-a complete catwalk.
"A lot of times you want an inspection walkway system if  the bridge is carrying a power or utility line, which was the case here," said Cooper B-Line - GS Metals district manager Tom Thies, who serviced the project. "You need good traction so inspections can be done easily and safely."
Inspection walkways also become important as highway bridges age and deteriorate. According to Frank, this was a long-term consideration for the KDOT in the design of the bridge. In addition to routine annual inspections, the KDOT does an in-depth inspection of highway bridges every 10 years.
We felt that a catwalk system would save time and money in the future," Frank said. "Inspections near the deck level (upper level), where water problems or cracking may become a problem, weren't possible with the old walkway system."
With the new Heavy Duty GRIP STRUT catwalks, the upper deck portion of the bridge is now easily accessible from the main access walkway, a 30-inch-wide walkway that runs the length of the bridge. During construction of the different bridge sections, construction personnel found the completed walkway useful; they used it to store tools, set down bolts and other accessories and access other areas of the site.
This innovative GRIP STRUT walkway configuration creates a win-win situation for everyone: building owners are now able to use roof space to generate revenue, and the cellular companies can save time and money associated with building a free-standing cellular tower.
Features of Heavy Duty GRIP STRUT
Cooper B-Line - GS Metals Heavy Duty GRIP STRUT planks and walkways feature an aggressive serrated surface that grips soles securely in all directions, providing maximum slip protection under practically all environmental conditions. It is ideally suited for all working surfaces where rain, snow, grease and mud create slippery or hazardous conditions.
The open diamond design lets liquids pass through to keep the grating clear and sheds slip-causing debris. Heavy Duty GRIP STRUT grating is designed especially for applications requiring greater load capacity or longer span ability.
Traditionally, bridge inspections are accomplished with "snooper" gantries, scaffolding and vehicle-mounted booms and cranes that can cause both traffic flow and safety problems, making the inspection process time-consuming and expensive. With Heavy Duty GRIP STRUT walkway systems, workers can safely access virtually every part of the bridge using strategically-placed planks equipped with side channels and handrails.
"The turned up pans (side channels) were something that definitely made the walkway seem safer," Frank said. "You would have to intentionally fall off of it. On the old walkway, you could rub the rust off as you walked and almost slip under the railings. You felt really unsafe."
Before safety grating walkways were specified as rooftop walkway systems, solid steel troughs covered the PVC piping that held the cables. But, a major problem with solid trough was that it collected extreme heat during sunny weather. Also, the solid steel surface of the troughs was smooth and slippery and was unsafe for maintenance personnel who had to walk on it. In contrast, GRIP STRUT features an aggressive surface that provides traction in almost every condition, while still protecting the cables and rooftop surface.
"We're really pleased with how it turned out. We affectionately call it the 'Cadillac of catwalks,'" Frank said. "You don't think about falling when you walk on the new system, with the double railings and toeboards. The main walkway is so wide it almost meets ADA guidelines!"
For more information contact Cooper B-Line - GS Metals CORP., 3764 Longspur Road, Pinckneyville, Illinois 62274. Phone: 800-851-9341 or 618-357-5353. Fax: 618-357-3605. E-mail: webmaster@cooperindustries.com.
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