At 3,000 feet long and almost 1,000 feet high the New River Gorge Bridge is the largest single arch span bridge in the world.
The problem was that de-icing salts were causing the joints in the bridge to corrode. Built of Corten steel, the bridge was supposed to develop a patina of protective rust but the salt and design of the joints were causing the joints to develop extensive pack rust. Specialty Groups, Inc (SGI) job was to ultra high pressure clean these joints to remove the pack rust and salt to inspect how much damage had been done. We also used high pressure water (3000 psi) to clean the salt from the remainder of the structure both inside and out. The West Virginia Department of Transportation had changed the type of de-icing material used to prevent further damage.
SGI was responsible for designing and installing the access systems to safely complete the work using a combination of five different systems to access the bridge. One was a mother deck that rolled on the parapets with smaller man baskets hanging from a monorail that could drop into tight areas. Another was using one of the largest bridge inspection trucks in the world to access the inner areas of the upper deck truss system. Another system utilized a modular deck system consisting of 2 separate platforms over 40 ft long, with climbing motors to access the exterior of the bent legs, another using 2-45 ton cranes to drop man baskets into the bent joints and other areas and finally, outfitting a crew with miners lights and other equipment to clean the interior areas of the arch and bent legs.
We cleaned 2.5 million square feet, starting the wash on April 1 and finishing by July 31. We installed 8,000 feet of water line with a connection point every 200 feet. Over a million gallons of water was used in the process.