Better Roads Digital Magazine
Issue link: https://read.dmtmag.com/i/85916
Climbing Bridge Engineers on ropes doing specialized structural inspections ridges that were once inaccessible by tradi- tional methods can now be thoroughly in- spected by engineers climbing and rappelling down the structures.When the floodgates of a large dam in Folsom, Calif., unexpectedly failed during a routine opening, the U.S. Bureau of Reclamation and the Army Corps of Engineers (COE) – the dam owners – mobilized quickly to inspect the remaining gates for distress. However, the location of the main structural components – perched on the dam spillway about 250 feet above the base of the dam – was hampering the abilities of engineers to access the critical areas. The only way to quickly address the problem was to rappel down the structure so climb-trained engineers from COE (from across the United States) and the Of- fice of Structure Maintenance and Investigations at the California Department of Transportation (Caltrans) were brought in. For two weeks after the 1995 inci- dent, Caltrans engineers assisted COE with evaluating the remaining dam gates. "Extensive investigations, evaluations and materials testing were completed with a minimum of expense and effort," explains Stephen Sahs, senior bridge engineer, emergency response and bridge coordinator/ fracture critical technical access coordinator/seismic specialist, for the Office of Struc- ture Maintenance and Investigation at Caltrans. The use of climbing techniques – i.e. rope access – for bridge inspection has proven to be a valuable tool for the investigating engineer or technician, Sahs adds. B "In some cases, climbing is the only effective means to gain access to certain bridge elements," he says, adding that the techniques have been proven to be "an economical and effective for a variety of routine and specialized bridge inspections." Caltrans bridge engineers have historically used heavy industrial rope and rigging techniques to gain access for bridge inspection. The rigging was done by either Caltrans' Bay toll bridge paint crew or private contractors following the standards of the construction industry. Now, rope access techniques are used in California as an alternative means of gaining access to bridges and structures when other conventional methods can- not be used due to inspection equipment limitations and/or when traffic is greatly impacted. More than 50 bridges in Caltrans' jurisdiction have been identified as structures where climbing is the only means avail- able to perform structural investigations. "The traditional uses of under bridge inspection trucks, life equipment and rigging are economically and practically limited by bridge size, structure type, traffic demands and support costs," says Sahs, who authored the paper Climbing Techniques for Bridge Inspec- tion, which was presented at the International Bridge Management Conference. (For a downloadable PDF of the paper, go to http://www.betterroads.com/climbing- techniques-for-bridge-inspection/.) Sahs says that in some cases, bridges have become Better Roads May 2012 21