Inspection team goes to new heights.
In the past, it was difficult or impossible for structural engineers to inspect some portions of large steel or concrete structures because they could not get to the areas that required inspection. To get a floating plant or a crane to move inspectors to the required inspection positions on the structures was prohibitive because of the cost and was sometimes impossible to achieve. Eight years ago, two USACE structural engineers, both avid mountain climbers and accomplished structural steel designers, suggested that rope access techniques could provide safe access to inspect large steel structures. Since then, six more structural engineers from the St. Louis District have achieved their certification, bringing the total to eight personnel who are qualified to perform rope access inspections. There are only a few USACE districts that have engineers certified to conduct these types of inspections.
The structural inspection team performs rope access, rather than using more traditional methods like scaffolding, cradles, or equipment (scissor lifts, cherry pickers) for three primary reasons: it is safe, versatile, and economical.
First and foremost, it's safe. A two-rope system is used, with one rope serving as the working line to support the worker and the other rope acting as a safety line to provide complete independent redundancy. This is similar to the way climbers ascend the steep rock faces of mountains, except they use a single line.
The method is versatile, allowing the inspector the freedom and mobility to move around more easily than other methods. Regulations require inspectors to get "up close and personal" with structures. The rope access technique allows them to get close enough to look at critical areas closely, take pictures, and perform other inspection tasks they wouldn't otherwise be able to do.
The rope system is also economical because it can be installed and dismantled quickly. This allows inspection teams to move from one portion of the job to the next more quickly than using other methods. By using the rope access technique, inspectors also minimize many of the mobilization and setup costs associated with the other methods.
The team has not used their expertise to benefit the St. Louis District alone, though. They've also performed inspections for a four-span railroad bridge at the Holston Army Ammunition Plant in Kingsport, Tennessee; at tainter gates on dams in the Kansas City District; and at tainter gates on Missouri River dams for the Omaha District.
After the record-setting floods on the Missouri River in 2011 and given the elevated pool levels that the dams withstood, the Northwestern Division and Omaha District of USACE were eager to have the six dams on the main stem of the river inspected as soon as possible. The St. Louis District rope access team was called on to perform this task, which primarily encompassed 95 gate structures at the six dams. The timeline to complete the work was tight, so they reached out to certified rope access technicians of the Philadelphia and New England Districts. Engineers from the St. Louis and Philadelphia Districts inspected the Garrison and Fort Randall Dams together. This established continuity between the two teams, making sure that they were addressing the same issues and noting discrepancies or concerns in a similar manner. The teams split up the remaining work, with the St. Louis District taking the Big Bend and Oahe Dams and the Philadelphia District taking the Gavins Point and Fort Peck Dams. A certified inspector from the New England District also assisted at Fort Peck.
To the relief of the Northwestern Division and Omaha District, no major deficiencies were discovered on those main stem dams. The quick collection of data was critical, said a spokesman for the Northwestern Division. The floods were a record event and USACE needed to find out as soon as possible how the dams performed and how they would perform during the next flood season.
The St. Louis District team has expanded in the following significant areas:
* Types of structures inspected.
* Composition of the team.
* Variety of customers served.
* Use of partnering concepts with other rope access-trained districts.
The team's willingness to share the knowledge of this type of inspection, coupled with the willingness and planning to inspect new and larger types of structures, reflects the regional and national stature of this effort.
By Mr. George E. Stringham
Mr. Stringham is a public affairs specialist with USACE, St. Louis District.
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|Author:||Stringham, George E.|
|Publication:||Engineer: The Professional Bulletin for Army Engineers|
|Date:||May 1, 2012|
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