Would you rappel down the St. Louis Arch?

[Deberg_1990]

They will be looking for people to inspect and wash it soon. Rappeling was determined to be the best method.


http://www.kansascity.com/2012/09/25...-cleaning.html



St. Louis Arch is sound, but cleaning will present challenge
By NICHOLAS J.C. PISTOR
St. Louis Post-Dispatch
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ST. LOUIS -- Stains on the outer surface of the Gateway Arch may be caused by the welds that hold the 630-foot monument together, and crews should rappel from the upper reaches for a closer look, a new engineering report suggests.
The report says the Arch is structurally safe but needs further attention to protect its beauty and address growing signs of age.

Its recommendations effectively create a new extreme sport in which trained technicians would become monument mountain rappellers. They would strap themselves on industrial “choker hitched ropes” to descend the long curved legs of the unique structure.
There is no timetable for the inspection or ultimate cleaning.

Corrosion and stains visible on the surface and interior are cosmetic and don’t threaten the structure, according to the report by engineering firm Wiss, Janney, Elstner Associates, in Chicago.

The firm said that encircling the Arch legs with “belt-and-choker-hitched” ropes would allow workers close-up access without damaging the stainless steel skin. A system of redundant hitches would prevent technicians from experiencing “a dangerously large swing should they be blown by the wind.”

The Arch would have to be closed while this operation is performed, the report states. It would take an estimated five days and would surely become a tourist draw of its own. The report warns that it would attract “significant media attention” which could delay the work and “detract from the primary focus of performing the work safely.”

A news release by the National Park Service says the Arch is in “excellent structural shape.” Arch officials have been investigating corrosion and stains for more than six years.
The most recent study is the second in a four-step process, according to the park service. The next will include the rappelling for “close-up testing of the welds to determine the best method of cleaning the metal and stopping the streaking at its source.”

Frank Mares, the deputy superintendent of the Jefferson National Expansion Memorial, said this step can “only proceed after funding is secured.” The estimated cost is $180,000, including crew planning, preparation, and travel time.

The engineering firm studied ways to access the upper reaches, ranging from scaffolding to cranes. It ultimately decided that rope access was best. It did not offer a timeline for the final step, a full cleaning. A 2006 corrosion report recommends that the skin be cleaned by 2016.

Officials said the structural analysis and cleaning are separate from — and would not compete for funding with — plans to reshape the grounds surrounding the Arch.

“The Arch may be a little discolored in some places, but we are now certain that it is part of the aging process, and we will work to keep this one-of-a-kind structure in the best shape possible for future generations,” said Tom Bradley, its superintendent, in a written statement. “It may take some time to get up there to clean it, but we will get it done.”
The surface of the monument, completed in 1965, has never been cleaned.

No cost estimates for cleaning are included in the report. A previous study, however, noted “the initial cleaning will be expensive due primarily to access requirements, but a reusable means of access should be designed as part of the cleaning procedure.”