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02/01/2005
OSHA Relations Committee Update
Alert reader John Hettish from Middle Tennessee Two-Way brought to my attention what I believe is some forward progress on addressing antenna mast safety climb systems. A few months ago I wrote an article about antenna mast safety issues.
The system is a rope grab-like assembly in the configuration of a cable safety climb assembly. There is a top anchor, guides or keepers along the climbing route and a base/tension adjustment assembly at the bottom. The key element is the non-metallic composition of synthetic materials that comprise the rope, an Aramide Fiber Cable. This rope is not your grandmother’s hemp. This material is purported to be RF invisible and is not suppose to threaten, degrade or influence signal propagation in any way.
Questions remain about the possible long-term effects that RF radiation exposure will cause to this synthetic rope in such close proximity to the radiation source. Also, what effects, if any, will ice have on the signal propagation or heat effects on the rope when surrounded by ice (possibly cooking it). Durability under these severe service conditions and proper inspection and testing procedures are still areas that I need to better understand. Certainly, cautious and conservative replacement intervals will need to be established, whether retro installations are possible, and a host of other issues.
I’d eventually like to review empirical data on real-world studies of signal propagation with and without ice accumulation, during high wind and at various power levels from one-megawatts to five-megawatts effective radiated power. Some broadcasters may be reluctant to install something in the aperture of their antenna without the blessing of the antenna manufacturer.
The transition from the top of the tower to the mast and back will require site-specific procedures to maintain 100% tie-off during ascent and descent.
As I learn more about this product, I‘ll share it with you. While this may not be a universal solution, it should be remembered that complex issues require refinement over time to meet the expectations and needs of the users.
I’m glad to see movement in this area.
Don Doty serves as Chairman of the NATE OSHA Relations Committee as well as Vice Chairman of the Association. He is the Vice President of Doty Moore Tower Services LLC of Cedar Hill, Texas and can be reached at 215-631-1300 or don.doty@stainlessinc.com
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