New tower regulations coming
Sep 1, 2001 12:00 PM, Broadcast Engineering
New TIA/EIA tower standards A new standard for steel antenna towers and antenna supporting structures is being finalized. The standard, called Revision G, will replace the current rules, called Revision F, which many of today’s towers are operating under. The changes in the standard are primarily driven by new knowledge of wind and load factors on tower and similar structures. Also, as broadcasters are intimately familiar, local zoning and national building codes often impact plans to construct towers and new solutions are often needed. The current standard (REV. F) is under review by a committee of volunteer professionals primarily tower engineers, and other communications product engineering consultants. The proposed new standards are expected to be made public after the first of the year. The EIA committee is likely to vote on the new standard sometime next year. How will Revision G affect tower design? The key differences will be noticed by tower designers. New calculations will change how loads are computed. For instance, the current standard calculates wind loading based on Fastest-Mile wind speed based on history and distance. The new standard will calculate wind loading according to three-second gust wind speeds. This means that a 50mph wind speed is not considered the same as a 50mph three-second wind speed. The new standard’s goal is to more accurately reflect the load a tower might encounter. The new standard is also likely to include a mandatory ice load factor. Tower location will determine if the ice region calculations apply. Will you have to modify your tower? Maybe. If you plan on adding antennas or increasing the load, you may have to bring the tower into compliance with Rev G. If your tower currently meets today’s criteria and you’re not adding anything, additional changes are unlikely to be needed. What about new towers? If you’re planning to build a new tower soon, you should work closely with your tower designer and contractor. While the standard isn’t official now, a competent engineer or company can help you determine if your tower is likely to meet the new criteria. This could help protect your tower investment by ensuring the structure meets both today’s and tomorrow’s requirements. Brad Dick Editorial Director Editor’s note: PiRod has a brochure reviewing the proposed new regulations and how they may impact broadcasters. You can obtain a copy by contacting the company at: 219-936-4221 or www.pirod.com.
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