Guy Anchor Program
Guyed tower support structures create a system that encourages accelerated galvanic corrosion of guy anchors. Current industry grounding standards inadvertently create a corrosion cell by placing dissimilar metals in close proximity: copper grounding rods and zinc-coated anchor shafts. The rate of corrosion is also affected by moisture, temperature, aeration, electrical conductivity and pH of the soil. Many guyed towers are at risk of failure, long before the end of their design life.
PB Architects has investigated guyed towers across the United States. As a result of our findings we've created the Guy Anchor Program to evaluate, protect and replace corroded guy anchors.
Identification
The first step is to identify, assess and prioritize potentially at-risk towers based on:
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Upcoming overlay or site modification activity
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Importance of the site to network integrity
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Site revenue generation
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Age of the tower
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Soils classification
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Proximity to other towers with confirmed corrosion
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Proximity to sources of stray electrical current
Inspection
PB Architects has created a comprehensive procedure for anchor inspection that emphasizes the safety of the crew and protection of the tower and other nearby structures at every stage of the analysis and excavation of the guy anchor shafts. Anchor inspections are conducted by trained personnel, using methods that have already prevented tower collapse and saved lives.
Protection
Replacement anchors are fitted with a cathodic protection system to slow the rate of corrosion, protecting lives and network investment. Existing anchors can be retrofitted with the system during inspections, ensuring extended anchor life.
Replacement
PB Architects has proven experience with cost-effective engineering and project management for the replacement of deteriorated anchor systems.
Anchor Study Program Findings
In 2004 PB Architects identified the 20 high-risk towers in our client's network of 1,600 facilities. As shown below, 25% of towers required anchor replacement.
Sites |
20 Towers Targeted (selected from 1600 facilities) |
|
20 |
Surface investigations; cathodic protection installed |
|
10 |
Sub-surface investigations; cathodic protection installed |
|
2 |
Scheduled anchor replacements |
|
2 |
Emergency anchor replacements |
|
1 |
Anchor failed during inspection |
It’s a matter of
time…
- Towers are a critical part of wireless network infrastructure.
- There are over 71,000 towers registered with the FCC. It is estimated that over 50% of guyed towers located in the central USA are exposed to high levels of corrosion.
- Surface inspections of guy anchors typically do not reveal the full extent of the damage.
- Towers with a design life of thirty years may not make it to even half that age – towers have been identified that require anchor replacement after only eight years of service.