HOW TO AVOID THE 12 MOST COMMON CAUSES OF BROADCAST TOWER LOSS
by Douglas Federau
'If it ain't broke, don't fix it' applies to the way many owners view the more than 20,000 broadcast towers dotting the nation's landscape. Unfortunately, there is a tendency to ignore towers simply because they require less attention than the more technically intensive facilities involved with radio and television broadcasting.
There is also what can be called the 'We're-insured-so-why-worry' attitude.
Even if something goes wrong, the safety net is the insurance policy.
Controlling loss is at a critical point. Tower construction costs are escalating, and so are the insurance claims. The prudent business approach is to eliminate wherever possible the opportunity for damage to occur.
A tower that is out of service sets into motion a chain of events resulting in loss of income, audience share, and advertisers, notwithstanding the disruption of the station operation.
There are 12 common causes of broadcast tower loss. A review of insurance claims points out the fact that virtually all losses fall into these dozen categories. By being familiar with the causes, it is possible to minimize the risk of having a tower either damaged or destroyed.
1. INADEQUATE PLANNING AND ENGINEERING. It is relatively easy to overcome the planning and engineering problems. The first step in the planning process is recognizing that weather is the main cause of tower loss.
Wind, ice and lightning account for more than 75 percent of broadcasters' losses. Tower owners and chief engineers should focus attention on gaining an in-depth understanding of climatological data in the areas where their towers are located.
Once the potential for weather extremes is recognized, steps can be taken to install the equipment necessary to minimize the possibility of loss. Basically, the type of tower, quality of construction, and installation must be appropriate for the topography and able to withstand the climatological extremes in the area where the facility is located.
2. Lightning. Lightning accounts for approximately 20 percent of all tower property claims, and the higher the tower, the greater the possibility of lightning losses. Here is a checklist to help minimize tower damage by lightning.
- Lightning rods should project well above the tower beacon. Use binoculars to verify that the rods are in place and in good condition since severe lightning hits may vaporize them.
- Guy wire anchor points should be grounded to the nearest radial by copper strap.
- For grounded towers, at least four 10-foot rods must be bonded to the tower base and in contact with the groundwater table. Soil must be tested to determine conductivity.
- For insulated towers, the ball gap should be clear of debris so that the bare metal is exposed.
- Insulated towers should have a static drain choke connected between the feedline and the station ground.
- Insulated towers should have two 12-foot loops in the feedline between the tower and the transmitter housing.
- Cadwelding the connections is recommended.
- All tower attachments should be grounded to the tower, and these connections should be inspected annually, since poor connections can cause severe harm to equipment.
- Power lines must be protected with surge arrestors and line chokes.
- Phone lines should be protected with MOVs (Metal Oxide Varistors).
- In lightning zones 6 or higher, lightning dissipation systems are highly recommended.
It is prudent to have all grounding and lightning dissipation work be done by a professional lightning-abatement firm.
3. ICE. Two types of ice cause problems. Rime ice is similar to what is found in a refrigerator. It weighs about 17 pounds per cubic foot and is quite porous. Glaze ice is different, and occurs only in certain geographic areas and elevations where the temperatures drop below 32 degrees. It is quite common in lower latitudes; it accumulates when there is a slight drizzle. This type of ice has a density of 54 pounds per cubic foot.
A failure to install de-icing equipment results in excess weight and will cause increased wind resistance, resulting in possible tower failure. A single icing episode can produce damage to the tower, antenna, feedline, and associated structures simultaneously.
- Ice cracker cones are effective in protecting the guy wire grips.
- Ice bridges protect attachments from falling ice, including transmission lines leading from the tower to the transmitter building.
- Ice shields are inexpensive and effective protection for side-mounted antennas, microwave dishes, beacons, and other tower attachments.
4. WIND. It is impossible to build a tower that will withstand all winds.
Wind damage is the single largest cause of broadcast tower insurance claims in both dollar amounts paid and claim frequency. The most recent release, EIA-E, establishes the minimum wind speeds to which a tower must be built in a particular locale.
Tower construction must take into account both the average winds and the peak winds. Climatologists can provide information on any special or unusual wind conditions.
To prevent wind damage, towers must undergo structural modifications if they do not currently meet or exceed the highest wind load expected. Manufacturers should be consulted for specific recommendations. Tower space is often leased for local telephones, microwave dishes, side-mounted antennas, and so forth without considering the impact of the additional weight or wind impedance on the tower's structural integrity.
- Adding radomes to antennas will reduce the wind load.
- Bundling the transmission lines will also affect wind resistance.
- Maintaining guy wires at the proper tension will keep the tower in plumb.
- Making certain the transmission line hangers are tight will reduce the effects of wind load.
- Know the specific hurricane zone.
5. ADDITIONAL CLIMATOLOGICAL FACTORS. Hurricanes, ocean surge, floods, and earthquakes should be taken into consideration. It is essential to analyze hurricanes and tornadoes in terms of wind speed for which a tower was designed. Reviewing current EIA-E data and requesting a periodic structural analysis of a tower will improve the chances of weathering a storm without substantial damage.
Ocean surge can be a cause for damage to towers located as far as 10 miles inland. Earthquakes will damage towers, particularly those that are guy wired.
The major danger of flooding is the damage it causes to the electrical apparatus in the transmitter building. The cost of replacing the structure and equipment can exceed $100,000. Floating debris can produce tower failure.
6. AN INACCESSIBLE TOWER SITE. Sites are often chosen because of a higher elevation to help reduce the need for additional tower height. These sites are often inaccessible during certain times of the year, making repairs impossible. As a result, the possibility of signal loss is increased. It is critical that both the tower site and the transmission building be readily accessible at all times.
7. INADEQUATE TOWER MAINTENANCE. One of the major problems is a failure to visually inspect and maintain proper logs. Maintenance logs are prescribed by the F.C.C. and the F.A.A. The back-up transmitter, generator, de-icing equipment, lightning dissipation equipment, safety lights, radome, and other mechanical devices should be tested regularly, using an inspection form. A comprehensive inspection will include guy wire retensioning and tower bolt tightening.
This type of preventive maintenance not only solves problems but also may help to identify potential causes of damage.
8. LOSS CONTROL PROCEDURES. An absence of some or all key loss control procedures can result in an unnecessary signal loss. Taking the right steps in advance will help keep the station on the air and minimize down time.
- Utilize an Emergency Restoration Service (ERS).
- Provide for an auxiliary tower.
- Provide for a back-up antenna.
- Provide for an alternative source of power: 1) install an on-site generator; 2) contract for emergency generator use; or 3) use a grid review to obtain power from another direction.
- Have a reciprocal arrangement to share towers with another station.
9. LEASING TOO MUCH TOWER SPACE. With increasing regularity, towers are being used to generate additional income. Tower space is being rented for microwaves dishes and cellular telephones, police, utility company, signal relay, local business antennas, as well as even to competitors looking for an antenna location.
Each addition to a tower affects the ability of the structure to withstand the adverse weather conditions for which it was designed. A structural engineer should be engaged to inspect the tower every three years or when adding additional equipment.
10. INADEQUATE SECURITY. Security is becoming more of an issue, particularly in certain areas where towers and studios are located.
The property should be fenced in, or at the least the road or walkways should have locked gates. Depending where the facilities are located, floodlighting roads, walks, and gates is essential, as well as the building, parking areas, and entrances. Lighting is a major factor in deterring vandalism and other types of crime and reducing the possibility of injury.
The transmission building, the tower base, and guy anchors should all be fenced-if not the entire property. Along with minimizing the possibility of vandalism, fencing provides protection for these key areas from being struck by trash removers or farm equipment. Barbed wire should be added to the fencing around these facilities.
AM towers can cause electrical injury to animals or people, so it is prudent to erect fencing. Also, the effects of RF radiation emphasize the need to control public accessibility to certain areas.
11. OTHER CAUSES OF LOSS. Here are additional possibilities for loss:
- Since transmitter buildings are often located near a tower base, they can be damaged by falling ice unless they have been constructed properly.
- A failure to maintain strobe lights or beacons.
- A failure to execute a waiver for damage to property of others mounted on the tower, i.e., microwave dishes or antennas.
- A failure to install central source security systems, such as smoke detectors, motion detectors, and fire extinguishing systems.
- A failure to implement policies for regular equipment monitoring.
12. MANAGEMENT'S REFUSAL TO BELIEVE THAT A LOSS OF SIGNAL CAN OCCUR. With all the pressing daily issues of running a station, it is easy to neglect fixing the roof when it isn't raining. In the final analysis, neglect is perhaps the major cause of unnecessary loss.
The broadcast signal is the station owner's greatest asset. If the signal fails, the value of the station can decline in a matter of hours. Other stations will instantly seize the opportunity to lure both the advertisers and audience away from the beleaguered station. One's goal should be to act as if the worst will happen and to plan to deal with the worst possible development.
All 12 types of tower loss are based on actual broadcast tower claims. Many of the station operators could not believe what happened to their towers. In hundreds of cases, only one station in the area suffered a loss.
The good news is that most losses can be prevented by proper selection of a location, following construction safeguards, and by undertaking preventive maintenance.