Structurally Sound?

Don't let your towers end up the forgotten element of preventive maintenance.

Transceiver? Check. Power supply? Check. Surge protector? Check. The list of equipment to inspect during routine maintenance is long. Much of the regularly inspected equipment that forms the wireless engineer's checklist is housed at the foot of a tower in a shelter where problems are likely to be less catastrophic. But the tower, a crucial element of the network, is often the last to be checked and sometimes is overlooked completely.

"It's like the saying goes, 'Ignorance is bliss,'" Ron Rodriguez, Centerpointe vice president of development, said. "When it comes to towers built prior to 1995, operators don't inspect the tower until there is a problem."

A failed tower can be deadly to a wireless network, yet towers aren't inspected nearly as often as other equipment. Why?

Before the tower-consolidation movement of the late 1990s, providers owned their own towers and dedicated entire crews to their repair and preventive care. Call it pride of ownership or overprotection, preventive maintenance was part of every engineer's schedule. Today, engineers conduct spot inspections of towers, but the majority of their time is spent planning expanded-coverage networks and adding capacity. With this shift in priorities comes a more relaxed approach to structural maintenance.

Rodriguez contends that older towers are often treated like the young ones. But as these 10- and 20-year-old towers age and the need for capacity grows, the problem of weakened and weather-worn towers will intensify.

"Tower inspections on older towers are mostly done as an afterthought. Engineers find out the strength of a tower only when it comes time to put another carrier on it," Rodriguez said.

Towers should be inspected an average of every two or three years, according to Rodriguez. Currently, regular inspection for towers built prior to 1995 is done about every 10 to 15 years, or eight to 10 years for older monopoles.

Many tower inspections are done visually. An inspector usually will check ground-level supports, bolts and paint degradation, but not climb the tower. Corrosion at the top of the tower and eroding metal interiors often go unnoticed.

Inspection Tips
An important exercise for any tower inspection is to review the original tower drawings. For older towers, this may be difficult, as drawings are often lost or destroyed. In these cases, a new tower map can be created easily and accurately through a tower-inspection or management company.

The purpose of having a tower drawing is to ensure you have factual information about the age, structure and capacity of a tower. Even if you are leasing tower space, you shouldn't be afraid to request the tower drawings or inquire about maintenance records. You also should ask whether physical inspections, not just remote inspections, are done regularly.

"The best way to see what kind of maintenance a tower needs is to get out there and climb it. It's best if you can put your hands right on the tower," Rodriguez said.

Because towers can rust from the inside out, you should consider conducting an ultrasound test to determine if there's any interior corrosion. Replacement of a bar or two now is always better than rebuilding an entire tower later.

One of the simplest items to check on a tower is the guy wires and connections. Always check the condition of the bolts. Check the tension of each line and make sure the foundation is adequate.

There are ways of checking a tower's foundation with detailed accuracy. Stress-wave technology can ascertain the depth of a foundation, giving you a better sense of its load limit without drilling.

Some experts suggest you should look for rodents. If there is a preponderance of wildlife living on or around a structure, there is a greater likelihood of weak ground caused by burrowing animals.

Keeping in Shape
The first step in maintaining your tower is regular and thorough inspections. Once a regular maintenance schedule is put in place, it's time to move into action.

Here's a simple list of things you can do to keep your tower and equipment in tip-top shape.

• Protect with paint. A tower should be painted regularly to keep water from corroding it. Sealant can be used around joints to ensure protection against the elements. In cold areas and places with severe weather patterns, you should schedule painting during the spring months. Never paint in the summertime. As the temperature climbs, the tower's metal expands, causing paint to shrink and crack when it contracts during cooler temperatures.

• Care for your cable. Whether you rent space or own your own tower, you'll want to keepyour coax healthy. Larry Eveslage, NK Cables vice president of marketing, said coax should be changed every 10 to 15 years. The thicker the cable, the longer it's likely to last. Half-inch cable should be checked more frequently than 2¼-inch cable. Often, the signal strength will provide an early warning that your cable needs to be replaced.

Vandals, inappropriate installation and weather all are determining factors in cable maintenance. Cable can be the victim of target-practicing vandals. If a bullet grazes your cable, it may result in a significant signal loss over time. Sweeping the line is often the first line of action when doing site maintenance.

• Correctly connect. Connectors are a common culprit in loss of signal strength. Eveslage said connector longevity is not yet up to par with other tower components, such as antennas and cable, but it's getting closer. To extend the life of your connectors, make sure to apply the correct amount of torque and sealant upon installation. This will help maintain a strong, leak-proof connection.

• Invest in instruction. Proper installation of all tower components is key. Many tower and consulting companies, as well as vendors, offer installation instruction and certification to ensure the best maintenance of your equipment. Not all providers take advantage of this benefit, according to Eveslage. However, the more you know about the equipment, the better it will pay off by reducing future maintenance costs.

• Love your lights. If a safety light seems weak or slow, don't wait for it to go out. Replace your bulb regularly to prevent outages. In most cases, if a safety light goes out, a site manager has 15 minutes to write a report on the defective light or risk an FAA fine for endangering the flying public.

Today, TWR offers a ground-level meter-system light, which is becoming increasingly popular with engineers. TWR's lights feature form-C, dry-contact terminal blocks and are wired to give information to the engineer on the ground instead of just at the source. Power mechanism, intensity and flash-tube information also are available without climbing the tower.

Bottom Line
Even though tower co-location and consolidation are on the rise, new towers will continue to sprout up. Frequent inspection, better maintenance and vigilant engineers will be imperative regardless of tower age or ownership. As Rodriguez pointed out, bottom-line-conscious providers will be wise to understand the basics of tower maintenance.

"If I had $40,000 of equipment someplace, I'd sure want to keep an eye on the maintenance going on there," Rodriguez said.