Are your lighting poles putting you at risk?

We see them every day and take them for granted. They support the lights that illuminate your football, baseball, softball, and soccer fields. They help light tennis courts, parking lots, and sidewalks. They’re all around us and if they’re doing their job correctly, you may never think of one twice. But are your lighting poles putting you, your staff and visitors at risk?

One of the most overlooked aspects of a comprehensive facility maintenance program is the proper inspection of your lighting poles, but before we discuss the methods available to perform these inspections, ask yourself or your staff the following …….

1. When was the last time we inspected our light poles?
2. Did we keep written notes and develop records of the inspection?
3. Did we just give them a visual inspection, or did we use any type of non-destructive evaluation method to find potential problems the eye cannot yet see?

The answers may surprise you ….

Looking Back

Many of the keys to maximizing the life cycle of a pole occur before a single light is ever turned on. When your poles were initially installed,

1. Did a qualified Professional Engineer calculate the applied loads, design the pole and foundation?
2. Were the poles originally designed and manufactured to correctly calculated loads, and with good quality standards meeting or exceeding current industry procedures?
3. Were the poles purchased to meet standard, recognized structural code with appropriate load and strength safety factors, or were they sold as a general “commercial grade” design, whatever that means?
4. Did a responsible and experienced contractor install the pole correctly per the Architect or Engineer’s instructions?
5. If the answers to any of the above are “No” or simply, “I don’t know”, then consideration should be given to a comprehensive inspection program to assess and remediate any defects in your lighting poles.

Photo 3- Statically Cast Concrete Pole w/ cross sectional moment capacity failure

A Growing Trend of Pole Failures

Most pole failures tend to be catastrophic with the final result being that both the pole and the lighting system end up on the ground. Fortunately, most failures to date have only resulted in property damage, but there have been several occasions where the failure of a pole has caused both injury and death, a situation that everyone wants to avoid at any cost.

Recently there has been a growing trend of poles failing due to corrosion, steel fatigue, weather and other key factors, including improper initial design and/or installation. In Texas alone, there have been six recorded catastrophic failures of lighting poles at public schools in the just the last 120 days and the trend line appears to be growing exponentially. A number of other poles were found to have structural deficiencies, but these were discovered prior to catastrophic failure of the pole.

An Investment in Inspection

To mitigate and help prevent failures, a currently installed lighting pole (like any other structure on your property) should be routinely inspected by a qualified firm with the technical experience necessary to evaluate the specific potential problems associated with poles. These inspections should focus on detecting and evaluating:

• Evidence of deterioration/corrosion both internally and externally on the pole;
• Evidence of metal fatigue due to cyclic loadings (such as wind induced vibration);
• Poor quality welding not in accordance with American Welding Society standards;
• Photo 4- Steel Pole w/ internal corrosion & likely fatigue related issues.
• Photo 5 – Steel Pole with split seamweld
• Evidence of weld failures (pole shaft to base plate, poles shaft seams, access openings);
• If equipped with climbing facilities, are the steps, cables, etc. in good condition;
• Evidence of foundation problems (Does the concrete show any signs of failure?)
• Are the anchor bolt nuts tight? Are the anchor bolts in good condition?
• Is there proper “weep hole” drainage of any moisture buildup on the interior of the pole?
• Are there any other installation issues (unauthorized weldments or modifications not originally considered in the design)?

A combination of visual inspection and non destructive Ultrasonic and Magnetic Particle testing methods should be utilized in order to provide the most comprehensive results. Ultrasonic scanning is used to measure wall thicknesses of the pole shaft for determination of metal loss and both Ultrasonic (UT) and Magnetic Particle (MT) testing can be utilized for non-destructive evaluation and locating weld defects. They can also be used to locate cracks in steel due to fatigue related issues. These procedures should be accomplished by ASNT (American Society for Nondestructive Testing) certified technicians. A Professional Engineer, experienced in the design, fabrication, and installation of poles, should evaluate all of the results and provide an assessment of each pole installation. With routine physical follow-up inspections (every 3-5 years depending on the initial baseline inspection) many structural problems can be identified and remedied before they progressively lead to catastrophic failure. Purchasing New Light Poles? If your plans include the design of a new facility or you have already made the decision to replace your light poles and lights, there are several factors that should be taken into consideration from the outset.

Photo 6- Steel Pole w/ Anchor bolt failure likely due to fatigue

1. 1) Utilize an experienced, qualified Engineering firm with structural engineers on staff to develop the performance specifications needed for the design of the poles. The initial investment may be marginally greater but the determination of the appropriate structural design codes, appropriate wind zone, and the calculation of the loads the poles must sustain is critically important. Other structural attributes such as deflections, general fatigue resistance details, coatings, etc. can also be identified within that performance specification.
2. Once the specifications for the pole, lighting and foundation have been developed by a knowledgeable Engineer, make sure that the pole system is then designed to those specifications by a Professional Engineer and the pole assembly is accomplished per the pole manufacturer’s recommendations. Foundations should be properly installed per the Foundation Engineer’s details.
3. No pole is maintenance free and deterioration will inevitably occur. Once the poles are installed, plan to engage a qualified company to provide periodic inspections of the installations (perhaps on a 3-5 year cycle) to make sure your poles continue to perform as they were designed to do, and most importantly, continue to be safe.

Photo 7 – Failed Concrete Stub Base Pole