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Behind Utility Pole Inspection: How Are Poles Made?

POSTED BY: Ashley Little on 07.28.2015

existing_pole_truss-154000-editedAt Alden, we have audited millions of assets during utility pole inspections. Assessing poles for violations and safety concerns, surveying their locations, as well as counting and recording attachers, are all vital parts of keeping service flowing safely and consistently to customers. Today, we answer a reader question: How does the ubiquitous 40-foot piece of pine, concrete or iron come into existence, and what is the cost?

Wood

The way a utility pole is created depends on its material. Wood poles, perhaps the most iconic and recognizable of all utility poles, are also the oldest type. Dating from the dawn of the telegraph, you would have started seeing wooden poles dotting the American landscape around 1844.

How are they made? Wooden poles begin life as trees (typically standard tree varieties like Southern Pine, Douglas Fir, Western Red Cedar and Red Pine), which are harvested, laid on a flatbed truck, and hauled to a mill yard. They are peeled of their bark, then smoothed via lathe to an even circumference. Next, they are cut to standard sizes (typically 30 feet and up in 5-foot increments), have their circumference and lengths measured, and are marked on the ends with identifying information. Finally, the wooden poles are kiln-dried, chemically treated to repel insects and strengthen them against moisture and rot, and then shipped to a yard where they patiently wait for their time in the field. Cox Wood Industries has a great video available that shows the utility pole manufacturing process from start to finish.

How much do they cost? Prices vary, but according to American Timber and Steel a 40-foot treated utility pole ranges from between $400 and $600 depending on its class type. So, a 60-foot pole would typically cost between $1700 to $3000.

Concrete

Concrete poles have been gaining popularity in the last decade for their durability in challenging environments, their high density to low weight and their strength.

How are they made? Spun concrete poles are made in a mold and pre-treated with a release agent so the material does not stick. Wet concrete is placed into the mold, then the top half of the cylinder is put on, and bolted in place. High-tension steel cables are inserted to add strength, and then the action starts. The mold with concrete inside is spun, allowing centrifugal force to compact it smoothly into a hollow cylinder. The mold is released, the concrete is cured and the pole is ready to be erected. For a closer look, watch as a concrete utility pole is made in India.

How much do they cost? StressCrete, a company based in Burlington, Ontario, Canada with a plant in Tuscaloosa, AL, charges $375 for a 40 foot, class 3 pole and $350 for a 40 foot, class 4 utility pole.

Ductile Iron

Strong, recyclable and with less impact on the environment than wooden poles, ductile iron poles are becoming the sustainable choice for many municipalities. This type of iron is corrosion-resistant, offers 80+ years of service, and, unlike wood, is woodpecker, bear and insect-proof.

How are they made? Ductile iron poles are cast of metal heated to 2200 degrees Fahrenheit. Made liquid, it is poured into a rotating metal mold. It takes about 30 seconds to create the pole and another 15 for the molten metal to cool to a solid. The iron pole is removed from the mold and the process starts all over again—a manufacturing marvel that is created start to finish in a quick 60 seconds flat. Birmingham, Alabama manufacturer Seamless Pole has a fascinating narrated video that details the whole process of creating an iron utility pole.

How much do they cost? Iron poles have an initial cost that is higher than concrete or wooden poles, but their longevity and easy maintenance makes their lifetime cost about 20% cheaper and their lifespan about twice as long as a wooden pole.

Right Pole, Right Plan

Whatever the right pole type for your business, when it ends up in the field, it is up to the owner to maintain its health and efficiency. So no matter the pole type, periodic utility pole inspection conducted by a thorough partner dedicated to collecting the right data and then leveraging that data into action and processes designed to keep you in control of your assets—whatever they are made of—is incredibly valuable. So, choose wisely in terms of poles, but also choose wisely in terms of an infrastructure asset management partner. Your poles, and your customers’ uninterrupted service, depend on it.

Share with the class: What pole material works best in your service area? Add your thoughts in the comments below.

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