New Flexible Power Pole Prevents Cascading Collapse of Power Lines

by Alex A. Kecskes

The metal poles carrying power lines across the country are big, round and sturdy--some up to 12 feet in diameter and soaring100 feet high.

But extreme ice and wind can bring down even the sturdiest of transmission poles. When one of these poles falls, it can pull others down to produce a domino of collapsing poles—resulting in lights out for the city they serve. Many areas in the open countryside have long stretches of transmission lines. Here, one fallen pole can take down 10 miles of poles.

Iowa State University's Jon "Matt" Rouse and Casey Faber have designed a more reliable and cost effective power pole, one that resists cascading failures. Their new, hinged poles can be installed without the use of cranes, making them easier to raise. When exposed to extreme load, they can be repaired rather than replaced. The pole's ability to resist cascading failures means expensive dead-end structures would no longer be required. Simply put, the new poles deform rather than collapse.

The nominally rectangular pole incorporates a built-in hinge near the base. Metal plates on either side of the hinge act as replaceable "structural fuses," stretching and buckling when the pole is subjected to extreme loads. In this way, the pole deflects the stress, shielding the rest of the pole from damage. Tendon cables running up and down the inside of the pole resist stretching and work to keep the pole upright. When the pole is stressed to the point of failure, the fuses bend, the hinge pivots, the interior cables tighten and nearby poles pick up a portion of the load.

With the country poised to develop new sources of energy—like wind, solar and geothermal—transmission lines will be crisscrossing many extreme weather areas. New power poles like these will help ensure the power moves uninterrupted to its many destinations.

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