Detecting Foundation Pile Length of High-Mast Light Towers

Presentation imageStatus:  Complete
Report Date:  11/07/2022


Hundreds of high-mast light towers across Minnesota sit on foundations secured by piles embedded deeply underground. The pile depths under these light towers need to be inspected to ensure current design standards are met. Inspecting the pile depth is challenging as some towers have been in place for several decades and construction records may not exist. Retrofitting or replacing light towers is costly. New MnDOT research has produced a testing method to determine pile depth without digging or dismantling. Using above-ground vibration and understanding the layers of soil in which the pile is embedded, researchers can measure seismic waves bouncing off the length of the pile. This data, combined with 3D simulations and machine learning, allows for an accurate estimation of the pile depth. This method can be executed for one-eighth of the cost of retrofitting or replacing a tower. Armed with this knowledge, MnDOT can cost-effectively prioritize which high-mast light towers need attention.

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