PacTrans-Investigation of High-Mast Light Pole Anchor Bolts

Abstract and project information last updated: 3 January 2013. Project updates are dated below.

AUTC
Project
Number
S16920
Principal
Investigator
Scott Hamel, P.E., Ph.D, Jeffrey Hoffman, P.E., Ph.D
Funding
Agency

PacTrans

AKDOT

Project
Budget
120000
Start
Date
1 June 2012
Estimated
End Date
31 October 2013

Abstract

The Alaska Department of Transportation (AKDOT) owns and maintains over onehundred
high-mast light poles that are up to 170 feet tall. These poles are used to
illuminate intersections and freeways in the central and south-central regions of Alaska.
The poles, which are also used throughout the lower 48, have experienced scrutiny in the
last decade after a number of catastrophic failures across the country. Studies have been
conducted to investigate the welds near the base and baseplate thickness. The results of
these studies and associated recommendations have been implemented by AKDOT. As
part of its review of these structures, AKDOT has found widespread and continual
loosening of the anchor bolt nuts at the base of the poles. The loosening of anchor nuts
presents a great danger as it greatly reduces the fatigue resistance of the anchor bolts, a
condition that could cause significant overstress and failure of these elements. Given
their height and proximity to major roadways, collapse of these poles would likely cause
significant damage and multiple fatalities. AKDOT has combated this problem by
instituting a labor-intensive inspection program in which each pole is inspected every 4
years. Loose nuts found by inspectors are re-tightened by maintenance crews. This
program has served as a stop-gap measure, but the level of safety provided by the fouryear
interval is not known. A more permanent solution is required to ensure the safety of
the structures and reduce inspection and maintenance efforts. The following proposal
outlines the problem background, the efforts thus far to solve the problem, and the
approach of this project to determine the cause or causes of the nut loosening and
recommend procedures to eliminate the phenomenon. One of the final results of this
project will be the development of specific guidelines for remediating the problem in
current poles, and recommendations for alternative designs for future installations.

Final Report

High-Mast Light Poles Anchor Nut Loosening in Alaska
29 Oct 2014

High-Mast Light Poles Anchor Nut Loosening in Alaska
Scott Hamel, David Hoisington
HMLP-Final-Report_PacTrans.pdf

Related Project Activity

29 October 2014

High-Mast Light Poles Anchor Nut Loosening in Alaska

by billy.connor

HMLP Final Report_PacTrans