Texas Tech University

Project 0-4586

Revision of AASHTO Fatigue Design Loadings for Signs, Luminaires, and Traffic Signals, for Use in Texas

Abstract

The wind-induced vibrations of the mast arm of cantilever traffic signal structures can lead to the fatigue failure of these structures. For this project, both full-scale and wind tunnel tests were conducted to study the behavior of the structures. Results of these experiments indicated that when the signals have backplates, vortex shedding can cause large-amplitude vibrations that may lead to fatigue failure. These results contradict what has been generally accepted by other researchers: that galloping is the main cause for the fatigue inducing vibrations and that vortex shedding is of no relevance in this type of structure. As a result of this research, a methodology to estimate the fatigue life of these structures was developed. Using the climatology of the region, the methodology was applied as a risk assessment model to traffic signal structures of the city of Lubbock. Guidance is given on how life-cycle cost analysis can be applied to the structures.

Project PI: Chris W. Letchford


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cantilever traffic signals