Using Helical Strakes on Pole Structures to Reduce Vibration from High-speed Winds

Metal pole structures are often used to support street lights and traffic lights and the primary force that they are subjected to is wind. The poles are susceptible to failure due to high-speed winds, but perhaps more seriously due to fatigue as a result of repetitive bending and torsion due to buffeting and vortex shedding. There have been accidents, some fatal, due to failing poles. Helical strakes have been used to support vertical structures (e.g. chimneys or outdoor piping) in the wind. In this project, the use of helical strakes on traffic light poles was investigated. First of all a detailed literature review of the topic was conducted. Next, a database of cases of failures as reported in the media was built. The relevant codes and design guidelines, particularly for Minnesota, were reviewed. Lab experiments were conducted using actual traffic light poles. Accelerations, wind speed, and pressure were measured both with and without helical strakes. The results indicate that helical strakes may be effective at reducing the vibrations of the traffic light poles. Because of the vulnerability of traffic lights to wind, implementing this technology on modern traffic lights might be an excellent solution to help them resist the effects of high-speed winds and become less expensive to maintain over time