Parametric Study to Investigate Span-wire Traffic Signal System Performance during Tropical Storms

Benito Alejandro Berlanga Ioannis Zisis ^* Manuel Matus Ziad Azzi Peter Irwin

• Florida International University, Miami, United States

In Florida, many highway intersections use span-wire systems to support traffic signals, making their ability to withstand extreme wind events, like hurricanes, crucial for safety. These systems' responses can be significantly influenced by installation parameters such as wire sag and tension, which vary across intersections. The goal of this research was to better understand how these factors impact the system's wind response. To achieve this, an experimental program was developed to measure the effects of catenary cable sag, messenger cable pretension, and the location of cable end supports using load cells, accelerometers, and inclinometers; data that was then used to calibrate numerical models to assess the system’s response with more refined setup parameter modifications. Experimental results showed a strong correlation between installation parameters and the system's performance under wind loading. For instance, increasing the value of catenary sag (from 5% to 7%) reduced drag forces and the root mean square (RMS) of accelerations, making the system with a more advantageous aerodynamic response to wind forces. Numerical models for long and short spans were developed to quantify and evaluate the span-wire assemblies, comparing them with full-scale experimental results obtained experimentally. These models helped to assess forces, inclinations, and wire deflections developed by span-wire systems. A theoretical buffeting analysis was conducted to evaluate the signal assembly's response to fluctuating wind speeds, providing RMS, mean, and peak values for acceleration and deflection in the wind direction. These results were compared to full-scale experimental data, providing a good agreement between experimental results, and numerically obtained estimations.