- Zisis, I; Irwin, P; Hajra, B; Chowdhury, AG; Matus, M
- Wind induced damage on span-wire traffic signals have occurred in the past, causing significant financial loses besides disruption of traffic flow. A span-wire system consists of two wires (catenary and messenger wires) connected to posts on either side, with the signals connected to these wires through hangers. One of the objectives of this study was to assess the wind loads on a 22 ft (6.7 m) span-wire system with springs fitted on either side, consisting of two 3-section and one 5-section traffic signals connected through a flexible hanger. This configuration was tested at the Wall of Wind (WOW) experimental facility at Florida International University (FIU), Miami, USA, for, wind directions varying from 0o to 180o and wind speeds ranging from 0 to 150 mph (67 m/s). Based on force-deflection relationships, the 22 ft (6.7 m) span wire system with springs represents a 72 ft (21.5 m) long span-wire system. The advantage of having a 6.7 m span wire system with springs is that it allows the testing of traffic signals for a wide range of wind angles, as compared to the 72 ft (21.5 m) long span wire system that can only be tested for 0o. Therefore, the second objective of this study was to compare results from the 22 ft (6.7 m) span wire system with springs and the 72 ft (21.5 m) long span wire system, in order to assess the correctness of the theoretical considerations. At a given wind speed, the messenger wire experienced higher tensions than the catenary wire. The root mean square (rms) of accelerations increased with increasing wind speeds. Beyond 70 mph (31.2 m/s), the traffic signals experienced an aerodynamic instability. Good comparisons of total drag and lift forces on the traffic signals were obtained from the 22 ft (6.7 m) span wire system with springs and the 72 ft (21.5 m) span wire system at 0o. The results from this study are encouraging and demonstrate the usefulness of the test rig with springs in realistically simulating long span-wire systems.
- January 1, 2017