A gentle breeze can make a traffic signal fall onto somebody's head. Especially those really big stop lights along America's wide roads. I talk with three traffic signal experts who work to keep traffic signals safe.
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Factual sources:
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"Reducing Fatigue in Wind-Excited Traffic Signal Support
Structures using Smart Damping Technologies," Richard Christenson, University of Connecticut, Jan 2011. https://onlinepubs.trb.org/onlinepubs/idea/finalreports/highway/nchrp141_final_report.pdf
Interview with Carl Macchietto, Valmont Structures, 29 Nov 2022.
Interview with Mark Taylor and Adam Lough, Utah Department of Transportation, 17 Apr 2023.
"Fatigue Design Categories For Pole Structures," Design Memorandum, Washington State Department of Transportation, 19 Apr 2011.
https://www.wsdot.wa.gov/eesc/bridge/designmemos/01-2011.pdf
"State Route 160: Multi-Year Expansion Program," PowerPoint presentation to the Nevada State Legislature, 10 Feb 2006.
https://www.leg.state.nv.us/App/InterimCommittee/REL/Document/23049?rewrote=1
"Staker awarded long-awaited SR-36 project," Karen Lee Scott and Troy Boman, Tooele Transcript Bulletin, 27 May 2004.
"Erda sign raises SR-36 worries," Karen Lee Scott and Troy Boman, Tooele Transcript Bulletin, 2 Sept 2004.
"Attentive driving key as SR-36 work proceeds," Karen Lee Scott and Troy Boman, Tooele Transcript Bulletin, 30 Sept 2004.
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Galloping videos (with permission):
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"Wind has the traffic light bouncing," @zj_rides117
https://www.youtube.com/shorts/hz1g18v2Zv8
"Wind shaking traffic light heavily," @52_Pickup
https://www.youtube.com/shorts/AjKmhcMbyyE
"Stop Light Blown Down By Strong Chicago Winds," @devodare_chicago7748
https://www.youtube.com/shorts/R6VX0x4A6D8
"Strong Wind Shaking Traffic Light Pole," Samroon Vlog
https://www.youtube.com/watch?v=ABIfddE0zUs
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Time sections:
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Stop lights can fall down (0:00)
Trouble in Tooele (0:40)
Galloping fatigue (3:16)
Nevada's fat paperclip (5:50)
Vortex shedding (7:45)
Reduce galloping (9:12)
Harmonic resonance (12:01)
Valmont Mitigator TR1 (15:12)
Not an ad (17:48)