Editing Golden Gate Bridge (section)

== Navigational aid ==
===Beacons===
[[File:Golden Gate Bridge by night.jpg|alt=Golden Gate Bridge by night.|thumb|255x255px|[[Long-exposure photography|Time-exposed]] image of the Golden Gate Bridge illuminated on a clear night, complemented by its aerial and maritime beacons.]]
The Golden Gate Bridge's first [[aircraft warning lights]] used rotating [[aerobeacon]]s at the top of the towers that flashed red. In the 1980s, the present-day 750-watt red lamps were put into service, along with 16 red outline lanterns on the cables to enhance the structure's visibility at night.<ref name="foghorns and beacons">{{cite web |url=https://www.goldengate.org/bridge/history-research/bridge-features/foghorns-beacons/ | title= Foghorns & Beacons |author=Golden Gate Bridge Authority |access-date=14 February 2025}}</ref> For maritime movement, the bridge has white and green [[Sea mark|navigation lights]] on both sides at the midspan and red safety lights marking the south tower's fender.<ref>{{cite web | url=https://radianthistory.com/lighting-the-golden-gate-bridge-scale-and-dignity/ | title=Lighting the Golden Gate Bridge: Scale and Dignity | work=Radiant History | date=March 18, 2024 | accessdate=14 February 2025}}</ref><ref name="safety">{{cite web | url=https://info.cecr.in/the-golden-gate-bridge/ | title=The Golden Gate Bridge: The Most Photographed Bridge in the World | work=Civil Engineering and Construction Review | accessdate=14 February 2025 | author=Batra, Amrita}}</ref>

===Foghorns{{Anchor|Golden Gate Bridge Foghorns}}===
{{See also|San Francisco fog}}
Commonly, particularly during the summer months, fog on the strait becomes so dense that it can fully obscure the whole bridge,<ref>{{cite web | url=https://www.sfgate.com/entertainment/article/When-the-foghorns-blow-3292917.php | title=When the foghorns blow | publisher=SFGate | date=6 July 2009 | accessdate=15 February 2025 | author=Whiting, Sam}}</ref> creating an even greater hazard for mariners.<ref name="safety" /> A system of five [[foghorns]] was thus set up on the bridge in 1937 and remains operational to this day. The fog signals are [[air horn|air-powered]] and are manually switched on and off.<ref>{{cite web | url=https://www.kqed.org/news/11272504/foghorns-who-presses-the-play-button | title=Foghorns: Who Presses The Play Button? | publisher=KQED | date=19 January 2017 | accessdate=14 February 2025 | author=Klivans, Laura}}</ref><ref name="foghorn control">{{cite web | url=https://thesanfranciscanmagazine.com/lifesaving-signals/ | title=Lifesaving Signals | publisher=The San Franciscan | accessdate=14 February 2025 | author=Mitchell, James}}</ref><ref name="Forged in the Fog">{{cite AV media | url=https://www.youtube.com/watch?v=IdnDQwbjkMA | title=The Golden Gate Bridge Presents: Forged in the Fog / E03 / Phil Farrelly | publisher=Golden Gate Bridge District | date=February 7, 2010 | medium=Video | location=YouTube |access-date=14 February 2025}}</ref> [[United States Coast Guard|Coast Guard]] regulates the pattern and pitch by which the horns must sound.<ref name="foghorns and beacons" />

Two foghorns are mounted at the base of the south tower {{convert|40|ft|m}} above water level (at high tide).<ref name="foghorn control"/> They each point in the opposite direction, west and east, and have an identical profile: {{convert|48|in|cm}} long and a {{convert|23+1/2|in|cm|adj=on}} diameter [[Bell (wind instrument)|bell]]. Both horns sound in tandem, producing a 2-second blast every 18 seconds<ref name="foghorns and beacons" /> in a distinctively low tone.<ref name="when it's foggy">{{cite web |url=https://www.goldengate.org/exhibits/when-its-foggy-foghorns/ | title= When It's Foggy |author=Golden Gate Bridge Authority |access-date=14 February 2025}}</ref><ref>{{cite web | url=https://www.thrillist.com/entertainment/san-francisco/golden-gate-bridge-history-sf-facts | title=13 things you didn't know about the Golden Gate Bridge | publisher=Thrillist | date=17 November 2014 | accessdate=14 February 2025 | author=Barringer, Daisy}}</ref> On October 18, 2013, at around 2:00{{nbsp}}a.m., one foghorn sounded perpetually for nearly an hour due to a malfunctioning relay. It was disconnected by 3:00{{nbsp}}a.m. and repaired later that morning.<ref>{{cite news | url=https://patch.com/california/sanrafael/did-you-hear-that-foghorn_951cbc3b | title=Did You Hear That Foghorn? | work=Patch | date=18 October 2013 | accessdate=14 February 2025 | author=Hulac, Kari}}</ref>

The other three foghorns are mounted at the midspan of the bridge, just beneath the deck.<ref>{{cite web | url=https://www.mercurynews.com/2018/01/21/insiders-guide-you-think-you-know-the-golden-gate-bridge/ | title=Insider's Guide: You think you know the Golden Gate Bridge? | publisher=Mercury News | date=22 January 2018 | accessdate=14 February 2025 | author=Hill, Angela}}</ref> Two westward-facing horns are each {{convert|36|in|cm}} long with an {{convert|18|in|cm|adj=on}} diameter bell and emit a higher tone than the horns on the south tower.<ref name="foghorns and beacons" /> The third horn facing east is smaller, with a length of {{convert|24+1/2|in|cm}} and a bell diameter of {{convert|11|in|cm}}, thus emitting an even higher note.<ref name="when it's foggy" /> Altogether, the three horns produce two 1-second blasts every 36 seconds with a dual-toned timbre;<ref name="foghorns and beacons" /> they are synchronized to sound after every two blasts of the south tower horns.<ref>{{cite AV media | url=https://www.youtube.com/watch?v=KjM_qD14mpI | title=Foghorns on the Golden Gate Bridge Natural Sound 45mins | publisher=Thomas Pikolin | date=May 23, 2020 | medium=Video | location=YouTube}}</ref> Ships heading in either direction generally stay to the right of the midspan by following the sound of these horns. Dating back to 1985, the midspan foghorns replaced the original horns that had partly failed in the late 1970s, causing them to sound with only a single tone.<ref name="foghorns and beacons" />

The foghorns blared wildly as ''[[Queen Mary 2]]'' passed under the bridge for her 2007 visit in San Francisco.<ref>{{cite AV media | url=https://www.youtube.com/watch?v=NLBPaR8YTes | title=Queen Mary 2 Under the Golden Gate | date=9 November 2007 | medium=Video | location=YouTube}}</ref><ref>{{cite AV media | url=https://www.youtube.com/watch?v=H7Xz5R5BGjA | title=Queen Mary 2 leaving San Francisco | date=6 February 2007 | medium=Video | location=YouTube}}</ref>