Editing Golden Gate Bridge (section)

== Issues ==
=== Protests and stunts ===
Since the late 1970s, the Golden Gate Bridge has seen a share of protest rallies throughout its history. In some cases, participants staged public stunts to draw heightened attention to their political messages by haphazardly scaling the bridge.<ref>{{cite news |archive-url=https://web.archive.org/web/20170324154729/http://www.sfchronicle.com/thetake/article/Golden-Gate-Bridge-stunts-that-have-shocked-the-11015413.php |archive-date=March 24, 2017 |url=http://www.sfchronicle.com/thetake/article/Golden-Gate-Bridge-stunts-that-have-shocked-the-11015413.php |newspaper=San Francisco Chronicle |title=Golden Gate Bridge stunts that have shocked the city over the years |first=Bill |last=Van Niekerken |date=March 20, 2017}}</ref><ref name="sfchronicle.com">{{cite web | url=http://www.sfchronicle.com/thetake/article/Golden-Gate-Bridge-stunts-that-have-shocked-the-11015413.php | archive-url=https://web.archive.org/web/20170324154729/http://www.sfchronicle.com/thetake/article/Golden-Gate-Bridge-stunts-that-have-shocked-the-11015413.php | archive-date=March 24, 2017 | title=Golden Gate Bridge stunts that have shocked the city over the years | date=March 20, 2017 }}</ref> On November 24, 1996, actor [[Woody Harrelson]] joined a group of local environmentalists who draped a large banner above the roadway deck protesting CEO [[Charles Hurwitz]] over his aggressive [[logging]] advances. The incident snarled traffic and caused delays lasting the entire day.<ref>{{cite web | url=https://www.latimes.com/archives/la-xpm-1996-11-24-mn-2645-story.html | title=Protesters Arrested at Golden Gate Bridge | website=[[Los Angeles Times]] | date=November 24, 1996 }}</ref> As an effort to deter any more disruptive stunts, a legislation authored by State Senator [[Quentin Kopp]] and signed into law by Governor [[Pete Wilson]] in 1997, stiffened penalties for trespassing on the bridge.<ref name="sfchronicle.com" /> Nonetheless, demonstrations have continued to take place on the Golden Gate Bridge over the years, often resulting in the complete shutdown of the bridge.{{efn|Chronicled attributes:<ref>{{Cite web |last=PEARSON |first=JENNIFER PELTZ AND JAKE |date=2018-07-05 |title=Protester's climb shuts down Statue of Liberty on July 4 |url=https://www.pressdemocrat.com/article/news/protesters-climb-shuts-down-statue-of-liberty-on-july-4/ |access-date=2024-04-18 |website=Santa Rosa Press Democrat |language=en-US}}</ref><ref>{{Cite web |title=The Militant - July 23, 2001 &ndash; San Francisco protesters demand, 'U.S. Navy Out of Vieques Now!' |url=https://www.themilitant.com/2001/6528/652862.html |access-date=2024-04-18 |website=www.themilitant.com}}</ref><ref>{{Cite web |last=ABC7 |title=Olympic torch protesters scale Golden Gate Bridge {{!}} ABC7 San Francisco {{!}} abc7news.com |url=https://abc7news.com/archive/6066082/ |access-date=2024-04-18 |website=ABC7 San Francisco |language=en}}</ref><ref>{{Cite web |title=Tibet protesters scale Golden Gate bridge - CNN.com |url=https://www.cnn.com/2008/US/04/07/bridge.protest/index.html |access-date=2024-04-18 |website=www.cnn.com}}</ref><ref>{{cite web | url=https://abc7news.com/golden-gate-bridge-human-chain-holding-hands-across-protest/1713263/ | archive-url=https://web.archive.org/web/20230525040556/https://abc7news.com/golden-gate-bridge-human-chain-holding-hands-across-protest/1713263/ | archive-date=May 25, 2023 | title=PHOTOS: Thousands gather to hold hands across Golden Gate Bridge }}</ref><ref>{{Cite web |date=2020-10-14 |title=Thousands March Across Golden Gate Bridge in Support of Artsakh |url=https://armenianweekly.com/2020/10/14/thousands-march-across-golden-gate-bridge-in-support-of-artsakh/ |access-date=2024-04-18 |website=The Armenian Weekly |language=en-US}}</ref><ref name="staff • •">{{Cite web |last=staff • • |first=NBC Bay Area |date=2023-09-11 |title=Bay Area's Armenian community rally in San Francisco |url=https://www.nbcbayarea.com/news/local/armenian-community-rally-san-francisco/3314542/ |access-date=2024-04-18 |website=NBC Bay Area |language=en-US}}</ref><ref>{{Cite web |date=2021-06-15 |title=Young climate activists marched 266 miles from Paradise to SF demanding change |url=https://abc7news.com/civilian-climate-corps-act-activists-golden-gate-bridge-march/10790176/ |access-date=2024-04-18 |website=ABC7 San Francisco |language=en}}</ref><ref>{{Cite web |last=Fernando |first=Christine |title='This injustice must stop': Protesters block Golden Gate Bridge, demand immigration reform |url=https://www.usatoday.com/story/news/nation/2021/09/30/golden-gate-bridge-blocked-protest-immigration-reform/5930606001/ |access-date=2024-04-18 |website=USA TODAY |language=en-US}}</ref><ref>{{Cite news |last=Kopan |first=Deepa Fernandes and Tal |title=Golden Gate Bridge shutdown could signal the start of more direct activism on immigration reform |url=https://www.sfchronicle.com/sf/article/Protesters-shut-down-Golden-Gate-Bridge-calling-16499023.php |access-date=2024-04-18 |work=San Francisco Chronicle |language=en}}</ref><ref>{{Cite news |last=Morris |first=By J.D. |title=Young climate activists head to the Golden Gate Bridge on 266-mile march from Paradise |url=https://www.sfchronicle.com/local/article/Youth-climate-activists-head-to-the-Golden-Gate-16245244.php |access-date=2024-04-18 |work=San Francisco Chronicle |language=en}}</ref><ref>{{Cite news |last=Flores |first=Dominic Fracassa, David Hernandez, Jessica |title=Golden Gate Bridge briefly blocked by pro-Palestinian protesters |url=https://www.sfchronicle.com/sf/article/golden-gate-bridge-gaza-protest-18667219.php |access-date=2024-04-18 |work=San Francisco Chronicle |language=en}}</ref><ref>{{Cite web |date=2024-04-15 |title=38 Pro-Palestinian protesters arrested after shutdown of Golden Gate Bridge, I-880 in Oakland: CHP |url=https://abc7news.com/pro-palestinian-protesters-shut-down-golden-gate-bridge-and-i-880-in-oakland/14668534/ |access-date=2024-04-17 |website=ABC7 San Francisco |language=en}}</ref><ref>{{Cite web |date=2024-04-16 |title=Gaza war protesters shut down Golden Gate Bridge, block traffic in other cities |url=https://www.nbcnews.com/news/us-news/gaza-war-protesters-shut-golden-gate-bridge-block-traffic-rcna147945 |access-date=2024-04-17 |website=NBC News |language=en}}</ref><ref>{{Cite web |last=Elassar |first=Alaa |date=2022-09-24 |title=Iranian Americans are demonstrating across the US in support of protesters in Iran |url=https://www.cnn.com/2022/09/24/us/iranian-american-protest-us-mahsa-amini/index.html |access-date=2024-04-18 |website=CNN |language=en}}</ref><ref>{{Cite web |date=2022-09-26 |title=Demonstrators form human chain on Golden Gate Bridge, demand justice for death of Mahsa Amini |url=https://abc7news.com/mahsa-amini-san-francisco-bay-area-protest-iranian-woman-death/12266262/ |access-date=2024-04-18 |website=ABC7 San Francisco |language=en}}</ref>}} Notably, on June 6, 2020, protestors occupied the bridge as part of a [[George Floyd protests|nationwide denunciation]] to [[police brutality]] in the wake of the [[murder of George Floyd|George Floyd's murder]],<ref>{{cite news |title='Lead with Love': Meet the 2 Bay Area teens who organized, led massive Black Lives Matter rally on Golden Gate Bridge |url=https://abc7news.com/black-lives-matter-george-floyd-peaceful-protest-sf-police/6238147/ |access-date=2 April 2024 |agency=KABC-TV}}</ref><ref>{{cite news |last1=Bellow |first1=Noelle |title=Golden Gate Bridge protest was organized by teens seeking change |url=https://www.kron4.com/news/bay-area/golden-gate-bridge-protest-was-organized-by-teens-seeking-change/ |access-date=2 April 2024 |agency=KRON-TV |date=2020 |archive-date=March 22, 2024 |archive-url=https://web.archive.org/web/20240322000325/https://www.kron4.com/news/bay-area/golden-gate-bridge-protest-was-organized-by-teens-seeking-change/ |url-status=dead }}</ref><ref>{{Cite web |last=Grindell |first=Samantha |title=Thousands of protesters marched across San Francisco's Golden Gate Bridge, temporarily shutting it down to traffic |url=https://www.businessinsider.com/san-francisco-golden-gate-bridge-george-floyd-protest-2020-6 |access-date=2024-04-18 |website=Business Insider |language=en-US}}</ref> and in November 2021 two [[California Highway Patrol]] officers and three bridge employees were injured in a vehicular chain-reaction crash during a protest against [[COVID-19 vaccination mandates in the United States|government-mandated COVID-19 vaccinations]].<ref>{{Cite web |date=2021-11-12 |title=5 hurt, including 2 officers, after crash at anti-vaccine protest in San Francisco |url=https://www.nbcnews.com/news/us-news/5-hurt-2-officers-crash-anti-vaccine-protest-san-francisco-rcna5382 |access-date=2024-04-18 |website=NBC News |language=en}}</ref><ref>{{Cite web |date=2021-11-11 |title=5 People Hit, CHP Officer Hospitalized in Crash on Golden Gate Bridge During Anti-Vax Protest - CBS San Francisco |url=https://www.cbsnews.com/sanfrancisco/news/anti-vax-vaccine-mandate-golden-gate-bridge-san-francisco/ |access-date=2024-04-18 |website=www.cbsnews.com |language=en-US}}</ref> In February 2024 and again in April, pro-Palestinian protestors gathered on the deck to decry the [[Gaza war]] and the [[Israeli invasion of the Gaza Strip (2023–present)|turmoil afflicting Palestinians]] in [[Gaza Strip|Gaza]].<ref>{{cite web | url=https://www.cbsnews.com/sanfrancisco/news/second-protest-blocks-all-lanes-of-golden-gate-bridge-san-francisco/ | title=Gaza protest shuts down Golden Gate Bridge, causing gridlock on both sides of span - CBS San Francisco | website=[[CBS News]] | date=April 15, 2024 }}</ref><ref>{{cite web |date=February 14, 2024 |title=Pro-Palestinian protesters block traffic on Golden Gate Bridge in San Francisco - CBS San Francisco |url=https://www.cbsnews.com/sanfrancisco/news/golden-gate-bridge-protest-traffic-san-francisco/ |website=[[CBS News]]}}</ref>

===Suicides===
{{Main|Suicides at the Golden Gate Bridge}}
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The Golden Gate Bridge was the most used [[List of suicide sites|suicide site]] in the world prior to the installation of suicide prevention nets.<ref>{{cite news |first=James |last=Bone |title=Golden Gate bridge in San {{sic|Fransico |nolink=y}} gets safety net to deter suicides|newspaper=The Times |url=http://journalisted.com/article/jdey |via=Journalisted |archive-url=https://web.archive.org/web/20170525091537/http://journalisted.com/article/jdey |archive-date=May 25, 2017 |date=October 13, 2008}}</ref> Jumpers would fall for four seconds,<ref name=":1">{{cite news |last=Branch |first=John |date=November 5, 2023 |title=What the Golden Gate Is (Finally) Doing About Suicides |work=[[The New York Times]] |url=https://www.nytimes.com/2023/11/05/us/golden-gate-bridge-suicide-nets.html}}</ref> then hit the water at around {{cvt|75|mph|km/h m/s|-1||}}. Most would die from impact [[Trauma (medicine)|trauma]].<ref name=":1" /> About 5% would survive the initial impact but generally [[drown]] or die of [[hypothermia]] in the cold water.<ref name="lethal4">{{cite news |title=Lethal Beauty. No easy death: Suicide by bridge is gruesome, and death is almost certain. The fourth in a seven-part series on the Golden Gate Bridge barrier debate. |first1=John |last1=Koopman |date=November 2, 2005 |url=http://www.sfgate.com/news/article/LETHAL-BEAUTY-No-easy-death-Suicide-by-bridge-2562269.php#page-1 |newspaper=[[San Francisco Chronicle]] |access-date=June 3, 2014}}</ref><ref name="LAtimess">{{cite web |last=Bateson |first=John |url=https://www.latimes.com/archives/la-xpm-2013-sep-29-la-oe-bateson-golden-gate-bridge-suicides-20130929-story.html |archive-url=https://web.archive.org/web/20131009064346/http://articles.latimes.com/2013/sep/29/opinion/la-oe-bateson-golden-gate-bridge-suicides-20130929 |url-status=live |archive-date=October 9, 2013 |title=The suicide magnet that is the Golden Gate Bridge |newspaper=Los Angeles Times |date=September 29, 2013 |access-date=October 14, 2013 |type=opinion}}</ref> After years of debate and an estimated more 2,000 deaths, implementation of suicide prevention barriers began in April 2017.<ref>{{cite news |first=Will |last=Houston |url=https://www.ukiahdailyjournal.com/2019/02/18/golden-gate-bridge-suicide-barrier-starting-to-take-shape/ |title=Golden Gate Bridge suicide barrier starting to take shape |newspaper=[[Ukiah Daily Journal]] |date=February 18, 2019}}</ref><ref name=":1" />

[[File:Suicide nets on the Pacific side of the Golden Gate Bridge.jpg|thumb|Suicide nets on the Pacific side of the Golden Gate Bridge in December 2022]]

==== Suicide nets ====
The so-called nets are taut, designed to be painful to land on. They extend {{convert|20|ft}} out from the walkway and because of their design, cause serious—but not fatal—injury to people who jump from the bridge.<ref name=":1" /><ref>{{Cite web |title=How The Net Works {{!}} Golden Gate |url=https://www.goldengate.org/district/district-projects/suicide-deterrent-net/how-the-net-works/ |access-date=2025-03-02 |website=www.goldengate.org}}</ref> They are made of "marine-grade stainless-steel wire rope, akin to a horizontal fence four millimeters thick," which does not give, and is located {{convert|20|ft}} below the walkway.<ref>{{Cite web |date=2024-08-17 |title=The Golden Gate Bridge's anti-suicide "nets" are already saving lives |url=https://sfstandard.com/2024/08/17/golden-gate-bridge-anti-suicide-nets-work/ |access-date=2025-03-02 |website=The San Francisco Standard |language=en}}</ref>

Construction was first estimated to take approximately four years at a cost of over $200 million; however, installation of the nets was not completed until January 2024, and exceeded the budget by $17 million.<ref name="abc7-3jan2024">{{cite news |last=Stone |first=J.R. |title=San Francisco installs $224M net to stop suicides off Golden Gate Bridge |url=https://abc7news.com/golden-gate-bridge-suicide-nets-kevin-hines-suicides-survivors/14268993/ |access-date=January 5, 2024 |work=[[KGO-TV]] |date=January 3, 2024}}</ref><ref>{{cite web |title=Suicide Barriers Going Up At Golden Gate Bridge After Over 1.5K Deaths |url=http://sanfrancisco.cbslocal.com/2017/04/13/suicide-barriers-to-go-up-at-golden-gate-bridge-after-1-5k-deaths/ |website=CBS San Francisco |publisher=CBS Broadcasting Inc. |access-date=November 27, 2017 |language=en |date=April 13, 2017}}</ref><ref name=":1" />

The nets have widely been considered successful, even convincing former skeptics. As of November 21, 2024, the [[Golden Gate Bridge, Highway and Transportation District|Golden Gate Bridge Highway and Transportation District]] reported that the number of deaths by suicide year to date had been eight, down from an average 33.5. Through the end of October 2024, thwarted attempts were down from an annual average of 200 to 106.<ref>{{Cite news |last=Swan |first=Rachel |title=Golden Gate Bridge suicide nets have been up for nearly a year. Are they effective? |url=https://www.sfchronicle.com/bayarea/article/golden-gate-bridge-suicide-barrier-do-they-work-19926874.php |archive-url=https://web.archive.org/web/20250222072510/https://www.sfchronicle.com/bayarea/article/golden-gate-bridge-suicide-barrier-do-they-work-19926874.php |archive-date=February 22, 2025 |access-date=2025-03-02 |work=San Francisco Chronicle |language=en |url-status=live }}</ref><ref name=":1" />

===Wind===
The Golden Gate Bridge was designed to safely withstand winds of up to {{convert|68|mph|km/h|0|abbr=on}}.<ref name=Chron-sing>{{cite news |first=Rachel |last=Swan |url=https://www.sfchronicle.com/bayarea/article/Hear-that-ghostly-hum-on-the-Golden-Gate-Bridge-15321948.php |title=Hear that ghostly hum on the Golden Gate Bridge? It's here to stay |newspaper=San Francisco Chronicle |date=June 8, 2020 }}</ref><ref>{{Cite news |last=McCormick |first=Erin |date=2021-06-13 |title=The quest to solve the mysterious 'eerie' hum of the Golden Gate Bridge |url=https://www.theguardian.com/us-news/2021/jun/13/golden-gate-bridge-hum-noise-san-francisco |access-date=2025-03-02 |work=The Guardian |language=en-GB |issn=0261-3077}}</ref> Until 2008, the bridge was closed because of weather conditions only three times: on December 1, 1951, because of gusts of {{convert|69|mph|km/h|0|abbr=on}}; on December 23, 1982, because of winds of {{convert|70|mph|km/h|0|abbr=on}}; and on December 3, 1983, because of wind gusts of {{convert|75|mph|km/h|0|abbr=on}}.<ref name="goldengatebridge facts">{{cite web |url=http://goldengatebridge.org/research/facts.php |title=Frequently Asked Questions about the Golden Gate Bridge |publisher=Golden Gate Bridge, Highway and Transportation District |access-date=March 12, 2008 |archive-date=August 10, 2015 |archive-url=https://web.archive.org/web/20150810050111/http://goldengatebridge.org/research/facts.php |url-status=dead }}</ref> An [[anemometer]] placed midway between the two towers on the west side of the bridge has been used to measure wind speeds and direction. Another anemometer was placed on one of the towers.<ref>{{cite web | url=https://www.iitk.ac.in/nicee/wcee/article/8_vol6_63.pdf | title=Full-Scale Ambient Vibration of the Golden Gate Suspension Bridge—Intrumentation and Data Acquisition | accessdate=17 February 2025 | author=Nigbor, R.L.}}</ref>

==== Wind safety retrofit introduces wind "songs" ====
[[File:Bridge Whistle.wav|thumb|A recording of the noise produced by the Golden Gate Bridge taken in the Presidio of San Francisco on Sunday March 2, 2025.]]
In June 2020 residents across [[San Francisco County|San Francisco]] and [[Marin County, California|Marin]] Counties began to notice a humming noise. The noise has been described as "eerie", "a shrill screeching sound", and for some evokes a feeling that "something bad is about to happen."<ref>{{Cite news |last=Bartlett |first=Amanda |title=SF officials say an end is coming to the Golden Gate Bridge's eerie song |url=https://www.sfgate.com/local/article/golden-gate-bridge-song-san-francisco-19952341.php |archive-url=https://web.archive.org/web/20241208020646/https://www.sfgate.com/local/article/golden-gate-bridge-song-san-francisco-19952341.php |archive-date=December 8, 2024 |access-date=2025-03-02 |work=SFGATE |language=en |url-status=live }}</ref><ref>{{Cite news |last=Swan |first=Rachel |title=San Francisco Golden Gate Bridge's infamous 'singing' will finally go away |url=https://www.sfchronicle.com/sf/article/golden-gate-bridge-singing-noise-fix-19934862.php |archive-url=https://web.archive.org/web/20250222072456/https://www.sfchronicle.com/sf/article/golden-gate-bridge-singing-noise-fix-19934862.php |archive-date=February 22, 2025 |access-date=2025-03-02 |work=San Francisco Chronicle |language=en |url-status=live }}</ref><ref name=":2">{{Cite web |date=2023-01-12 |title=Why the Golden Gate Bridge Sounds Like It's Screaming Bloody Murder Right Now |url=https://www.popularmechanics.com/science/a42476120/why-golden-gate-bridge-is-screaming/ |access-date=2025-03-02 |website=Popular Mechanics |language=en-US}}</ref> The [[Golden Gate Bridge, Highway and Transportation District|Golden Gate Bridge Highway and Transportation District]] determined that the "unsettling" whistle is produced by new railing slats when a strong [[West wind|zephyr]] blows.<ref name="bridge harmonic resonance issues">{{cite news |first=Eric |last=Ting |url=https://www.sfgate.com/bayarea/article/Golden-Gate-Bridge-noise-humming-why-wind-sound-15321767.php |title=Why the Golden Gate Bridge made strange noises with the wind Friday |newspaper=San Francisco Chronicle |date=June 6, 2020 |access-date=June 6, 2020 |archive-date=July 5, 2020 |archive-url=https://web.archive.org/web/20200705073455/https://www.sfgate.com/bayarea/article/Golden-Gate-Bridge-noise-humming-why-wind-sound-15321767.php }}</ref>

The new slats were installed starting in 2019 on the west side of the bridge; they are more flexible than their predecessors and were selected to improve the bridge's aerodynamic tolerance of high wind to {{convert|100|mph|km/h|0|abbr=on}}. The sound had been predicted from [[wind tunnel]] tests,<ref name="Chron-sing" /> but not included in the environmental impact report.<ref>{{cite news |last=Chamings |first=Andrew |date=July 1, 2020 |title=Golden Gate Bridge officials look to fix 'screeching that sounds like torture' |url=https://www.sfgate.com/living-in-sf/article/San-Francisco-Golden-Gate-Bridge-singing-fix-15379759.php |newspaper=San Francisco Chronicle}}</ref>

The Bridge District determined that, in fact, there are two sounds that the bridge produces. When the wind passing through the slats reaches {{Convert|22|mph|km/h|abbr=on}}, "a low-pitched, low-frequency tone—between 280 and 700 [[hertz]]" is produced.<ref name=":2" /> When the wind passes through the slats at an angle and reaches {{Convert|27|mph|km/h|abbr=on}}, the slats produce "higher pitch and frequency (1.1 [[kHz]])."<ref name=":3">{{Cite web |title=Bridge Sounds During High Wind Events - Suicide Deterrent Net {{!}} Golden Gate |url=https://www.goldengate.org/district/district-projects/suicide-deterrent-net/bridge-sounds-during-high-wind-events/ |access-date=2025-03-02 |website=www.goldengate.org}}</ref>

On December 16, 2021, the Bridge District approved a fix for the noise; 12,000 '''∪'''-shaped clips with rubber dampers are to be installed between the slats at a cost of $450,000.<ref>{{Cite web |date=December 16, 2021 |title=APPROVE ACTIONS RELATIVE TO REDUCING WIND INDUCED SOUND EMANATED BY THE GOLDEN GATE SUSPENSION BRIDGE WEST RAILING |url=https://www.goldengate.org/assets/1/25/2021-1216-bocomm-no3-appractreducingwindretrofit.pdf?7522 |website=goldengate.org}}</ref> Testing suggests that this fix will reduce the noise by 75%; however, even with the fix, the bridge is expected to emit the high frequency tone an average of 70 hours per year; the low frequency tone is expected 18 hours per year. The Bridge District expects instillation to be "completed in 2025."<ref name=":3" />

An independent engineering analysis of a 2020 sound recording of the tones concludes that the singing noise comprises a variety of [[Physics of whistles#Aeolian tone|Aeolian tone]]s (the sound produced by air flowing past a sharp edge), arising in this case from the ambient wind blowing across metal slats of the newly installed sidewalk railings.<ref>{{cite web|url=https://vibrationdata.wordpress.com/2020/07/13/golden-gate-bridge-singing/|title=Golden Gate Bridge Singing|website=Vibrationdata: Shock & Vibration Software & Tutorials|author=Tom Irvine|date=July 13, 2020|access-date=December 1, 2021}}</ref> The tones observed were frequencies of 354, 398, 439 and 481&nbsp;Hz, corresponding to the [[musical note]]s F<sub>4</sub>, G<sub>4</sub>, A<sub>4</sub>, and B<sub>4</sub>; these notes form an F Lydian Tetrachord.

===Seismic vulnerability and improvements{{Anchor|Seismic retrofit}}===
[[File:Details Golden Gate Bridge 04 2015 SFO 1951.jpg|thumb|South approach sub-structure with [[Seismic base isolation|seismic isolators]] (short black cylinders) added as part of the Seismic Retrofit Construction Project]]
Modern knowledge of the effect of earthquakes on structures led to a program to [[Seismic retrofit|retrofit]] the Golden Gate to better resist seismic events. The proximity of the bridge to the [[San Andreas Fault]] places it at risk for a significant earthquake. Once thought to have been able to withstand any magnitude of foreseeable earthquake, the bridge was actually vulnerable to complete structural failure (i.e., collapse) triggered by the failure of supports on the {{convert|320|ft|m|adj=on}} arch over Fort Point.<ref>{{cite news |title=70 Years: Spanning the Golden Gate: New will blend in with the old as part of bridge earthquake retrofit project |first=Carl |last=Nolte |author-link=Carl Nolte |newspaper=San Francisco Chronicle |date=May 28, 2007 |url=https://www.sfgate.com/bayarea/article/70-YEARS-Spanning-the-Golden-Gate-New-will-2558505.php }}</ref> A $392&nbsp;million program was initiated to improve the structure's ability to withstand such an event with only minimal (repairable) damage. A custom-built electro-hydraulic synchronous lift system for construction of temporary support towers and a series of intricate lifts, transferring the loads from the existing bridge onto the temporary supports, were completed with engineers from [[Balfour Beatty]] and [[Enerpac]], without disrupting day-to-day commuter traffic.<ref>[http://www.roadsbridges.com/showing-fancy-foot-work Showing fancy foot work] {{Webarchive|url=https://web.archive.org/web/20210123132652/http://www.roadsbridges.com/showing-fancy-foot-work |date=January 23, 2021 }}. ''Roads&Bridges'' (December 28, 2000).</ref><ref name = "retrofit">{{cite web |url=http://goldengatebridge.org/projects/retrofit.php |title=Overview of Golden Gate Bridge Seismic Retrofit |access-date=June 21, 2008 |author=Golden Gate Bridge Authority |date=May 2008 |archive-date=June 16, 2008 |archive-url=https://web.archive.org/web/20080616091141/http://goldengatebridge.org/projects/retrofit.php |url-status=dead }}</ref> Although the retrofit was initially planned to be completed in 2012, {{As of|2017|05|lc=y}} it was expected to take several more years.<ref name = "retrofit"/><ref>{{cite web |url=http://enr.construction.com/features/transportation/archives/050103-1.asp |title=Famed Golden Gate Span Undergoes Complex Seismic Revamp |access-date=June 21, 2008 |last=Gonchar |first=Joann |date=January 3, 2005 |publisher=McGraw-Hill Construction}}</ref><ref>{{Cite web|url=https://sanfrancisco.cbslocal.com/2017/05/24/costly-golden-gate-bridge-retrofit-still-years-away-from-completion/|title=Costly Golden Gate Bridge Retrofit Still Years Away From Completion|date=May 24, 2017|access-date=July 29, 2019}}</ref>

{{Anchor|Doyle Drive replacement project}}
The former elevated approach to the Golden Gate Bridge through the [[Presidio of San Francisco|San Francisco Presidio]], known as Doyle Drive, dated to 1933 and was named after Frank P. Doyle, a director of the [[California State Automobile Association]].<ref>{{cite book |url=http://www.presidioparkway.org/about/history.aspx |title=Presidio Parkway re-envisioning Doyle Drive |publisher=Presidio Parkway Project |access-date=May 6, 2010 |archive-date=December 26, 2009 |archive-url=https://web.archive.org/web/20091226180130/http://www.presidioparkway.org/about/history.aspx }}</ref> The highway carried about 91,000 vehicles each weekday between downtown San Francisco and the [[North Bay (San Francisco Bay Area)|North Bay]] and points north.<ref>{{cite web |url=http://www.sfcta.org/content/view/275/94/ |title=Doyle Drive Replacement Project |publisher=San Francisco County Transportation Authority |access-date=May 6, 2010 |archive-url=https://web.archive.org/web/20100426064515/http://www.sfcta.org/content/view/275/94/ |archive-date=April 26, 2010 }}</ref> The road was deemed "vulnerable to earthquake damage", had a problematic 4-lane design, and lacked shoulders; a San Francisco County Transportation Authority study recommended that it be replaced. Construction on the $1&nbsp;billion replacement,<ref>{{cite web |url=https://www.sfgate.com/bayarea/article/Doyle-Drive-makeover-will-affect-drivers-soon-3276621.php |archive-url=https://web.archive.org/web/20100316012125/http://articles.sfgate.com/2010-01-05/bay-area/17466642_1_doyle-drive-caltrans-closures |url-status=live |archive-date=March 16, 2010 |title=Doyle Drive makeover will affect drivers soon |last=Cabanatuan |first=Michael |date=January 5, 2010 |newspaper=San Francisco Chronicle |access-date=May 6, 2010}}</ref> temporarily known as the Presidio Parkway, began in December 2009.<ref>{{cite book |url=http://www.presidioparkway.org/construction_info/ |title=Current Construction Activity |series=Presidio Parkway re-envisioning Doyle Drive |publisher=Presidio Parkway |access-date=May 6, 2010 |archive-date=April 26, 2010 |archive-url=https://web.archive.org/web/20100426112839/http://www.presidioparkway.org/construction%5Finfo/ }}</ref>
The elevated Doyle Drive was demolished on the weekend of April 27–30, 2012, and traffic used a part of the partially completed Presidio Parkway, until it was switched onto the finished Presidio Parkway on the weekend of July 9–12, 2015. {{as of|2012|May|}}, an official at Caltrans said there is no plan to permanently rename the portion known as Doyle Drive.<ref>{{cite news |url=http://www.pressdemocrat.com/article/20120501/news/205011005?tc=ar |title=Smith: It's wrecked, but it's still 'Doyle Drive' |newspaper=Press Democrat |date=May 1, 2012 |access-date=May 2, 2012 |archive-date=March 13, 2014 |archive-url=https://web.archive.org/web/20140313152842/http://www.pressdemocrat.com/article/20120501/news/205011005?tc=ar }}</ref>
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