The Golden Gate Bridge that connects San Francisco, California, with Marin County to the north was built from 1933 to 1937. Once upon a time it was the longest suspension bridge in the world at 1.7 miles. It remains a major transportation segment for the San Francisco Bay Area drawing millions of commuters and tourists each year. It was considered by the American Society of Civil Engineers to be one of the Wonders of the Modern World. However, there are some interesting little-known facts about the span, not the least of which is the day that it actually flattened out by about seven feet.
How a Suspension Bridge Works: A suspension bridge by design consists of two strong cables that run across two or more uprights in the middle of the body of water being crossed. From the suspension cables that connect the uprights with the land on each end of the bridge, a large group of cables are extended down to hold the surface of the bridge. Picture a clothesline running across two rakes several feet apart with the handles placed down in the dirt. The clothesline is secured on both ends. Coat hangers are hanging on the clothes line and a long plank of wood runs through the coat hangers. This oversimplification may help to picture how the suspension bridge holds up its road surface.
Hazards Encountered: An earthquake in 1935 during the construction phase shook the bridge site causing the two uprights that had been nearly built to sway as much as sixteen feet in either direction. A safety net during construction was added under the bridge’s width that saved the lives of nineteen workmen who fell off the bridge. Even that and other safety measures did not save eleven workmen who died during construction. In December, 1951, a windstorm revealed that the bridge span could sway, and had rolling instabilities. Bracing was added to stiffen the bridge deck in torsion. Over time, sea salt from the marine air caused corrosion in the rebar that supported the concrete road surface enabling the concrete to crumble and separate. From 1982 to 1986, the concrete road surface was replaced segment by segment with orthotropic structural steel without closing the entire bridge. The bridge was painted first with a red-orange primer, amid lobbying by the Navy for colors that would be more visible during foggy days. The primer was never covered with paint of a different color, but it had to be replaced as it was lead-based. Over a thirty-year period ending in 1995, the old primer was removed and replaced by a zinc-based primer which was more environmentally friendly.
Suicides: The Golden Gate Bridge has the distinction of being the world’s most popular suicide site. An estimated 1,500 people have jumped from the span to end their lives. The road surface is about 245 feet from the water. A jumper’s fall takes about four seconds to impact and reaches a speed of about seventy-five miles per hour. Most die from the trauma stemming from the impact, however, about five percent survived only to die of hyperthermia or drown. In an effort to stem the suicides, a project to extend stainless steel netting off to the side of the bridge was started. Other suicide prevention measures include special telephones and text lines directly to crisis hot lines.
Opening Day Was for Pedestrians Only: The Day the Bridge opened, on May 27, 1937, an estimated 200,000 people crossed the bridge. A number of “firsts” were established such as the first to run across, first to roller skate, first to push a baby carriage, or first to walk with stilts. Regular vehicular traffic began the next day costing motorist $0.50 each way to drive across. Oddly enough, this sum was quite substantial during the depression years for a bridge toll. It would amount to over $18.00 in today’s money, however, on July 1, 2023, the bridge tolls will top out at $9.75, but are required for only one way—coming south into the city.
The Day the Bridge Flattened: On May 24, 1987, the city celebrated the 50th anniversary of the opening of the Golden Gate Bridge. The bridge was again closed to vehicular traffic for the celebration that drew nearly 1,000,000 visitors in total. About 300,000 at one time were congested on the bridge, and the huge amount of added weight caused the bridge to flatten out by about seven feet at the middle. The condition was temporary, as the bridge was designed to maintain a certain element of flex as normal traffic conditions provide an ebb and flow to the stress on the suspension cables. The added weight may have caught officials by surprise, but it was estimated not to have exceeded the 40% stress limit built into the suspension cable system. None the less, for the 75th anniversary celebration that took place on May 27, 2012, pedestrian traffic was restricted.
Conclusion: Each year I travel up the coast from my home in Orange County to Napa and Sonoma Counties in Northern California to visit friends and family. I generally cross the bridge at least once during these trips, and usually take a few minutes to admire the exquisite view of the bridge and San Francisco from the Marin side.
Sources: When the Golden Gate Bridge Flattened by 7 Feet—and Other Facts About the San Francisco Icon, Lindsey Konkel, History.com, July 12, 2019.
Wikipedia, Golden Gate Bridge.