The large majority of American megastructures we’ve spoken about on this channel are on the east coast. The Empire State Building, The Pentagon, and the Twin Towers, for example. However, today we’re discussing the most iconic structure in the western United States: The Golden Gate Bridge.
Located on the edge of San Francisco, the massive bridge is famous for its unique orange color and decorative aspects. But beyond its iconic image, it was also immensely practical. Despite all that, the world didn’t actually know of the men responsible for designing it until a couple decades ago. According to current estimates, it may be by sheer luck that it never collapsed in an earthquake. One thing is for sure— it’s a sight to behold. Let’s get started.
San Francisco sits on the tip of a small peninsula, creatively named the San Francisco peninsula. One mile across the water from San Francisco, on the California mainland, is Marin County. This one-mile-wide strait is called the Golden Gate, as it leads from the endless Pacific Ocean to a complex of bays, the largest of which is called…San Francisco Bay.
San Francisco has been a population center for well over a century, but there isn’t a ton of habitable land in the city itself. The mid-19th-century ushered in the California gold rush, and the Bay Area’s population ballooned. Within San Francisco, the number of residents tripled in the ten years from 1850 to 1860, from 49,000 to 150,000. While San Francisco was, and still is, the economic center for the region, many of the town’s workers lived across the strait in Marin County.
Following the population boom, the first consistent ferry service was established in 1867 by the Sausalito Land and Ferry Service. The trip across the strait took about 30 minutes, but the boats’ limited capacity slowed workers’ flow into the city. Around this time, the area’s most ambitious thinkers proposed building a bridge across the Golden Gate, but the idea was cast aside as impossible and preposterous. After all, the 2,000 meter Golden Gate strait was known for its inhospitable conditions, like 97 km/h winds, thick fog, and a seafloor over 100 meters deep.
By the 20th-century, though, attitudes began to change. San Francisco was continuing to grow, but the lack of easy access was stunting that growth. It became the largest city in America to rely on a ferry for such a considerable portion of its workforce. In 1916, the bustling town hosted a world fair marked by ambitious, futuristic proposals on developing the city. With this aura of creative ambition in full swing, a man named James Wilkins published an op-ed in the local paper calling for the city to finally take the plunge and build the bridge. San Francisco’s city engineer looked into the scheme and estimated that the cost would exceed 100 million dollars (2.3 billion in 2020), far above a feasible budget. But, he also requested proposals from anyone who could conceive of a more cost-efficient design.
This call for input caught the attention of a man named Joseph Strauss, an ambitious engineer who wrote poetry in his free time. Strauss was no stranger to designing massive bridges, as, for his Master’s thesis, he developed a plan for an 89-kilometer bridge to cross the Bering Strait. While that design was obviously never built, he had successfully completed about 400 bridges through the US, most of which were smaller-scale drawbridges.
Strauss’s design would cut costs by more than half, so he was selected as the project architect under the stipulation that he would work with a team of engineers who were more experienced with such large-scale projects. But, while the plan was now set in motion, the battle for building the bridge was just beginning.
Approval and Financing
Strauss would spend the next decade growing support for the bridge and facing opposition from all directions. The US Navy and the Department of War worried that the bridge would affect ship traffic or even become a target for bombings, which would cut off the Navy’s ships in the Bay Area from the Pacific Ocean. The Southern Pacific Railroad was perhaps the most influential opponent, as they operated the local ferry service. Local environmentalists argued that the bridge would ruin the area’s natural beauty, and other locals feared the tax implications of such an expensive project. Working in tandem, these foes almost succeeded in blocking the bridge’s construction, but Strauss put up a fight and found support wherever possible.
He filled the newspapers with op-eds and traveled throughout Northern California to speak to labor unions, booster clubs, and politicians. One of Strauss’s most important allies was the growing automobile industry, which saw the bridge as a critical step in convincing locals to splurge on cars. By the late 1920s, the project was officially approved, and the land was granted for the structure, but the fight wasn’t over. The next step was financing the project, and the timing couldn’t have been worse.
With the stock market crash of October 1929 came the Great Depression, and money for financing the project was suddenly lost. California’s government approved the issuance of 30 million dollars worth of bonds the following year, which would be worth almost half-a-billion today, but nobody was willing to put forward that amount of money. After two years of traveling the country getting rejected by financiers, Strauss was on his last leg. So, he turned to Amadeo Giannini, the president of Bank of America and a long-time resident of San Francisco. Strauss pleaded with Giannini, claiming that the state would scrap the project if they didn’t have funding soon. His appeal worked, with Giannini and Bank of America buying all of the bonds, supposedly in an attempt to reinvigorate the local economy. Finally, after 15 years of planning, pleading, and peddling, the Golden Gate Bridge had a clear path forward.
The Design Team
Apart from his role as the man who got the Golden Gate Bridge approved and financed, Joseph Strauss also was the project’s chief engineer. However, this may have been little more than a title. Strauss’s plan was chosen because it was so much cheaper than the city government projected, but it turned out that the city board wasn’t actually a fan of his design. His first mockup included two double cantilever spans connected by a central suspension segment, and this was rejected because it was apparently too ugly. So, despite Strauss’s title, many modern historians and engineers claim that the bridge was mostly designed by three other men.
The first was an engineer named Leon Moisseiff, who was most notable for his work on the Manhattan Bridge in New York. Moisseiff was the leading proponent of building a large suspension bridge, an ambitious decision in and of itself, as no suspension bridge had ever crossed such a large body of water. Moisseiff was attached to the project early on, as the city board felt his vision was much more visually pleasing.
Another key contributor was Irving Morrow, an architect who had spent most of his career planning residential spaces. Though Morrow was something of an unknown at the time, he contributed most of the details that made the bridge such an icon, personally designing the shape of the bridge’s towers, their Art Deco elements, and the entire structure’s lighting scheme. Most importantly, he is the one who chose the bridge’s color, thankfully rejecting a proposal by the US Navy to paint it black with yellow stripes.
Finally, Moisseiff’s right-hand man was an engineer named Charles Ellis. Though not credited with the title, Ellis is considered by most to have been the project’s principal engineer. This meant that he was responsible for the bridge’s overall structural design, including dealing with the intense winds that flooded through the Golden Gate.
Despite, or perhaps because of, assembling this dream team, tensions between the men were often high. Strauss’s ego, which had been so essential for getting the project approved, made it difficult for him to give up so much control. He suffered from bouts of paranoia, often theorizing that the three men were conspiring to get him removed from the project. Eventually, Strauss fired Ellis when he uncovered that the man communicated with Moisseiff, who, remember, was Ellis’s supervisor, behind his back. Despite his firing, Ellis continued to contribute 70 hours a week for the following years before transitioning to academia and becoming a global authority on structural design.
However, one nasty part of Strauss’s attitude revealed itself in his inability to credit anyone else for their contributions. Following the bridge’s completion, Strauss was celebrated as a local hero, with the city erecting a large statue to the man. The rest of the team received little to no credit whatsoever. Not until the late 20th-century did historians reveal that Strauss’s contributions were mostly limited to getting the project approved. Now, Ellis, Moisseiff, and Morrow are recognized as crucial contributors alongside Strauss in designing and building the Bay Area icon.
Construction and Opening
Construction finally began on the bridge on January 5th, 1933. Altogether, the bridge took just over four years to build, eventually finishing on May 27th, 1937. The total cost was 35 million dollars ($523 million in 2019 dollars), placing it about 1 million under the original budget.
The builders’ first task was to construct the anchorages for the two soaring towers that would bear most of the bridge’s weight. The anchorage near San Francisco stood 305 meters from the coast, while the other was on Marin County’s shoreline. The two anchorages required workers to blast excavations in the straits seafloor and pump out 9.7 million gallons of water before pouring concrete to support the structures.
Each of the two towers stands 227 meters (746 feet) above the water, the tallest of any suspension bridge towers until the Mezcala Bridge was completed in Mexico in 1993. At the top of each tower, embedded in concrete, are two main cables that run the bridge’s entire length. Each of those two cables comprises exactly 27,572 strands of wire, or over 130,000 km worth of wire. 250 pairs of vertical suspender ropes connect the wires to the bridge’s roadway.
While construction went relatively smoothly for the duration, there was one major accident. In the final year of building, a set of scaffold collapsed, killing ten men. However, the project could have gone much worse if not for Strauss’s contribution of placing safety netting beneath scaffolds to catch falling workers. Believe it or not, this was considered a groundbreaking innovation at the time. This movable safety netting saved lives throughout the rest of the project, but, in the one circumstance, it was unable to bear the weight of the collapsed scaffolding.
The bridge stands 67 meters (220 feet) above the water and, from abutment to abutment, is over 2,700 meters (8,900 ft) long. Its main body is 1,300 meters (4,200 feet), which gave it the title of world’s longest suspension bridge until it was surpassed in 1964.
Following the bridge’s completion, a week of opening ceremonies began, marked by President Franklin Roosevelt sending a “telegram to the world” that the massive structure was finally opened. The celebration was raucous, with more than 200,000 people walking across the bridge on the first day of opening. And the people had much to celebrate. Though always a lovely and unique city, San Francisco had lacked a symbol of their statue. With the bright orange Golden Gate Bridge, they had their icon.
Challenges and Renovations
While the simple act of crossing the Golden Gate strait was impressive in and of itself, the region’s geography and climate forced the engineering team to overcome a few obstacles.
The bridge was designed to safely withstand winds of up to 109 km/h (68 mph), but in 1951 the area was hit with 111 km/h winds, forcing the bridge to shut down for the day. This windstorm revealed rolling instabilities and excessive swaying, which could lead to a complete collapse in the worst of circumstances. In fact, a suspension bridge in Tacoma, Washington, designed by Joseph Strauss, had collapsed from wind in 1940, less than six months after it had opened. So, after seeing the excessive swaying, the bridge was reinforced with additional diagonal bracing on the trusses.
Despite the additional reinforcement, the bridge has still been subject to shutdown for winds exceeding 109, closing briefly in December of 1982 and 1983 during brief periods of winds around 115 km/h. In 2019, though, as part of a larger renovation project, many slats on the bridge’s sides were retrofitted with more flexible materials, creating a more aerodynamic structure. Now, the bridge can safely withstand winds up to 160 km/h (100 mph), which has never been recorded in that area. Strangely enough, the only adverse effect of the new design is that the slats vibrate in strong winds, creating a humming noise loud enough to be heard by residents in Marin County, across the bridge from San Francisco.
The most significant complete renovation in the bridge’s history came in the 1980s. As we mentioned, the Bay Area is notorious for its dense fog and mists, which carry corrosive saltwater into the air. The Golden Gate Bridge’s original deck was made of rebar-enforced concrete, which can cause corrosion, palling, and eventually rusting of the metal rebar when mixed with saltwater. Over four years, the entire bridge deck was replaced without ever shutting off traffic access. Instead of the rebar concrete, the workers installed steel orthotropic deck panels, which are 40% lighter, stronger, and much more resistant to saltwater. The project cost an estimated 68 million dollars.
The final significant engineering challenge was the bridge’s location near the San Andreas Fault. This fault places the entire Bay Area in the middle of one of the world’s hottest seismic zones. In fact, some seismologists predict that a long-overdue super-quake will hit the city in the coming decades. While the bridge was initially viewed as indestructible by earthquakes, it turned out this assumption was far from accurate. In fact, a 98-meter high support arch on the San Francisco side of the bridge was vulnerable to collapse in the event of a large quake, but the city has been lucky to avoid such catastrophes in the years following the bridge’s completion.
A reinforcement project is underway currently and will soon surpass the surface upgrade as the most expensive project, coming in at about half-a-billion dollars, though the project includes other components.
Despite its beauty and magnificence, the Golden Gate Bridge is famous for one thing that can only be called a tragedy— it is the most frequently used suicide spot in the world. With most of the deck standing 75 meters (245 feet) above the water, jumpers fall for four seconds, often reaching alarmingly high speeds of 120 km/h. At such high rates, most jumpers are killed on impact. But, after decades of debate, the addition of a suicide prevention net was finally approved. The net extends 6 meters off the bridge and is supported by stainless steel, effectively making it impossible for jumpers to reach the water. Though initially due for completion in 2019, the construction has been delayed by a shift in the contracting company’s ownership. The net is expected for completion in 2023.
Altogether, the Golden Gate Bridge’s story is an odd one, perhaps reminiscent of the idiosyncratic city it calls home. It remains a symbol of the distances that humankind can cross through creativity, ingenuity, and determination.