"The Golden Gate Bridge: Beautiful Under All Light Conditions," by Alpha Unit

This year is the 75th anniversary of the Golden Gate Bridge, the technical and artistic marvel that is one of this country’s most famous landmarks. It’s been declared one of the modern Wonders of the World by the American Society of Civil Engineers – and seen by some as possibly the most beautiful bridge in the world. Before the bridge was built, the only practical way to get from San Francisco to Marin County was by ferry. This began in the 1800s. Southern Pacific Railroad came to operate the ferries – a profitable and vital operation for the regional economy. People had long considered building a bridge to connect San Francisco and Marin County. The first proposal to really take hold was made in 1916. An engineer named Joseph Strauss made a pitch to local authorities, designs and all. A suspension-bridge design was considered most practical. Strauss actually spent over 10 years trying to gain support for a bridge. The Department of War was afraid it would interfere with ship traffic. Southern Pacific Railroad didn’t want any competition for its ferry fleet and filed a lawsuit. But among allies was the automobile industry, which supported the development of roads and bridges for clear reasons. The state legislature passed the Golden Gate Bridge and Highway District Act in 1923. Construction began in January of 1933, with Strauss as chief engineer. The contractor was the McClintic-Marshall Construction Company, a subsidiary of Bethlehem Steel. The call went out for workers. Since the Great Depression was well underway by then, there was no shortage of men seeking work on the bridge. All hiring had to be done through the Ironworkers Union Local 377 in San Francisco. There weren’t enough ironworkers in the city, so men were recruited from all over. But before any construction could actually begin on the bridge, they needed divers to begin the crucial underwater construction process. This would be especially difficult. As one author described it:

The narrow strait between Marin County and San Francisco is one of the world’s most tumultuous bodies of water. Up to 335 feet deep and only a mile and a quarter wide, the Golden Gate is the largest California coastal opening – a portal into which the Pacific Ocean surges. Powerful currents also flow in the opposite direction as water from many of Northern California’s freshwater rivers and streams rushes into San Francisco Bay. The freshwater flow collides with the incoming Pacific, creating complex and violent currents.

Workers would have to erect a pier more than 1,000 feet out in the middle of the Gate – the first bridge support ever constructed in the open ocean. Divers had to begin by blasting away rock for the south tower’s supports. This involved placing blasting tubes into position and securing them while trying not to be swept away in the current. They had to go as deep as 90 feet below the surface to remove detonation debris using underwater hoses that exerted 500 pounds of hydraulic pressure.

The Gate’s changing currents afforded workers only a narrow window of dive time. The men were restricted to submerging for four 20-minute periods per day. With the construction team’s tight schedule, divers were often forced to surface before having sufficient time to decompress, increasing the likelihood that they would develop caisson disease… also known as “the bends.”

The divers guided beams, panels, and 40-ton steel forms into position, often having to feel their way due to murky water and fast-changing currents, and while wearing bulky diving suits. Yet the danger didn’t deter men from this underwater work. It was a steady, well-paying job – not easy to come by during the Depression. When construction started on the bridge itself, the first workers excavated three and a quarter million cubic feet of dirt and poured enormous amounts of concrete for the bridge’s two anchorages. The 12-story high anchorages were designed to secure 63 million pounds – twice the pull of the bridge’s main cables, we are told. In November of 1933 the first tower began to go up. Prefabricated sections were fit into place and riveted together by 4-man rivet gangs. After both towers were complete in June of 1935, workers built catwalks and started spinning the cables for the bridge. The engineering company John Roebling and Sons oversaw cable construction. This firm had built many of the world’s longest bridges, including the Brooklyn Bridge 52 years earlier. It had developed a technique of spinning cables on site.

To spin the cables, 80,000 miles of steel wire…were bound in 1,600-pound spools and attached to the bridge’s anchorage. A fixture within the anchorage called a strand shoe was used to secure a “dead wire” while a spinning wheel, or sheave, pulled a “live wire” across the bridge. Once it reached the opposite shore of the Gate, the live wire was secured onto the strand shoe, and the wheel returned with another loop of wire to begin the process again.

Hundreds of wires, each roughly the diameter of a pencil, were bound together into strands. Hydraulic jacks then bundled and compressed 61 strands to make a cable. Each of the main cables is just over 3 feet in diameter. The work was laborious and had to be done to ensure the correct tension and balance in the cables. As for the deck, or roadway, of the bridge, traveling cranes working from each tower laid down the steel decking that would undergird the roadway. The first concrete was poured for the roadway in January of 1937. Opening day for the Golden Gate Bridge was May 27, 1937. An estimated 200,000 people came for the celebration. As one of them later recalled:

The weather at the Golden Gate was typical for San Francisco in May: foggy, windy, and cold, but that didn’t bother anyone. They would always remember they had walked across the Golden Gate Bridge on opening day. You were encouraged to wear a costume or the Official Hat with its tassels. But it was the Depression. If you couldn’t afford the hat, a bandana would do just fine.

The workers who constructed the bridge were executing the design of what The San Francisco Chronicle calls an engineering dream team. Although Joseph Strauss was chief engineer, he had little understanding or experience with cable-suspension designs, so other experts were given responsibility for much of the engineering and architecture. Charles Alton Ellis was the structural engineer and mathematician responsible for the structural design of the bridge. He did all the mathematical calculations that made the bridge possible. Leon Moisseiff was a leading suspension bridge engineer in the 1920s and 1930s. He was known for his work on deflection theory, which held that the longer bridges were, the more flexible they could be. Ellis applied Moisseiff’s theories in the design of the bridge. Othmar Ammann was a structural engineer who had designed the George Washington Bridge in New York City. He served on the board of engineers for the Golden Gate Bridge. Charles Derleth was the dean of the college of engineering at UC Berkeley. He served on the advisory board with Moisseiff and Ammann. Andrew Lawson was a professor of geology at UC Berkeley. He was the first person to identify and name the San Andreas Fault. He was a consulting geologist and seismic expert for the construction of the bridge. Irving Morrow was the consulting architect for the bridge. Morrow graduated from the newly founded UC Berkeley architectural program in 1906. Joseph Strauss hired him to design the architectural treatment of the bridge. He was influenced by Art Deco design, but his most famous contribution to the Golden Gate Bridge is its distinctive burnt red-orange hue called International Orange. “The tone is beautiful under all light conditions,” one observer admitted.


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