Golden Gate Bridge, San Francisco Bay

Conception

Although the idea of a bridge spanning the Golden Gate was not new, the proposal that eventually took root was made in a 1916 San Francisco Bulletin article by former engineering student James Wilkins. San Francisco's City Engineer estimated the cost at $100 million, impractical for the time, and fielded the question to bridge engineers of whether it could be built for less. One who responded, Joseph Strauss, was an ambitious but dreamy engineer and poet who had for his graduate thesis designed a 55-mile (89 km) long railroad bridge across the Bering Strait. At the time, Strauss had completed some 400 drawbridges, but mostly inland and nothing on the scale of the new project. Strauss' initial drawings were for a massive cantilever on each side of the strait, connected by a central suspension segment, which Strauss promised could be built for $17 million. Strauss' design was widely derided as ugly.Local authorities agreed to proceed only on the assurance that Strauss alter the design and accept input from several consulting project experts.[citation needed] A suspension bridge design was considered the most practical, because of recent advances in metallurgy.Strauss spent more than a decade drumming up support in Northern California. The bridge faced opposition, including litigation, from many sources. The Department of War was concerned that the bridge would interfere with ship traffic. Unions demanded guarantees that local workers would be favored for construction jobs. Southern Pacific Railroad, one of the most powerful business interests in California, opposed the bridge as competition to its ferry fleet and filed a lawsuit against the project, leading to a mass boycott of the ferry service. In May 1924, Colonel Herbert Deakyne held the second hearing on the Bridge on behalf of the Secretary of War in a request to use Federal land for construction. Deakyne, on behalf of the Secretary of War, approved the transfer of land needed for the bridge structure and leading roads to the "Bridging the Golden Gate Association", and both San Francisco County and Marin County, pending further bridge plans by Strauss. Another ally was the fledging automobile industry, which supported the development of roads and bridges to increase demand for automobiles.The bridge earned its name, Golden Gate Bridge, after a mention of it in 1927 by San Francisco city engineer Michael O'Shaughnessy.

Design

Strauss was Chief Engineer in charge of overall design and construction of the bridge project. However, because he had little understanding or experience with cable suspension designs, responsibility for much of the engineering and architecture fell on other experts.Irving Morrow, a relatively unknown residential architect, designed the overall shape of the bridge towers, the lighting scheme, and Art Deco elements such as the streetlights, railing, and walkways. Morrow also chose the famous International Orange color.Senior engineer Charles Alton Ellis, collaborating remotely with famed bridge designer Leon Moisseiff, was the principal engineer of the project. Moisseiff produced the basic structural design, introducing his "deflection theory" by which a thin, flexible roadway would flex in the wind, greatly reducing stress by transmitting forces via suspension cables to the bridge towers. Although the Golden Gate Bridge design has proved sound, a later Moisseiff design, the original Tacoma Narrows Bridge, collapsed in a strong windstorm soon after it was completed, due to an unexpected resonance mode caused by a too-thin roadway and unexpected wind forces.Ellis was a Greek scholar and mathematician who became a University of Illinois professor of engineering despite having no engineering degree. He became an expert in structural design, writing the standard textbook of the time. Ellis did much of the technical and theoretical work that built the bridge but got none of the credit in his lifetime. In November, 1931, Strauss fired Ellis and replaced him with a former subordinate, Clifford Paine, ostensibly for wasting too much money sending telegrams back and forth to Moisseiff. Ellis, obsessed with the project and unable to find work elsewhere during the Depression, continued working 70 hours per week on an unpaid basis, eventually turning in ten volumes of hand calculations.With an eye toward self-promotion and posterity, Strauss downplayed the contributions of his collaborators who, despite receiving little recognition or compensation, are largely responsible for the final form of the bridge. He succeeded in having himself credited as the person most responsible for the design and vision of the bridge. Only much later were the contributions of the others on the design team properly appreciated. In May 2007, the Golden Gate Bridge district issued a formal report on 70 years of stewardship of the famous bridge, and decided to right an old wrong by giving Ellis major credit for the design of the bridge.

Finance

The Golden Gate Bridge and Highway District, authorized by an act of the California Legislature, was incorporated in 1928 as the official entity to design, construct, and finance the Golden Gate Bridge. However, after the Wall Street Crash of 1929, the District was unable to raise the construction funds so it lobbied for a $35 million bond measure. The bonds were approved in November, 1930, by votes in the counties affected by the bridge. The construction budget at the time of approval was $30.1 million. However, the District was unable to sell the bonds until 1932, when the founder of San Francisco-based Bank of America agreed on behalf of his bank to buy the entire issue in order to help the local economy.

Construction

Construction began on January 5, 1933. The project cost over $26 million.Strauss remained head of the project, overseeing day-to-day construction and making some groundbreaking contributions. A graduate of the University of Cincinnati, he had placed a brick from his alma mater's demolished McMicken Hall in the south anchorage before the concrete was poured. He innovated the use of movable safety netting beneath the construction site, which saved the lives of many otherwise unprotected steelworkers. Of eleven men killed from falls during construction, ten were killed (when the bridge was near completion) when the net failed under the stress of a scaffold that had fallen. Nineteen others who were saved by the net over the course of construction became proud members of the (informal) Halfway to Hell Club.The project was finished by April 1937, $1.3 million under budget.

Specifications

The center span was the longest among suspension bridges until 1964 when the Verrazano-Narrows Bridge was erected between the boroughs of Staten Island and Brooklyn in New York City. The Golden Gate Bridge also had the world's tallest suspension towers at the time of construction, and retained that record until more recently. In 1957, Michigan's Mackinac Bridge surpassed the Golden Gate Bridge's length to become the world's longest two tower suspension bridge in total length between anchorages.

Structure

The bridge has approximately 1,200,000 total rivets.

Aesthetics

Despite its red appearance, the color of the bridge is officially an orange vermilion called international orange. The color was selected by consulting architect Irving Morrow because it blends well with the natural surroundings yet enhances the bridge's visibility in fog.The bridge is widely considered one of the most beautiful examples of bridge engineering, both as a structural design challenge and for its aesthetic appeal. It was declared one of the modern Wonders of the World by the American Society of Civil Engineers. According to Frommer's travel guide, the Golden Gate Bridge is "possibly the most beautiful, certainly the most photographed, bridge in the world" (although Frommers also bestows the "most photographed" honor on Tower Bridge in London, England).Aesthetics was the foremost reason why the first design of Joseph Strauss was rejected. Upon re-submission of his bridge construction plan he added details, such as lighting, to outline the bridge's cables and towers.The Golden Gate Bridge has a similar sister bridge in Lisbon, Portugal. The red-painted Ponte 25 de Abril (25th April Bridge) has a total length of 2,278 m (7,470 ft) with a central span of 1,013 m (3,320 ft).

Paintwork

The bridge was originally painted with red lead primer and a lead-based topcoat, which was touched up as required. In the mid-1960s, a program was started to improve corrosion protection by stripping the original paint off and repainting the bridge with zinc silicate primer and, originally, vinyl topcoats. Acrylic topcoats have been used instead since 1990 for air quality reasons. The program was completed in 1995, and there is now maintenance by 38 painters to touch up the paintwork where it becomes seriously eroded.