"On This Day" In Engineering History

On this day in engineering history, the Golden Gate Bridge was opened to pedestrians, prompting 18,000 people to stand in line for a chance to cross what the San Francisco Chronicle dismissed as "a thirty-five million dollar steel harp". A day later, the world's largest suspension bridge was opened to automobile traffic as U.S. President Franklin D. Roosevelt announced the engineering achievement from the White House with the stroke of a telegraph key.

Today, nearly 2 million vehicles have crossed California's Golden Gate Bridge, a 9,000-ft. long structure which spans the Golden Gate, a deep but narrow strait at the mouth of San Francisco Bay. Although this symbol of the city no longer claims the title of "the world's longest suspension bridge", the Golden Gate Bridge has withstood floods, earth slides, and even strongest earthquake to rock the Bay Area since 1906.

Cost Estimates and Construction

Construction on the Golden Gate Bridge began on January 5, 1933, nearly 20 years after San Francisco's chief engineer, Michael O'Shaughnessy, received an original cost estimate for the then-sizable sum of $100 million (USD). Fortunately, O'Shaughnessy later received a more modest, $17-million estimate from Joseph Strauss, a structural engineer and bridge builder who had once worked for Ralph Modjeski.

When local authorities demanded substantial changes to Strauss's design, however, the bridge builder recruited Irving Morrow, a little-known residential architect, and Charles Alton Ellis, a Greek scholar and mathematician who lacked an engineering degree. Although Ellis was fired in 1931, Morrow left his mark on the Golden Gate Bridge by designing the shape of the bridge towers and selecting its now-famous "international orange" color. According to the Golden Gate Bridge Research Library, there are approximately 600,000 rivets in each of the Bridge's towers.

From 1933 to 1937, ten contractors and subcontractors labored on the Golden Gate Bridge. Although the number of people who worked on the structure remains unknown, eleven men lost their lives – setting a new record in a business where one man killed for every million dollars spent had been the norm. Fortunately, the lives of 19 other workers were saved by a massive safety net which was suspended under the floor of the Bridge from end to end. The hard hat was also invented during construction.

The union steel workers who built the Golden Gate Bridge worked with metal from Bethlehem Steel plants in New Jersey, Maryland and Pennsylvania. Loaded onto rail cars, this steel was transported to Philadelphia and then shipped through the Panama Canal to San Francisco, where it arrived in time to coincide with various construction phases.

Resources:

http://www.wired.com/science/discoveries/news/2008/05/dayintech_0527

http://goldengatebridge.org/research/facts.php

http://en.wikipedia.org/wiki/Golden_Gate_Bridge

http://en.wikipedia.org/wiki/Joseph_Strauss