April 18, 2013 • 796 views
An Engineering Feat …. San Francisco’s Golden Gate Bridge is one of California’s greatest tourist attractions. It represents the symbol of the City by the Bay and is its most recognizable site and image in a city filled with iconic symbols. But it not only took hard work and years to build, but it also incorporated new and innovative engineering designs to complete. After voters approved bond funding a bridge to be built spanning Golden Gate Strait and connecting San Francisco and Marin counties, Joseph Strauss was selected as the Chief Engineer for the project. Strauss’ specialty was drawbridges and his design called for a suspension span, though he never had built one. Named in 1929, Strauss began to pick his team of engineers, including a local architecture firm named Morrow & Morrow. In spite of the Great Depression, construction began on the bridge project as the need to connect San Francisco with Marin County to the North outweighed the Bridges’ cost. As many projects were stalling during this time period, Strauss tried to correct the situation before finances would affect the project. Strauss met with Bank of America chairman of the board, A. P. Giannini and tried to persuade him to buy the $35 Million in Bonds which was still outstanding. After a long debate Giannani asked Strauss how long his bridge would last. Stauss replied “Forever”, to which Giannani replied that he would buy the bonds because California needed the bridge. The rest is history. Strauss’ design called for 4,200 foot long suspension span, a span that had not been attempted before. The design also called for two towers standing 500 feet above the roadway, and would be the first built in open water. The foundation for the towers sits more than 1,100 feet from the shoreline. There are two main cables running down from the south tower and 250 suspender ropes made of vertical steel strands which encase the main cable. The Art Deco design, originally applied by Irving Morrow, included the International Orange color and design architecture which was highly popular in the 1930’s. Construction began on January 5, 1933 and opened to automobile traffic on May 28, 1937. The bridge is 1.7 miles long and has a weight of 887,000 tons. The diameter of the main cable is 36 inches and is 7,650 feet in length. Over 83,000 tons of steel and 339,000 cubic yards of concrete were used. Since 1937, approximately 1.9 billion cars have crossed the bridge. The original cost of $35 million plus $39 million in interest was repaid in 1971 from revenues generated from toll charges. In spite of challenging working condition, including stiff cross winds and freezing temperature, the bridge was successfully completed. Its impressive image is a memorable site to see and serves as a monument to the engineers and construction workers who worked on the project for nearly eight years. Indeed this was a remarkable engineering feat….