The Golden Gate Bridge was the longest suspension bridge span in the world when it was completed during the year 1937, and has become one of the most internationally recognized symbols of San Francisco, California, and of the United States. Since its completion, the span length has been surpassed by eight other bridges. It still has the second longest suspension bridge main span in the United States, after the Verrazano-Narrows Bridge in New York City.
Construction began on January 5, 1933. The project cost more than $35 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.The bridge-opening celebration began on May 27, 1937 and lasted for one week. The day before vehicle traffic was allowed, 200,000 people crossed by foot and roller skate.
The weight of the roadway is hung from two cables that pass through the two main towers and are fixed in concrete at each end. Each cable is made of 27,572 strands of wire. There are 80,000 miles (129,000 km) of wire in the main cables. The bridge has approximately 1,200,000 total rivets.
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 and repainting the bridge with zinc silicate primer and vinyl topcoats.Since 1990 Acrylic topcoats have been used instead for air-quality reasons. The program was completed in 1995 and it is now maintained by 38 painters who touch up the paintwork where it becomes seriously eroded.
The Golden Gate Bridge is not only the most popular place to commit suicide in the United States but the most popular in the entire world.The deck is approximately 245 feet (75 m) above the water. After a fall of approximately four seconds, jumpers hit the water at some 76 miles per hour (122 km/h). At such a speed, water has proven to take on properties similar to concrete. Because of this, most jumpers die on their immediate contact with the water. The few who survive the initial impact generally drown or die of hypothermia in the cold water.
Since its completion, the Golden Gate Bridge has been closed due to weather conditions only three times: on 1 December 1951, because of gusts of 69 mph (111 km/h); on 23 December 1982, because of winds of 70 mph (113 km/h); and on 3 December 1983, because of wind gusts of 75 mph (121 km/h).
Modern knowledge of the effect of earthquakes on structures led to a program to retrofit the Golden Gate to better resist seismic events. The proximity of the bridge to the San Andreas Fault places it at risk for a significant earthquake. Once thought to have been able to withstand any magnitude of foreseeable earthquake, the bridge was actually vulnerable to complete structural failure (i.e., collapse) triggered by the failure of supports on the 320-foot (98 m) arch over Fort Point. A $392 million program was initiated to improve the structure’s ability to withstand such an event with only minimal (repairable) damage. The retrofit’s planned completion date is 2012.
Doyle Drive replacement project
The elevated approach to the Golden Gate Bridge through the San Francisco Presidio is popularly known as Doyle Drive. Doyle Drive, dating back to 1933 was named after Frank P. Doyle, director of the California State Automobile Association.The highway carries approximately 91,000 vehicles each weekday between downtown San Francisco and suburban Marin County. However, the road has been deemed “vulnerable to earthquake damage”, has a problematic 4-lane design, and lacks shoulders.For these reasons, a San Francisco County Transportation Authority study recommended that the current outdated structure be replaced with a more modern, efficient, and multimodal transportation structure. Construction on the $1 billion replacement, known as the Presidio Parkway, began in December 2009 and is expected to be completed in 2013.