The East Span Bridge of San Francisco

Self anchored bridge

The east span bridge in san Francisco

                The thought of a self anchored bridge is really amazing. It’s a bridge that isn’t held up by ropes suspended from the ground, it’s a bridge that uses a single rope to hold its own weight using its self as an anchor. The world’s current largest SAS (Self anchored suspension bridge) sets in South Korea with a distance of 300 meters. There currently is a bridge under construction in San Francisco which is 385 meters.

                The SAS was originated by an Austrian engineer Josef Langer in 1859 and an American engineer Charles Bender in 1867. The very first SAS appeared in Germany over the Rhine river in the first half of the 20th century.   

The reconstruction of the east span bridge is due to a major earthquake in 1987. It destroyed the bridge which was used often. It was a part of interstate 80. The bridge will stand 525ft tall, 100ft from the ocean. Its 10 lanes wide can hold 500,000LBS. Construction began in 2002 and was expected to end in 2007 but is now expected to be open to traffic in 2013. The bridge cost an estimated 6.3 billion dollars.

 

The newly designed east span bridge has a fail-safe system. If there were an earthquake large enough to damage the bridge, it would damage a little  capsule. It can be replaced within a matter of a couple of hours. The new bridge was designed to withstand well over the 6.9 magnatude earth quake that destroyed the last one with only minor damages.