標題: Taking shape, the new bridge at the Hoover Dam (胡佛水庫新懸張橋) [打印本頁] 作者: d2900 時間: 2009-12-4 06:46 PM 標題: Taking shape, the new bridge at the Hoover Dam (胡佛水庫新懸張橋)
THE WIDER VIEW: Taking shape, the new bridge at the Hoover Dam
Creeping closer inch by inch, 900 feet above the mighty Colorado River, the two side of a $160 million bridge at the Hoover Dam slowly takes shape.
The bridge will carry a new section of US Route 93 past the bottleneck of the old road which can
be twisting and winding around and across the dam itself.
When complete, it will provide a new link between the states of Nevada
and Arizona .
In an incredible feat of engineering, the road will be supported on the two massive concrete
arches which jut out of the rock face.
The arches are made up of 53 individual sections each 24 feet long which have been
cast on-site and are being lifted into place using an improvised high-wire crane strung between temporar! y steel pylons.
The arches will eventually measure more than 1,000 feet across. At the moment, the structure looks
like a traditional suspension bridge. But once the arches are complete, the suspending cables on each side
will be removed. Extra vertical columns will then be installed on the arches to carry the road.
The bridge has become known as the Hoover Dam bypass, although it is officially called the
Mike O'Callaghan-Pat Tillman Memorial Bridge, after a former governor of Nevada and
an American Football
player from Arizona who joined the US Army and was killed in Afghanistan.. Work on the bridge started in 2005
and should finish next year. An estimated 17,000 cars ! and trucks will cross it every day.
The dam was started in 1931 and used enough concrete to build a road from New York to San Francisco .
The stretch of water it created, Lake Mead , is 110 miles long and took six years to fill.
The original road was opened at the same time as the famous dam in 1936.
An extra note: The top of the white band of rock in Lake
M ead is the old waterline prior to the drought
and development in the Las Vegas area. It is over 100 feet above the current water level.