Taking shape: the new bridge at the Hoover Dam

Creeping  closer inch by inch, 900 feet above the mighty  Colorado River, the two sides of a
$160  million bridge at the Hoover Dam slowly take  shape. 

When  complete, the bridge will provide a new link  between the states of Nevada  and   Arizona . 
In  an incredible feat of engineering, the road will  be supported on 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
temporary  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.