The massive canyon formed by the Colorado River where it joins Nevada and Arizona already boasts one iconic piece of engineering: the Hoover Dam. The new bridge, just half a kilometre downriver from the dam, will only add to the splendour of the area and give North America its first composite concrete deck arch bridge.

The new crossing is badly needed. Currently, a narrow two-lane highway runs along the top of the dam. The approaches are winding and treacherous. Congestion is terrible, the crossing is on one of the area’s major routes, US Highway 93, and handles both through-traffic and Hoover Dam tourists.

Security concerns since 9/11 have led to a lorry ban on the crossing which has increased disruption. The ambitious Hoover Dam Bypass scheme – with the new bridge at its centre – should ease these problems when it opens to traffic in 2008.

The bridge alone will cost $114m. At 580m long and rising almost 275m above the Colorado river, it has brought some difficult construction challenges. Workers have had to contend with temperatures reaching 46 degrees centigrade, as well as strong and unpredictable winds and dangerous terrain with terrifying drops.

In September 2006, strong winds sent two enormous construction cranes crashing into Highway 93 – amazingly, with no loss of life! There are also a number of environmental issues to consider, including managing the endangered desert tortoises that inhabit the region, alongside protecting a herd of mountain sheep who reside close to the construction site.