The John J Audubon Bridge in the US, believed to be the longest cable-supported bridge in North America, will open to traffic in 2011.

The bridge across the Mississippi River, despite an original estimate of $50m, is thought to have now cost $408m, according to 2theadvocate.com.

The new structure is supported by cable and can handle 15,000 vehicles per day.

Work on the project also involved anchoring the bridge to allow it to withstand the highest wind speeds in the area.

The bridge is intended to make travelling easier across the river, lighten traffic on US 190 and improve travel from Alexandria to western Mississippi and beyond.