Largest double helix bridge

The largest and so far only double-helix structure bridge is the 280-m Helix Bridge in Singapore. Designed by Cox Architecture and Architects 61, with engineers Arup, it uses two intertwining steel helix structures to create a complex tubular truss. Fully opened on 18 July 2010 at a cost of SGD$82,900,000, the pedestrian bridge links Marina Centre with Marina South. If the steel were stretched out it would measure 2.25 km in length – but still uses five times less steel than a conventional box girder bridge.