Third Millennium BridgeZaragoza, Spain
The Third Millennium Bridge is the largest concrete bowstring arch built to date. It was constructed to close a ring road in the city of Zaragoza before the celebration of the BIE International Exposition of 2008. Thanks to its urban function and location in the city, on the one hand, and to the quality of its aesthetic and structural design, on the other, it has become an icon of the city and a worldwide engineering feat (it received a fib Award in 2010 and the Gustave Magnel medal among other recognitions). High strength, self-compacting white concrete was used in almost the entire bridge (C60/75 in the deck and C75/90 in the arch) to take slenderness to the limit. Complex erection procedures were needed for its construction, including the launching of a 34 m wide and up to 200,000 kN in weight deck, and the introduction of a 120,000 kN horizontal load in the crown of the arch using hydraulic jacks to put its final forces into play.