STEEL HAS triumphed over concrete in the battle to build key elements of the £200M landmark Millau Viaduct in south east France, it was confirmed last week.
Contractor Eiffage has decided that the main deck box girder and 90m high cable stay pylons above the piers will all be fabricated in steel.
The only concrete elements will be the giant 235m high piers below deck level, said Michel Virlogeux, one of the advisors to designers Foster & Partners/ EEG Sogelerg.
French prime minister Lionel Jospin gave the final go-ahead for the DBFO project last week.
The viaduct is one of the last missing links in the new A75 motorway which will eventually connect Paris to Barcelona (News last week. ).
Foster's original design had an unusual triangular cross section deck, with diamond cross section piers and pylons.
'But after the competition, wind tunnel tests led the triangular cross section to be changed to a more conventional trapezoid, ' said Virlogeux.
'This also features unusually wide hard shoulders at 3m, so that drivers from broken down UK trucks will be able to climb down from their cabs in safety.'
Foster also tweaked the pier design to create a more trapezoidal cross section below the point at which the pier splits into two arms.
The design team was required to produce steel and concrete alternatives for the pylons and the 350m span deck boxes.
Successful concessionaire Eiffage chose the steel option and plans to use incremental launching of the deck boxes using temporary intermediate supports.