The viaduct IX crosses the valley at a maximum height of 80m. It comprises two parallel, continuous bridge decks, one of which is 486m long and the other 456m.
The decks are composite, with steel beams and prefabricated reinforced concrete slabs. The construction method used was the incremental launching one.
The piers have a maximum height of 75m with hollow octagonal constant cross-section shafts and column heads on top. The foundations are direct on granite and schist formations.
Construction completed in 2005.