Its not that It wasnt Necessary! Read this.
Before the bridge was constructed, traffic had to descend into the
Tarn River valley and pass along the
route nationale N9 near the town of Millau, causing heavy congestion at the beginning and end of the July and August vacation season. The bridge now traverses the Tarn valley above its lowest point, linking the
Causse du Larzac to the Causse Rouge, and is inside the perimeter of the Grands Causses regional natural park. The bridge forms the last link of the
A75 autoroute, (
la Méridienne) from
Clermont-Ferrand to
Pézenas (to be extended to
Béziers by 2010). The A75, with the A10 and A71, provides a continuous high-speed route south from
Paris through
Clermont-Ferrand to the
Languedoc region and through to
Spain, considerably reducing the cost of vehicle traffic travelling along this route. Many tourists heading to southern
France and
Spain follow this route because it is direct and without
tolls for the 340 kilometres (210 mi) between Clermont-Ferrand and Pézenas, except for the bridge itself.