Millau Viaduct slightest movement in the Viaduct, and measure its resistance to wear-and-tear over time. Anemometers, accelerometers, inclinometers, temperature sensors are all used for the instrumentation network. Twelve fibre optic extensometers were installed in the base of pylon P2. Being the tallest of all, it is therefore under the most intense stress. These sensors detect movements on the order of a micrometre. Other extensometers, electrical this time, are distributed on top of P2 and P7. This apparatus is capable of taking up to 100 readings per second. In high winds, they continuously monitor the reactions of the Viaduct to extreme conditions. Accelerometers
Route nationale 9 "Parc Natural Régional des Grandes Causses". After crossing the "Col d'Engayresque" (888 m) the RN 9 re-appears and drops into the Gorges du Tarn and onto Millau where the road crosses the river and climbs up to the "Causse du Larzac" offering views of the valley and viaduct. The RN 9 provides a trunk road route avoiding the toll on the Autoroute A 75 as it crosses the valley on the Viaduc de Millau. The RN 9 has again been replaced by the A 75 for this section. At the "Pas de l'Escalette" just South of Le Caylar Roches the