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
Tarn (river) Tarn (river) The Tarn (, , possibly meaning 'rapid' or 'walled in') is a long river in southern France ("régions" Languedoc-Roussillon and Midi-Pyrénées), right tributary of the Garonne. The Tarn runs in a roughly westerly direction, from its source at an elevation of 1,550 m (5,085 ft) on Mont Lozère in the Cévennes mountains (part of the Massif Central), through the deep gorges and canyons of the Gorges du Tarn (that cuts through the Causse du Larzac), to Moissac in Tarn-et-Garonne, where it joins the Garonne downstream from the centre of town. Its basin covers approximately , and it has