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
Millau Viaduct World Wildlife Fund (WWF), "France Nature Environnement", the national federation of motorway users, and Environmental Action. Opponents advanced several arguments: Two weeks after the laying of the first stone on December 14, 2001, the workers started digging the deep shafts. There were four shafts per pylon; deep and in diameter, assuring the stability of the pylons. At the bottom of each pylon, a tread of in thickness was installed to reinforce the effect of the deep shafts. The of concrete necessary for the treads was poured at the same time. In March 2002, the pylons emerged from the ground. The