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
Michel Virlogeux Large Concrete Bridge Division, and in 1987 of the large Bridge Division, Steel and Concrete. During twenty years he designed more than 100 bridges, including the Normandy Bridge which held the world record for longest cable-stayed bridge for four years. In 1995 he left the French Administration and set up as independent consulting engineer; his major achievements include his participation in the construction of the 'Second Tagus Crossing', the Vasco da Gama Bridge in Lisbon, and the design of the Millau Viaduct in France. Several of his bridges have received architectural awards. Since 1977 Dr Virlogeux has been a part-time