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
Orthotropic deck in the US are in California, including the San Mateo-Hayward Bridge, which is one of the first major bridges in the US to be built using an orthotropic deck. Some very large cable-supported bridges, plus current record span (cable-stayed bridges and suspension bridges) would not be feasible without steel orthotropic decks. The longest or record span box girder, slant-leg bridges; arch bridges; movable bridges and two Norwegian floating bridges all use orthotropic decks. The Millau Viaduct a cable-stayed bridge of Millau, France has the largest orthotropic steel deck area of any single bridge. The lower total gross weight of the