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
Monocacy River bridge and viaduct painted some spans. <br> As of 2016, the bridge is in active rail service, operated by the Walkersville Southern RR. The original bridge was a "Bollman suspension truss". The Monocacy river bridge and viaduct structures were a mixture of wrought iron tension members and cast iron compression members, including other decorative elements, such as Doric styled vertical members and end towers, all cast iron and detailed. In 1872, Bollman's firm, Patapsco Bridge and Iron Works completed the bridge and viaducts with a total length of 326 feet. The ICC survey work papers indicate two rebuilds were performed on the Monocacy