In-field assessment of bridge pier scour by means of Fiber Bragg Gratings: System and algorithms

• Effective algorithms for estimating river bed level at bridge piers with fiber optics. • A strategy to overcome monitoring system failure is validated. • Rare real data are presented and used for monitoring strategy validation. BLESS (Bed LEvel Seeking System) is a sedimeter that measures riverbed level around bridge pier in water. It is based on Fiber Bragg Gratings and the working principle is based on the measurement of the different heat dissipation behaviour in the saturated soil compared to the flowing water. It is an innovative part of a complex monitoring system installed on a road bridge over the Po river (Italy). After two years of data storage, a comparison of two different methods to detect the riverbed level can be performed. One of them showed results in satisfactory agreement with those provided by a traditional reference device, i.e., an echo sounder. Furthermore, coupling the two different proposed bed level estimation methods allows deriving significant information about the health status of the sedimeter. The device is reliable enough to operate and survive in very harsh environments and it is ready for further engineering applications.