Vulnerability of bridge piers to general and local erosion of river bed

Bridges are large, quite complex, and expensive engineering structures, whose supports, i.e. piers in river beds, are exposed to a series of adverse influences, in particular to the impact of the erosion of a river bed. Disrupted stability of piers or their complete destruction leads to failure of bridge superstructures. We have been witnessing, particularly in recent years, the occurrence of large floods that damaged or even completely destroyed a large number of bridges. In this paper the main causes of general erosion and local erosion have been analysed, with a view toward the ways of determining the depth of local erosion, in order to meet the requirements of a correct selection of foundation depth of bridge piers and of undertaking the corresponding measures to prevent erosion.