Scour at river bridge piers: real-time vulnerability assessment through the continuous monitoring of a bridge over the river Po, Italy

Bridge failures are not uncommon during floods. Therefore, the assessment of bridge vulnerability is crucial to help a bridge's administration take the best decisions during emergencies (i.e. closing the bridge). The first step to achieve this is to implement a monitoring system providing needed information to develop scenarios based on administration response time. The proposed system seeks a real-time evaluation of the loads acting on the bridge. Wind and water contributions, debris accumulation upstream of piers and river bed level are evaluated by specific devices. The most difficult measurement is the identification of the riverbed position in close proximity to piers. Scour model predictions are still far from robust and accurate and no standard devices are available to measure it. Unfortunately, the main reason for bridge failure is scour around bridge piers, called local scour. A monitoring system was developed for this purpose and installed on a critical bridge over the river Po in Italy, as a result of the cooperation between the Politecnico di Milano and the Province of Mantova. The aim was to measure the main parameters for a proper evaluation of the bridge's vulnerability. The paper's focus is twofold: to show long-term data and all the phases needed to assess bridge safety. The first aspect, not so common in the literature, is useful to understand the temporal evolution of the environment around the bridge. The second one provides a roadmap for risk assessment and management decisions relying on the widely available database. With regard to this second topic, another paper describing the overall strategy has already been published. The main focus here is on potential implementation, with an emphasis on the available data.