A Smart System Based on Wireless Sensors for Vibration Monitoring of Railway Bridges

In recent years, the degradation over time of bridges put the focus on the structural health monitoring of such infrastructures. The continuous vibration monitoring of these structures presents two main advantages. The first one is the prediction of the degraded condition by means of suitable algorithms and the second one is related to the possibility of receiving real time alarms if some thresholds are exceeded. Nevertheless, the use of traditional wired monitoring systems is still limited by high cost related to both the instrumentation and the system installation on the structure. Moreover, the wires maintenance and the time required for data processing represent two significant constraints. In this paper, a feasible solution to these problems is presented. An innovative monitoring system, based on a network of wireless sensors managed by a gateway, has been designed. The wireless sensor nodes have been developed by adopting low-power and low-cost electronic components. Such sensors can acquire vibration data and perform pre-processing operations on board. Moreover, these devices can operate for a long time through the adoption of energy harvesting techniques for the battery recharge. The developed system has been installed for a long-term field test on a railway bridge, in parallel to traditional wired accelerometers. Many significant data have been collected and analysed to assess the performance of the system. The validation of this approach will allow to install these devices in an easy and cheap way on many infrastructures, with the goal to get synthetic structural health indicators in real time.