Monitoring Large Railways Infrastructures Using Hybrid Fbg/Raman Sensor Systems

In this paper we propose a hybrid fiber optics sensor system, based on space- and time-division multiplexed Fiber Bragg Grating (FBG) and Raman distributed temperature sensing (RDTS), for monitoring railway infrastructures. The main novelty consists in performing structural health monitoring by measuring the rail track geometrical conditions at important infrastructures like bridges. Installing FBG sensors and RDTS directly on the rail tracks at specific infrastructures allows a cost effective monitoring of their structural health by measuring the static strain and temperature spatial distributions. The geometrical rail track condition can be inferred in real-time and early warning provided if pre-defined geometrical thresholds are exceeded. The proposed technology has been validated in railway laboratories and in field trials where possible defects have been monitored in order to recommend train speed reduction or necessary train circulation block; the absence of false alarms have bee...