SmartRail: A System for the Continuous Monitoring of the Track Geometry Based on Embedded Arrays of Fiber Optic Sensors

In this work, we propose the concept of the Smart Rail, an innovative system for the continuous monitoring of the track geometry based on embedded arrays of Fiber Bragg Grating sensors and Raman-based distributed temperature sensors. First, we discuss how our technology design, based on a custom metallic patch embedding the FBG sensors and brazed on the track, overcomes the robustness concerns of the State of the Art. The metrological principle is formulated based on an analytical/FE model allowing the correlation of the measured signals to the local curvature deformation of the rail, and then to reconstruct the global track geometry. The effect of spatial sampling on the detection of even short-wave defects is addressed through simulations, as being a crucial trade-off between effectiveness and complexity. Experimental results performed on a first prototype demonstrate an efficient strain transfer with excellent agreement with the theoretical predictions. Hence the proposed technology seems very promising for the next generation of monitoring systems, in terms of robustness and compatibility with maintenance operations.