Real-Time Monitoring of Railway Traffic Using Fiber Bragg Grating Sensors

In this work, we present field tests concerning the application of fiber Bragg grating (FBG) sensors for the monitoring of railway traffic. The test campaigns are performed on the Spanish high-speed line Madrid–Barcelona, with different types of trains (S-102 TALGO-BOMBARDIER, S-103 SIEMENS-VELARO, and S-120 CAF). We located the FBG sensors in the rail track at 70 km from Madrid in the country side, where the trains primarily are tested during commercial operation with maximum speeds between 250–300 km/h. The FBG sensor interrogation system used allows the simultaneous monitoring of four FBG sensors at 8000 samples/s. The different position of the FBG sensors in relation with the rail can be used for different purposes such as train identification, axle counting, speed and acceleration detection, wheel imperfections monitoring, and dynamic load calculation.