Field test for real-time position and speed monitoring of trains using phase-sensitive optical time domain reflectometry (Φ-OTDR)

It is essential to carry out real-time position and speed of trains to ensure the safety of railway operation. In this paper, the phase-sensitive optical-time-domain reflectometry (Phi-OTDR) is proposed and demonstrated to overcome the disadvantage of the track circuit that is currently used and has the risk to be damaged by lightening, for the first time, to the best of our knowledge. A long sensing cable, buried nearby two parallel railways, is used to detect the vibration signals generated by trains with Phi-OTDR and the real vibration signals of the trains are extracted/quantified utilizing wavelet denoising. With the wavelet edge detection, the operation status of two nearby trains, including their relative position and speed, are obtained over a 10.2 km measurement length in real-time. This work offers a new passive way for safety monitoring of railway operation.