Real-Time Position and Speed Monitoring of Trains Using Phase-Sensitive OTDR

TLDR

It is essential to carry out real‑time position and speed monitoring of trains to ensure railway safety. The study demonstrates phase‑sensitive OTDR to overcome the drawbacks of conventional track circuits, which are vulnerable to lightning damage. A long buried sensing cable adjacent to two parallel railways records train‑generated vibration signals with Φ‑OTDR, and wavelet denoising extracts real‑time vibration data. The system obtains real‑time relative position and speed of two trains over a 10.2‑km stretch, demonstrating a new passive safety‑monitoring approach.

Abstract

It is essential to carry out real-time position and speed monitoring of trains to ensure the safety of railway operation. In this letter, the phase-sensitive optical-time-domain reflectometry (Φ-OTDR) is demonstrated to overcome the drawbacks of the track circuit, which is widely used and has the risk to be damaged by lightening, for the first time. A long sensing cable, buried nearby to two parallel railways, is used to detect the vibration signals generated by trains with Φ-OTDR and the real-time vibration signals of the trains are extracted/quantified by wavelet denoising. With the edge detection by normalized sliding variance, 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 letter offers a new passive way for safety monitoring of railway operation.