Acoustic Sensing - A train’s vibration pattern as it progresses its journey is picked up by lineside sensing equipment, usually a fiber optic cable. The resultant change in optical patterns will constantly detect a train’s presence and speed….Detecting rock falls was an initial application, but, since then, the technology has been developed to provide a means of detecting trains. An injected light source on to a dark fiber will see a marginal change in the refractive index where any disturbance takes place. The time taken for this ‘back scatter’ to get back to the source enables the distance to be calculated.
The processing by a tracking algorithm has advanced to enable more intelligence to be obtained from the reflected pulses, according to Kevin Tribble from Sensonic, and the latest systems are capable of measuring both train location and speed with interfaces to traffic management systems and customer information systems. Installations exist worldwide, including on Network Rail and London Underground.
Train Location Systems
Rail Engineer April 3, 2020