RDS Products & Systems

Train Positioning System

[2] Video Train Positioning System

VTPS is a software-based technology pioneered by RDS that uses proprietary image processing of video feed to provide real-time, track-precise positioning information not readily available from any other system.

How does VTPS work?

A forward-facing camera is mounted in the windscreen of the train cab, and VTPS carries out real-time image processing of the camera’s video output to determine the following:

Positioning measurement How VTPS calculates it Benefits of VTPS


VTPS correlates one video frame with the next to determine the speed and distance moved

  • No wheel slip/slide compared with axle-end odometers


Each video frame is correlated with the next to determine track curvature from sideways motion

  • Determines direction taken through switch and crossings
  • Confirms train location by track matching


VTPS outputs a positive speed for forwards direction, negative for reverse

  • Improvement over speed sensors which provide absolute speed only


Image processing is used to identify tracks in the video feed

  • Identifies location of junctions and route taken
  • Provides confidence in track position by reporting on track to left and right

Sign reading

VTPS has the capability to detect and read machine- and human-readable signs, and to determine distance from them

  • Provides confirmation of position at a specific track location