Train Protection and Warning System

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A TPWS transmission loop which, together with a second, forms the Overspeed Sensor System (OSS).

The Train Protection and Warning System (abbreviation: TPWS) is a train control system that is used on railway lines in Great Britain and Northern Ireland as well as in Australia . It was developed to close security gaps in the Automatic Warning System (AWS) .

Functions

TPWS comes in two forms that complement each other:

Overspeed Sensor System (OSS)
This is a speed test section about 200 to 400 meters before a danger zone ( main signal or slow speed zone ). In the middle of the track there are two antennas at a certain distance (between 4 and 36 meters) - the arming loop and the trigger loop . When the first antenna is passed, a time control begins to run on the locomotive. If the train reaches the second antenna too early - in less than about a second - it is too fast and an emergency brake is applied . The allowed speed can be adjusted by the distance between the two antennas.
Train Stop System (TSS)
At the location of the main signals, the two antennas are directly behind one another. If the signal shows "Halt", the train is automatically braked regardless of its speed.

The system is not fail-safe as it fails in the event of a power failure.

With regard to ETCS , TPWS is managed as a Class B system (Class B system). In Great Britain and Northern Ireland (but not in Australia) it is always used in conjunction with AWS. The Technical Specification for Interoperability therefore (see reference) leads AWS not separately, but rather look at it as an integral part of TPWS.

literature

  • Technical specification for interoperability (TSI) for the subsystem "train control, train protection and signaling" of the conventional trans-European rail system, Annex B
  • Rail Safety and Standards Board Limited (Eds.): AWS and TPWS Handbook . RS / 522 Issue December 3, 2015 (English, 28 pp., Rssb.co.uk [PDF; 1,2 MB ; accessed on April 17, 2017]).

Web links