Train Protection & Warning System
The Train Protection and Warning System (abbreviation: TPWS ) is a train control system which is used on railways in Great Britain and Northern Ireland and Australia. It is designed to close security holes in the Automatic Warning System ( AWS).
Functions
TPWS comes in two forms that complement each other:
- Overspeed Sensor System (OSS ): This is a Geschwindigkeitsprüfabschnitt about 200 to 400 meters of a danger ( main signal or speed restriction ). Centered in the track are located at a certain distance ( 4-36 meters ) two antennas - the arming loop and the trigger loop. When crossing the first antenna begins on the train for a time control to run. If the train the second antenna too early - in less than about one second - is reached, it is too fast, and there is an emergency brake. The permissible speed can be adjusted by the distance between the two antennas.
- Train Stop System (TSS): At the location of main signals, the two antennas are located directly behind each other. If the signal " stop" indicates the train is automatically braked regardless of its speed.
The system is not inherently safe because it fails during a power failure.
TPWS will regard ETCS out as a class B system. In Great Britain and Northern Ireland (but not in Australia), it always comes together with AWS for use. The Technical Specification for Interoperability ( see reference! ) Leads AWS therefore does not specifically, but look at it as an integral part of TPWS.