Train Protection Warning System
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The Train Protection & Warning System (TPWS) has been deployed across the entire UK railway network. Its purpose is to safely stop trains that pass signals at danger so as to avoid a collision. It is used across the country except in places where Automatic train protection (ATP) is installed.
Unlike ATP, it does not aim to stop trains at or before a signal that is set to danger. It aims to stop the train in the overlap area beyond the signal. The overlap is the margin of safety that is always left between trains. According to the UK's Health and Safety Executive, TPWS is estimated to prevent between 65% and 80% of fatalities that would be stopped by a full ATP system.
TPWS is an interim measure until a full ATP system is installed across the country. The major problem with TPWS is that it is only fully effective up to a speed of 75mph (120km/h). An uprated version of TPWS called TPWS+ is being planned that will be effective up to 100mph (160km/h) and will be deployed in around 400 high risk places around the country.
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Limitations
TPWS has no ability to regulate speed after a train passes a signal at stop in accordance with Stop and Proceed rules.
Thus TPWS would not help prevent the following accidents
In use by
The TPWS system is used in
- Great Britain with AWS magnets, and short overlaps
- Victoria, Australia albeit without any AWS magnets, but with full length overlaps.
List of accidents preventable by TPWS
- Purley Station rail crash of 1989, 5 killed
- Invergowrie rail crash of 1979, 5 killed
External links
- Health & Safety Executive Train Protection Information (http://www.hse.gov.uk/railways/liveissues/tps.htm)