AUTOMATIC TRAIN PROTECTION

(Redirected from Automatic train protection)

'Automatic Train Protection (ATP)' in Great Britain refers to either of two implementations of a train protection system installed in some trains in order to help prevent collisions through a driver's failure to observe a signal or speed restriction. Note that ATP can also refer to automatic train protection systems in general, as implemented in other parts of Europe and elsewhere.

Contents
Overview
Continuous and intermittent ATP
Eurobalise
Accidents and ATP
Accidents preventable by ATP
Accidents not preventable by ATP
Accidents reducable by ATP
See also

Overview


This system uses a target speed indication and audible warnings to warn the train driver if they are likely to exceed a speed profile that will cause the train to pass a red signal or exceed a speed restriction. The system will apply the brakes if the driver fails to respond to these warnings. The system takes into account the speed and position of the train relative to the end of its 'movement authority' in issuing the warnings and applying the brakes.
By the 1980s microprocessors had developed sufficiently for BR to carry out pilot trials on existing European ‘off the shelf’ ATP – fitting part of the Great Western Main line with the TBL1 system from ACEC and the Chiltern Main Line route with SELCAB a derivative of the German LZB system from Alcatel and GEC.
In the early 1990s, following the Clapham Junction rail crash in December 1988, and two other fatal accidents in early 1989 caused by SPADs, British Rail was keen to implement the ATP system across the entire British railway system. However, the cost (estimated at over £1bn) was baulked at by the Conservative government, who were preparing the company for privatisation.
All First Great Western's High Speed Trains (HSTs) are now fitted with ATP, and are not allowed to carry passengers unless the system is functioning. This requirement is in response to the Ladbroke Grove rail crash.
ATP is given permitted speed and location information from the track via encoded balise(s), encoded track circuit or more recently via radio.

Continuous and intermittent ATP


ATP systems may be broadly grouped as continuous and intermittent. With continuous ATP, a cable is laid between the rails for the full length of the block section. The rails themselves may also be used as the cable whereby the track talks to the train. With intermittent ATP, beacons called balises are mounted between the rails on the approach to signals, and perhaps a few other locations.
The Eurobalise is an attempt to set a standard for ATP across Europe where balises and on train equipement made by any manufacturer work together with each other.

Eurobalise


Eurobalise is the common specification for an ATP system able to go anywhere, and overcome the multiplicity of non-compatible designs currently in use. The balises and the train board equipment can be made by any manufacturer.

Accidents and ATP


Accidents preventable by ATP


Salisbury rail crash - 1906 - Overspeed through sharp curve through station. 28 killed.

Morpeth rail crashes - 1969 etc. - Overspeed through sharp curve.

Malbone Street Wreck - 1918 - too fast around sharp curve - 93 killed

Harmelen train disaster - 1962 - SPAD in fog causes collison - 91 killed.

Violet Town railway disaster - 1969 - collapsed driver overruns crossing loop and collides with opposing train. 9 killed.

Glenbrook train disaster - 1999 - too fast after Stop and Proceed.

Waterfall train disaster - 2003 - too fast around very sharp curve.

Ladbroke Grove rail crash - 1999 - inexperienced driver misread complicated signals, passes red signal and causes head on collision.

Hines Hill train collision - 1996 - driver misjudges end of crossing loop during simultaneous cross with opposing train. 2 killed.

Seven Hills, Blacktown and Concord West - drivers take turnouts at too high a speed, causing minor injuries to passengers.

Amagasaki rail crash - 2005 - Overspeed through sharp curve. 107 killed, 555 injured.
Accidents not preventable by ATP


Clapham Junction rail crash - 1988 - wrong-side failure - both signal and balise would have shown false green light.

Cowan rail crash - 1990 - wrong-side failure - caused by sand on the rails.
Accidents reducable by ATP


★ In the Gare de Lyon train accident in Paris in 1988, a brake failure was the prime cause of the accident. However a more modern ATP system, if fitted, might have reduced the intensity of the collision in two ways:


★ Firstly, the on board ATP equipment may have noticed the excessive speed of the train sooner than the driver.


★ Secondly, the ATP system presumably would have applied a secondary backup brake system, even though this might have "risked" flat wheels. Apparently, the driver failed or forgot to apply that secondary brake.

See also



Automatic Warning System

Train Protection & Warning System

Train protection system

Automatische treinbeïnvloeding (ATB) – a Dutch system which would have prevented the Harmelen train disaster.

List of rail accidents

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