Railtrack has admitted that the reliability of the Automatic Train Protection system that was fitted on the Southall train that crashed last Friday, could have been affected because it was retrofitted.
‘The problem with ATP is that it is a bolt-on,’ said a spokeswoman. ‘We’ve got to get it to integrate with the signalling system. That’s where the reliability is. The inquiry will take that factor into account.’
Up to 34% of Great Western’s trains carry ATP on a trial basis. It has not been officially stated whether the system installed on the crashed train was switched off or if it failed under use.
ATP has been tried out on the Bristol-London and Chiltern lines. Its use was recommended after the 1988 Clapham rail disaster.
But despite years of development, the Government decided two years ago that ATP was too expensive to use across the whole network. Upgrading the 30-year-old infrastructure it has to work with would cost nearly £1bn.
Resources have instead been devoted to the trains themselves to make them more crash resistant. Industry and Government resources have been devoted to phasing out ‘slam door’ trains, and replacing them with modern slide-door carriages which are more robust.
Railtrack is now expected to come under pressure to develop its Train Protection Warning System, a hybrid of ATP and the less sophisticated Advanced Warning System, which applies the train’s brakes if its driver goes through a red light.
AWS stops the train only 50m before the next signal, which could be too late to prevent an accident.
Contracts to manufacture the hybrid system have not yet been placed.
An integrated version of ATP is expected to come into operation on the West Coast Main Line by 2010 when it will be designed as part of a new signalling system, known as transmission-based signalling.