Royal Academy of Engineering : 22 February 2000
Safety First means TPWS then ATP says Sir David Davies
The best way to minimise the likelihood of accidents (and save lives) on Britain’s railways during the next 10
years is to fit the Train Protection and Warning System (TPWS) to those railway junctions most at risk, says Sir David Davies, President of The Royal Academy of Engineering, in his report to the
Deputy Prime Minister Automatic Train Protection for the Railway Network in Britain: a Study published on 22 February 2000.
Sir David’s recommendation is based on the fact that TPWS, which is fully tested and ready for implementation by Railtrack, will prevent
70 per cent of accidents due to signals passed at danger (SPADs) by 2004 based on the current accelerated fitting programme. The more expensive alternative, a full automatic train protection (ATP)
system, would take at least 10 years to provide the same safety level because it would take much longer to install.
The argument is not based on financial considerations, but on the potential safety gain.
Long-term, Sir David recommends that the UK rail industry starts planning immediately to fit the most advanced ATP system available to the bulk
of the rail network. This should be the European Train Control System (ETCS), of which there are three different levels, the most sophisticated of which offers considerable benefits of increased line
capacity and recovery from delays. ETCS has already been adopted as the European Standard for the European High Speed Network through EC Directive 96/48/EC. However, Sir David’s preferred
option – the most advanced ETCS Level Three is still in development.
Basic TPWS will stop a train travelling at up to 75 mph towards a red light. Critics note that it cannot guarantee stopping a train travelling
at higher speeds so Sir David recommends urgent trials of an enhancement, TPWS+, designed to be effective at up to 100 mph. The great advantage of both these systems is that they have been designed
specifically to fit existing rolling stock in order to speed up their implementation. However, as they are both analogue systems, they are incompatible with upgrade to the digital ETCS. Sir David
therefore also recommends evaluation of a TPWS variant called TPWS-E, which should be just as quick to install on our existing track and trains but could be upgraded to ETCS in due course.
"Fitting ETCS on new lines like the Heathrow Express and the Channel Tunnel Rail Link is not a great problem," says Sir David. "The more
difficult challenge is in retro-fitting complex equipment to ageing rolling stock." He recommends that all new trains should incorporate the appropriate wiring, location space and radio communication
equipment ready for ETCS by 2003, and that all new signalling systems from now on should examine the option of making them ETCS-compatible.
"I am a little uneasy about an interim system (TPWS) which does not lead to the long-term solution (ETCS), but I still believe it is the right
direction in which to move," says Sir David. "The operational advantages of ETCS Level Three – increased capacity and faster recovery from delays – will make it very attractive to train
operating companies in the next decade: it may even pay for itself."
Sir David recommends that existing plans to fit ETCS to the UK’s high-speed lines under the EC Directive should continue as soon as
possible. Work on the West Coast Main Line upgrade is planned to start in 2002 and he wants to see the start date for the East Coast Main Line brought forward to 2006. He also suggests that the 110
mph Midland Main Line should be considered for ETCS, even though it is not part of the European High Speed Network.
How these developments can be taken forward in a rail industry fragmented after privatisation worries Sir David. "The current machinery for
introducing new systems is unable to give authority to an individual or a body to oversee the implementation, owing to multiple interfaces between the different organisations," he says. "The
Department of the Environment, Transport ∓ the Regions and the Strategic Rail Authority should examine this carefully."
Despite this, Sir David is keen to see his recommendations taken forward urgently, such as the trials of TPWS+ and TPWS-E, as a delay could
lose the opportunity to make the TPWS installation programme more effective. "I hope that the railway industry, with the encouragement of the Strategic Rail Authority, would be prepared to progress
such work – even if the Government felt bound to await the report of the joint inquiry by Lord Cullen and Professor John Uff into SPADs and ATP," he says.
Source: Royal Academy of Engineering
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