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Publications
Automatic Train Protection for the rail network in Britain: A study
Executive Summary
Purpose of Study
This report was undertaken at
the request of the Deputy Prime Minister following
the railway accident at Ladbroke Grove. It examines
the consequences of signals passed at danger (SPADs)
and recommends ways to minimise their effects
including evaluating options for train protection.
It argues that although less than 1% of SPADs lead
to accidents they remain an area of serious concern
for railway safety. The SPAD phenomenon occurs in
other countries and on other railway systems.
However, comparative statistics are not available
owing to differences in signalling systems and data
collection. More research on human factors and
driver operation is strongly recommended but this
must be augmented by an urgent programme of fitting
enhanced forms of train protection.
Recommendation for the
Longer Term - ETCS
Looking at the long-term
solution of automatic train protection (ATP) this
report concludes that the system evolved by the
European Union called the European Railway Train
Management System/European Train Control System (ETCS)
is the best way ahead and likely to evolve into a
European Standard. ETCS is designed for operation at
three levels of sophistication. The most advanced
system (Level Three) also offers potential benefits
in the form of increased line capacity and more
rapid recovery from traffic disturbances. In the
longer run it is therefore likely to be fitted on
parts of the railway for commercial reasons with the
ATP features provided as a free side benefit.
Railway policy should therefore aim to move in this
direction which should be seen as the long-term
vision. However, ETCS is not yet fully developed,
though trials of ETCS (Level One) are already in
progress between Vienna and Budapest.
Recommendation for the
Immediate Future - TPWS
Using the criteria of
maximising safety by minimising the probability of
SPAD related accidents over the next 10 to 15 years,
this report concludes that the best solution
(irrespective of cost) is to fit the Train
Protection and Warning System. TPWS can be tailored
to address the areas of highest risk (mainly SPADs
associated with junctions) and has been specifically
designed for rapid fitment on both new and old
rolling stock. This enables it to offer a higher
level of overall safety up to 2008 compared with a
decision to go straight for the ETCS system. This is
in effect confirmation of the current plan of the
industry as defined in the 1999 Railway Safety
Regulations.
Enhancing TPWS in the Short
Term
However, TPWS does have
disadvantages. The most serious is that it will not
be fully effective for trains travelling above 75
mph. Studies have shown that in terms of avoiding
"ATP preventable accidents" it is about 70%
effective. Possible ways of reducing the effect of
this limitation are discussed and it is recommended
that a small pilot trial of a variant of TPWS called
TPWS+ should be set up. This variant could offer a
capability of extending its train protection
capability up to 100 mph, resulting in an improved
overall effectiveness of the system in the region of
75%. Further improvements can be achieved by the
complementary addition of enhanced emergency braking
on trains (this programme is currently under way),
defensive driving policies (also under way) and a
small change in traffic regulation rules at
junctions.
Upgrading TPWS to ETCS
A further disadvantage of TPWS
is that its technology is not compatible with that
needed to upgrade the system to the ETCS European
ATP system. As a possible way of avoiding this
problem, it is proposed that a second pilot trial
should be established to demonstrate a further
variation of TPWS called TPWS-E. This offers the
same functional performance as TPWS and TPWS+ but is
based upon the same technology as the European
systems. Therefore at the end of this trial it
should be possible to decide which mixture of
technology to take forward for TPWS installation and
whether it is feasible to operate with a mixed
system. Moving from a TPWS solution working with
about 70-75% effectiveness to the full European ATP
has the problem that it is more difficult to justify
the additional investment costs for a small marginal
improvement in safety. Here a TPWS-E solution helps
considerably since this reduces the cost and the
fitting time of the upgrade. An important
recommendation of this report is that all new
rolling stock should be provided with the wiring and
location spaces for the future European systems.
This small change to the cost of new stock would
offer a substantial reduction in fitting costs and
fitting times when the upgrading is introduced.
The Longer Term Development
of ETCS and the Need for Research
This report recommends a range
of research programmes (to be overseen by the
Strategic Rail Authority) which would enhance the
development and introduction of ATP. These include
evaluating the potential operational benefits of the
Level Three European Train Control System. If such
benefits are confirmed this should lead to
significant investments by train operating companies
in such systems providing a new, cheaper way of
increasing capacity. Plans should therefore be
developed for a suitable trial of a Level Three
system towards the end of this decade, giving the
opportunity of installing operational systems in the
next decade. There is reason to believe that the
installation and running costs of Level Three
systems will eventually become far cheaper than that
of all alternatives, due to their heavy dependence
on cellular radio technology and electronics (whose
costs continue to reduce) together with a reduced
dependence on trackside signalling equipment with
its associated problems of maintenance and risk to
trackside maintenance staff. This report also
touches on the problems of developing and testing
new systems such as ATP on the railway. Such trials
often impact upon the operational and financial
performances of different sections of the industry.
The current machinery for introducing new systems
(which is criticised by many parts of the industry
for its long time delays for establishing safety
cases and proving trials for new equipment) is
unable to give authority to an individual or a body
to oversee and operate such trials or fitting
programmes owing to multiple interfaces with
different organisations. Such problems are easy to
analyse though difficult to solve. Indeed, they may
be incompatible with the current franchise
agreements. However, it is important that the
Strategic Rail Authority and the Department of the
Environment, Transport and the Regions (DETR) give
some consideration to these issues if ATP and
improvements to train control systems are to be
taken forward in a cost effective and expedient
manner.
Sir David Davies CBE FREng FRS
President
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