Signal failures

It may be the accident prevention solution for the UK’s railways, but, as Rob Coppinger reports, Automatic Train Protection is facing long delays.

The Southall and Ladbroke Grove train disasters were a chilling reminder of the potential danger lurking on the UK’s railways of trains passing a red, or ‘danger’ signal.

Following the 1999 Ladbroke Grove crash in which 31 people died, deputy prime minister John Prescott promised to find the money for Automatic Train Protection, a system that would prevent such accidents. Last year the Cullen-Uff inquiry into the two disasters recommended a timetable for installing it by 2010.

But a year later already it is clear this timetable will not be met, and that the government is backtracking amid concerns about the cost. Instead, it seems that rail safety will rely on the cheaper, but less effective, Train Protection and Warning System.

ATP, defined as a system that continuously monitors the speed of a train and applies the brakes automatically if an unsafe situation develops, is in full operation on just two lines in the UK: Chiltern and the newly-built Heathrow Express link. It has been fitted on a third, the Great Western main line from Paddington to Bristol Temple Meads, but after 10 years of trials it is still only 80 per cent operational. If fully operational, it could have helped to prevent both the Southall and Ladbroke Grove disasters. ATP also operates on Eurostar trains in France and in the Channel Tunnel – but not in the UK.

British Rail’s research arm began investigating ATP systems in the 1960s. Not until 1989, after crashes at Purley, Surrey, and Bellegrove Junction, however, did it commit itself to installing the system. It began in 1991 with trials on the Chiltern line and the Great Western main line, before the government decided in 1995 to abandon plans for installation nationwide on the grounds of cost.

The Ladbroke Grove crash happened before Professor John Uff’s official inquiry into the Southall crash – two years earlier on the same line – had had time to report. After the second disaster, Sir David Davies, an eminent electrical engineer and then president of the Royal Academy of Engineering, was appointed by Prescott to produce the definitive study on train protection in the UK. This formed the basis of the technical content of the joint report into Southall and Ladbroke Grove by Uff and Lord Cullen.

Davies said that though all possible methods of preventing trains passing red signals should be investigated, ‘drivers are already operating very near to the likely limits of human performance for a highly repetitive safety function’, which pointed to the need for train protection.

He recommended the joint European version of ATP, the European Rail Traffic Management System, as the best way forward. Of the three forms of this, level three, the most complex, is still under development. Davies recommended ERTMS should be fitted to all lines where trains operate at 100mph or more. This could start in 2003 and would take nine years.

In the short term, he said, the Train Protection and Warning System should be implemented by 2003. TPWS does not monitor speed continuously, but uses speed traps at critical signals. It was specifically designed to be fitted to new and old rolling stock and would offer a higher level of overall safety until 2008 compared with going straight for ERTMS.

Davies thought that ERTMS level three should be the ultimate goal, pointing out that unlike the other versions, it offered potential commercial benefits such as increased line capacity. He also predicted it would ultimately be cheaper than all other systems.But little progress has been made towards installing ERTMS. A version is being tested by an Alstom-Railtrack team of engineers at the Alstom Midlands Test Centre, Leicestershire. The technology is to be implemented on the West Coast main line, which runs Virgin high-speed trains.

So far, the ERTMS project has conducted tests using level one technology to bring refitted trains to an automatic stop from 30mph. This was carried out just before Christmas, and tests are continuing. Level two trials will take place in 2003.

Railtrack, Alstom and Virgin all claim the tests are on schedule and introduction of ERTMS on the West Coast main line will happen by the target date of 2005. From London to Crewe – because trains travel more quickly – the line will use level two technology, while the Crewe to Scotland section will have level one.

But that is the only firm date for its installation anywhere on the network. After 2005, no rail organisation or government department has any budgeted plans for widespread implementation.

Moreover, neither the government’s 10-year transport plan nor the Strategic Rail Authority’s Strategic Plan for the coming decade, published in January, refer to any budget for ERTMS implementation.

Even Sir David Davies – now chairman of Railway Safety, the Railtrack Group’s safety arm set up as a not-for-profit subsidiary after the Hatfield crash in 2000 – confirms his belief that the Cullen-Uff timetable for the introduction of ATP systems will not be met. ‘It’s no longer feasible,’ says Davies, the first senior rail expert to admit as much publicly.

He recognises there are other major problems with the UK implementing the European safety system, notably integrating the infrastructure on old track and rolling stock.

That obstacle will remain well beyond 2005. But despite difficulties of integrating new trackside systems with old technology, as required in ERTMS levels one and two, the rail industry is not even expected to opt for level three – the purely radio-based version of ERTMS which would take over the entire signalling function.

Industry expectations are pre-empted a report from the ERTMS Programme Team, also known as EPT, which will be produced next month. This team was set up by the SRA and Railway Safety in April 2001 to analyse the different levels of ERTMS and the technologies and capabilities of each variant of each level. Its conclusions will contribute to the final government decision the government on what system the UK rail network gets and how it is implemented.

But it has already been decided that the West Cost main line upgrade will use, at most, level two. That decision, according to a spokeswomen for the ERTMS trials at Old Dalby, was taken three-and-a-half years ago. And Davies now agrees it is unlikely that anything other than levels one or two will ever be used in the UK.Whether the Old Dalby trials next year or the EPT report approves this new level two or not, the potential cost of APT will remain an obstacle.

The Cullen-Uff report did not give an exact cost for ERTMS installation. It said: ‘There is little hard evidence of the likely cost. Railtrack has suggested that the indicative cost of fitting all routes with a line sped of 75mph or more would be £1.9bn, but the true figure will remain uncertain for some considerable time.’

Despite media claims of the government balking as estimates of the cost of ATP installation escalate to £3bn or more, Davies believes the picture is still unclear. ‘No one knows the cost of something as complicated until you have a working system installed somewhere.’

The first working ERTMS system, assuming the West Coast main line trials are completed on schedule, will not exist until 2005. If the decision about rolling out the system more widely is delayed until that date, then UK-wide installation of the system cannot be finished until 2014 at the very earliest.

For the forseeable future, then, most passengers will have to travel on trains using a safety technology which is estimated will only be 70 per cent effective at preventing accidents caused by signals passed at danger.

The Train Protection and Warning System is currently being installed across the network. It uses simple speed traps set at distances of 350m from red signals to apply emergency brakes automatically if a train passes at too high a speed.Under existing safety regulations, TPWS must be implemented across the entire UK network by 1 January 2004. According to Railtrack and the train operating companies, the project is currently on schedule. Trackside equipment and rolling stock modification are under way.

Changes to some trains are necessary because they must be able to achieve 12 per cent g deceleration under braking. Old rolling stock travelling up to 75mph – which could not achieve this – would pass straight through red signals and the ‘stopping safety zone’ following the signal.

Of all the train operating companies, Thameslink is one that has fully fitted TPWS already. This system has been operational since June last year and now the company is considering fitting ERTMS. It is believed that TPWS has already helped trains to avoid accidents.

As Sir David Davies says: ‘There have been quite a few instances of trains being braked to rest using the TPWS system. You can never prove there would have been an accident. In one or two of them it looks very clearly as if there might have been. But you can’t prove it.’

However, the question still remains: how many more accidents could have been prevented by ATP?

Promises, promises: The timetable proposed by the Cullen-Uff inquiry

2006: Trackside ERTMS on the East Coast main line (brought forward from 2012)

2006: Full ATP on the Great Western main line

2007: Trackside ERTMS on West Coast main line to current timetable

2008: ERTMS on all lines with trains travelling at more than 100mph

2010: No train can travel at over 100mph unless fitted with ERTMS or other protection

All routes with a line speed of 75mph-100mph to be risk-assessed to establish priority for fitting ATP

All new trains to be ‘ERTMS ready’ (i.e. fitted with relevant equipment as far as possible)

What the various systems offer

Automatic Train Protection

A system which continuously monitors train speed, takes account of signalling information and applies the brakes if an unsafe situation arises.


BR undertook to install ATP after the 1989 Clapham disaster, and a trial programme began of two different systems in 1991: one on the Great Western main line between Paddington and Bristol, which is still only 80 per cent operational, and the other on the Chiltern line. BR encountered numerous teething troubles related to fitting the systems to old rolling stock. A similar system to that on GWR has been operational on the Heathrow Express line from new. Plans to install nationally were abandoned by the Conservatives in 1995.

European Rail Traffic Management System

The ERTMS has been many years in development, with the EC working with member state governments, rail authorities and industry to enable high-speed train systems in mainland Europe to work together. There are three levels of ERTMS technology.

Level one

An ATP system overlaid on a conventional fixed block signalling system, similar to that on GWR. It uses trackside transponders called Eurobalise for transmitting trackside data and signal information to trains.

Level two

A fixed-block system which uses a radio communications system across the track network including tunnels to control all train movement and provides the information on movement authority and speed without using the lineside signals, which are no longer needed if all trains are fitted with ATP.

Level three

This level performs the whole signalling and train control operation over a digital GSM-R radio network to determine position and speed. Also allows ‘moving block’ operation in which trains are separated by their safe braking distance. Allows trains to travel closer together, unlocking extra capacity on the network, and is quicker to recover from disruption.

Train Protection and Warning System (TPWS)

Developed as a cheaper way than ATP of reducing accidents caused by trains passing red signals. TPWS combines a train stop system with a speed trap. It is triggered at speeds of over 40mph and is designed to stop a train travelling at 75mph within the overlap region.


Involves the addition of extra speed traps further back from the signal. These can be up to 1.5km for a train travelling at 125mph.


Involves the use of trackside transponders linked to train and track control, as well as speed traps, to monitor train movement. It is said to be potentially compatible with ERTMS technology.