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ERTMS in the UK another perception


There continue to be divergent views on how effective ERTMS – the European Rail Traffic Management System – will be in a) resolving the problem of capacity constraints, b) creating a safer railway, c) reducing the cost of signalling and d) making the train service more reliable.

Rail Engineer has reported on those views before. Andrew Simmons of Network Rail (issue 120, October 2014) and Ian Maxwell of the Office of Rail and Road (ORR) (issue 131, September 2015) have both outlined their hopes for ERTMS, and expressed their concerns. Opinions differed widely, ranging from the Network Rail message that it will achieve all the above goals, through to the difficult logistics of fleet fitting from the train operators and a very cautionary view from the ORR who were distinctly nervous about the cost and timescale needed to roll the system out as well as whether it can deliver what is claimed.

Now, in advance of a conference on the topic to be held in London on 22/23 March, Rail Engineer has met with one of the event’s speakers. Tom Lee, the professional head of CCS and deputy director of research and standards, gave an insight on what the RSSB is thinking.

A general perception

The technology (principally the ETCS Level 2 equipment) has matured and is now considered reliable. It benefits from being a common European system and is a key part of the rail strategy for the next 15-20 years. A worry is the continuance of change requests, often triggered by the need to suit local operating preferences, since these cause unnecessary distractions and put at risk the whole concept of interoperable working.

Claims that ERTMS/ETCS (European Train Control System) can dramatically increase capacity need to be considered carefully. They are valid to a degree, since ETCS does away with the constraint of traditional physical signals and the spacing of these to suit the worst performing train on the route. If considering only plain line sections of a main line railway, then up to a 40 per cent increase in throughput is possible. However, a railway is seldom like that and the impact of stations and junctions will always limit the capacity improvement gained only by the signalling system. In reality, ETCS alone is unlikely to deliver significant capacity increases but it does reduce one constraint.

Nonetheless, RSSB would like to see a speed up of the rollout programme as improved safety will result from the full ATP provision that comes with the package as well as being a replacement for TPWS, which is an ageing technology. Deployment of ETCS is also consistent with the Rail Technical Strategy.

Approval of usage

Although RSSB has no formal role in the safety sign off for ERTMS, it does give advice to Network Rail and the train operators when questions are asked. The advantage of ERTMS being a European system is the opportunity for cross acceptance. If a balise works successfully in Holland or Spain then, providing it is deployed in accordance with the specifications in the UK, there is no need for any further safety approval before it is placed into service.

Similarly, once the fitting of ETCS equipment into a particular class of rolling stock, such as the Siemens Desiro City train for Thameslink, is approved, no need exists to instigate a lengthy approval process as later marques of the stock are built. RSSB is involved with Virgin for the operation of the ECML fleet, with Hitachi for the IEPs (Class 800/801), with Govia for the new Thameslink Class 700 units and with Crossrail for the forthcoming Class 345 trains.

A particular challenge at the moment is the operation of Crossrail trains to Heathrow Airport. This section of line is fitted with the Great Western ATP system (installed as one of two pilots by BR) and there is no desire to equip the Class 345 trains with this system as they will already be fitted with ETCS, TPWS and AWS.

Because GWML ETCS deployment is likely to be delayed beyond the time Crossrail starts operation, the route will be equipped with an enhanced TPWS system out to Airport Junction but an ATP is required on the Heathrow branch to maintain the same level of safety on that section. The result means the branch must be equipped with ETCS, resulting in the challenge of changeover from one system to the other at speed. RSSB is undertaking research on signalling transitions to inform on the design and operation for such occurrences.

The legal responsibility for negotiating ERTMS deployment approvals is with the project team that is designing and constructing the system in conjunction with the National Supervisory Authority, which in the UK is the ORR.

The Digital Railway

The ERTMS programme is being taken forward by Network Rail’s Digital Railway team, and the principles for doing this are good in that it separates the project from the day job of running the railway. The RSSB view is that the separation may need to become even more distinct from Network Rail so as not to get entangled with the day-to-day rules and organisational structure. A cross industry team to consider all aspects of ERTMS deployment is the best way forward for the Digital Railway people to achieve maximum consensus.

Heavily linked with ETCS are TMS (Traffic Management Systems) and DAS (Driver Advisory Systems). Maximising capacity improvement opportunities will never be achieved without these three elements working together. Indeed, the original concept of ERTMS was to have a traffic management element, although that has not materialised as expected.

Another factor in the capacity debate is degraded mode operation – how to keep trains moving when the primary signalling system is in trouble. All three elements have to be part of this, maybe incorporating intelligence into the COMPASS (Combined Positioning Alternative Signalling System) scheme for temporary block working (issue 129, July 2015).


The specifications for the use of packet switching (GPRS) for GSM-R transmissions were approved by the EU on 10 February 2016, paving the way for introduction. This will give sufficient capacity for ETCS operation in the near-to-medium term. In the longer term, however, a more flexible radio bearer will be required and, rather than devise and negotiate a bespoke rail solution within 4G or 5G, the RSSB view is for a ‘bearer agnostic’ approach to be taken. The idea would be to concentrate on the functionality rather than the technology and RSSB is supporting the UIC and working with the European Rail Agency (ERA) to specify this.

In theory, it could mean using whatever system has the strongest signal at a locality, be it public mobile radio, Wi-Fi, or a railway-provided private radio network. The implications are considerable, particularly for the security and continuity of the radio signal coverage.

Security and safety

RSSB has been commissioned to develop a cyber security strategy for the rail industry. To support this, an advisory group has been created which includes academia, train operators, Network Rail, Crossrail, safety and security experts and even the Police. This group will form a basis for co-operative working amongst all players in this most complex of railway systems.

International links and the future

Although there is no specific group to which RSSB belongs in Europe, there is a strong informal relationship with many European railways and close co-operation with the ERA. Network Rail, as part of Digital Railway, has signed a memorandum of understanding with ProRail of the Netherlands to seriously investigate the advancement of ERTMS Level 3.

This has been a dream for over twenty years but so far has made little progress. Technically from a train perspective, it is not so different to Level 2 but is essentially a different way of reporting train position by using only radio bearers and distance measurement from track-mounted balises. A sticking point has always been proving the integrity of a train (that it has not become divided). This is not a problem for passenger trains where through-wiring is an integral part, but freight trains can and do become uncoupled for a variety of reasons. Much could depend on the development of the ‘smart wagon’ concept, which is akin to the technology applied to modern day containers that contain electronics to monitor temperature, humidity and other conditions. Talk of an ‘intelligent tail lamp’, using radio to communicate from the train rear to the locomotive, is perfectly possible but logistically is a bit of a challenge.

The RSSB with its considerable influence sees ERTMS as an important feature in developing modern train control. Tom Lee will no-doubt amplify his views at ERTMS and ETCS 2016: The Future of Railway Signalling in the UK, a conference organised by Waterfront on 22/23 March at Stephenson Harwood.

For more information on ERTMS and ETCS 2016: The Future of Railway Signalling in the UK, visit www.waterfrontconferencecompany.com