As the head of Network Rail announced on March 31st of this year, the UK national railway system is facing a substantial overhaul, with planned investments of around £35 billion pounds over the next five years, or Control Period 4, ‘delivering improvements in safety, performance, capacity and availability’. One central aspect of this ‘railway revolution’ is the transformation of railway signalling.
Many signalling systems comprise dated technology using traditional red, yellow and green lamps, which imposes significant limits on the frequency of trains and thus available travel schedules. In the current standard arrangement, large sections of railway tracks must remain empty until the train currently passing through has signalled its exit – even though it would often be possible to fit several more trains on the same section or block – provided the trains were location-aware and could stop safely. Traditional signalling thus severely limits train throughput. By contrast, intelligent signalling, by moving from fixed block signalling to moving block signalling, can allow more trains on the same line, offering more frequent, faster and safer rail services without any amendments to the network itself.
The next big step in this evolution of railway signalling could be ERTMS (European Railway Traffic Management), an in-cab signalling and train control system developed by six UNIFE members in close co-operation with railway stakeholders, the GSM-R industry and the European Union. Rather than relying on traditional trackside semaphores, this system can use the GSM-R network to communicate trains’ position to a central control room. The system incessantly calculates how fast the train can go while still being able to brake and stop within the specified distance at any instant, and advises the driver on the maximum speed or movement authority. In theory, ERTMS/ETCS (European Train Control System) could impact positively on all the areas which Network Rail is looking to improve: capacity, availability, performance, and safety – even cost reduction.
Unfortunately, the deployment of the system is not so smooth a ride in practice and actually faces some serious obstacles. ERTMS/ETCS has been more successful outside of the European Union, one of the primary sponsors of its development, than inside it. Though it has the simplification and interoperability of train control systems among its primary objectives, the complexities of the different levels of implementation, which will be explained in more detail below, have left infrastructure owners confronted by problems over integrating ERTMS/ETCS with existing rail systems and infrastructure.
For example, ERTMS/ETCS in its ultimate stadium relies on the use of optical fibre networks as opposed to traditional line-side copper cables. Even the GSM-R system which provides movement authority to the trains in the most basic version of ERTMS is dependent on reliable fibre links from the base station to the Radio Block Centre. Thus, the farther signalling technology progresses, the more it will be an integral function of reliable, state-of-the-art telecommunications. In major parts of the UK, this telecommunications prerequisite is already in place, as Network Rail commissioned Alcatel-Lucent to supply optical nodes for the new Fixed Telecom Network (FTN), which is an ongoing operation. However, not all regions of Europe have upgraded their infrastructure accordingly yet.
The height of the irony is that equipment built for different ERTMS/ETCS levels can actually be incompatible as well. Thus, Switzerland has had to remove ERTMS from one line because of its incompatibility with other level versions installed elsewhere.
As a result of such teething problems and no compelling reason for interoperability, the debate over whether ERTMS is the right way to go for the UK is unlikely to end soon. For the UK, European interoperability is not necessarily the biggest driver for the huge investment in ERTMS anyhow – as only a few trains per hour pass through the Channel Tunnel and they have a dedicated track to St Pancras. Yet the gains in line capacity and reduced maintenance of line-side signals across the country could be driving the business case for the UK‘s railway. What follows is a more detailed outline of the potential benefits to be derived from ERTMS, provided its current problems can be overcome.
ERTMS covers the use of both GSM-R and ETCS. There are three levels of implementation of ERTMS/ETCS. At level I, movement authority is passed to the train via balises or transmitters, repeating indication from existing trackside signalling. At level II, movement authority is passed continually by radio from a radio block centre to the train, with intermittent updates of the train location. At level III, ERTMS/ETCS provides continuous updates on movement authority and train location. It enforces train separation using position data from the train rather than trackside train detection.
With the current signalling system of trackside signals up to 10-15 miles apart, forming fixed blocks of tracks, each train uses two blocks by itself at any one time as the stretch ahead of it needs to be kept free as well. ERTMS/ETCS level III would make trains location-aware, meaning the continuous communication-based signalling system can locate train A relative to train B, which in turn means that the distance required between them needs to be no more than the safe braking distance. The network would thus use moving block signalling, which significantly enhances its capacity as compared with the restrictions imposed by fixed block signalling. (Of course, in areas of poor network coverage, for example in deep cuttings or tunnels, the system can revert back to use of balises or beacons to provide continuity.) Without changing the physical infrastructure itself, the network could thus potentially accommodate up to 40 per cent more rail traffic.
Enhanced network capacity has direct implications for service performance: train services would be more frequent, punctual and faster. The ability to put more trains on the track at any one time would allow for more frequent connections, transporting more people, and more of those transported seated. Assuming fewer signalling failures due to ERTMS/ETCS being less dependent on trackside mechanical equipment, the system should also improve punctuality. Furthermore, location awareness would allow high-speed trains to actually meet their maximum speed of around 500km/h, track infrastructure allowing.
While the current signalling system is relatively very safe already, the new radio-based signalling could provide an automatic self-stop as an overriding safety feature, cutting out train drivers’ reaction time, and thus ensuring the train can keep within the safe braking distance.
ERTMS is also intended to reduce the cost of railway networks. One potential cost reduction derives from lower maintenance required, as with system levels II and III, trackside signalling would no longer be needed (though maintenance cost for base transmission stations will remain). Another source of cost savings is based on the (theoretical) interoperability of the system – which is also one of the primary motivations for developing the system from the perspective of one of its main investor’s, the European Union.
Currently, there are over 20 different and incompatible train control systems in place across Europe – which means trains often have to be equipped with more than one system just to be able to run safely within one country. Not to speak of the high costs associated with cross-border traffic: the Thalys train services between Paris, Brussels, Cologne and Amsterdam, for instance, have to have seven different types of train control systems installed. ERTMS/ETCS aims to replace the different national train control and command systems with one seamless European
A single standard system will ultimately be easier to maintain and manufacture. The resulting increase in competition on the supplier market should in theory also lead to network cost savings, in addition to the TOCs’ savings from having to install only one train control system onboard their fleet, the argument for ERTMS goes. The overall increased efficiency of rail networks through ERTMS may even boost Europe’s green credentials as people and goods shift back to railway from air and road transport.
ERTMS level II is currently in its trial phase with equipment and software supplied by Ansaldo on the Cambrian line in Wales. The fact that the previous radio signalling on the Cambrian line was in dire need of replacement provided a welcome opportunity to test the system. But important commuter lines such as the Thameslink project are still avoiding ERTMS/ETCS, which is still perceived to be too immature and expensive by many.
The Cambrian service is expected to become operational within 2009. It remains to be seen whether the adoption is deemed a success. If it does prove itself, the Western region between Paddington and Bristol is most likely next for ERTMS. However, the challenges posed by the West of England mainline will no doubt be far more stretching than those of the relatively simple Cambrian line.
Bob Herritty is the transportation market director at Alcatel-Lucent. Bob has more than twenty years’ experience in the transport industry. He has previously held roles inside Alcatel-Lucent as the vertical markets sales director in the UK, managing director of Alcatel’s Saft Power Systems Ltd business unit in London, and managing director of Saft Singapore Ltd in Singapore. Bob also spent 14 years developing business for Alcatel transport-oriented speciality business units in North America.