Periodically, the signalling and telecommunication profession demonstrates and shares its technology and innovations, safety policy, business methods and finances as seen by rail infrastructure organisations, train companies and the supplier base.
Most recently, this was achieved through a five-day convention in Glasgow, organised by the IRSE. The subject matter had a Scottish flavour but the success stories and lessons to be learned had relevance for all the UK railways and many overseas railways as well. With attendees from right across the world, it was remarkable to hear during the socialising sessions, just how many of the problems being experienced in Britain were the same elsewhere. With a mixture of talks and technical visits, real progress was evident in some areas, though deployment of the game-changing technology that could yield substantial commercial benefits continues to struggle.
Current signalling technology
British Rail led the way back in the 1980s in the development of computer-based signalling commonly known as Solid State Interlockings (SSI). This took many years of tripartite co-operation between British Rail, Westinghouse (now part of Siemens Mobility), and GEC (now part of Alstom) to get an acceptable product standardised and approved for general use. The computer technology has moved on from those early days and improved versions of the interlocking have evolved into WestLock from Siemens and SmartLock from Alstom. Both have much greater computing power but retain the same data formats. Being bespoke products, they are expensive and increasingly only used where much of the associated trackside equipment is to be retained.
Ben Hugh from Siemens Mobility described an alternative approach that provides a complete solution for all the required signalling intelligence including the interlocking. Known as the Westrace Trackside System (WTS), this may be regarded as a ‘toolbox’ of Westrace units. The interlocking element is designed as ladder logic and was first used on some metro line projects including the London Underground Central Line upgrade. Westrace uses standardised templates which leads to faster designs with pre-wired components, this allows factory testing such that when the system leaves the test yard, it is known to work.
Another objective is to cram as much equipment into the lineside equipment room, itself being designed with a modular layout. This results in fewer lineside cases and thus fewer maintenance visits. External elements such as points and signals are connected by plug-coupled tail cables, measured beforehand to be the correct length. Each Westrace unit is a standard module design (e.g., a point module, a signal module, etc.) such that multiple connections can be made into one unit. Thus, a point module might be capable of serving, say, four point machines. If only one point machine is served, it might seem that the unit has more capacity than needed but the fact that it is standardised means that overall cost saving is achieved.
Westrace is designed to provide better remote condition monitoring including earth leakage detection with connection to third-party non-SIL equipment. Future developments include the use of cloud diagnostics and the use of alternative transmission links to replace customised cables. These might include low-powered radio and existing lineside comms. The WTS installed base is impressive and includes London Bridge, Derby, Liverpool Lime Street, Kings Cross, and, most recently, Macclesfield.
Lower cost signalling
The cost of signalling is a contentious issue and several initiatives have occurred recently to provide more cost-effective technology, especially for rural lines. Park Signalling made much of its replacement design for a lookalike single line token instrument. Known as DiBloc, this is a digital block controller that connects to other instruments using secure IP Communication. A full description of the system was given in Rail Engineer Issue 174 (May 2019) so will not be repeated here. The first application has been on the Romney Hythe and Dymchurch narrow gauge railway in Kent and a contract is let for the Whitland to Tenby line in West Wales. There are still a few single lines that are operated by token machines so, although the market is not huge, it is significant and may have opportunities for overseas railways.
Radio Electronic Token Block (RETB) has been around for over 30 years but recent work to improve performance, partly necessitated by a radio frequency change, has made the system more reliable with more features. Under a main contract with Telent to provide overall delivery, both the West Highland Line and the Far North lines in Scotland have benefited from the upgraded system. Whilst the basic principles of a chain of radio links from the control centres at Bannervie and Inverness remain, the radio network has been completely renewed with equipment being designed and supplied by Comms Design Ltd, a Harrogate company specialising in bespoke radio equipment.
These lines are in remote areas and very often there are no passengers to join a train at the stations. To avoid the driver having to slow down in case a passenger is waiting, Request Stop units have been developed by Park Signalling linked into the RETB network. On the platform, a unit is provided that gives the time of the next train services, usually in both directions. A button is then pushed to request the train to stop, with this then being posted on to the driver’s RETB token screen. Currently being trialled at Scotscalder, it is expected that these units will be rolled out to all stations on these lines.
RETB seems to be a genuine low cost signalling system for rural lines. Elsewhere in the magazine there’s an article about efforts to reduce signalling costs, and virtually every one of them seems to be fraught with problems that are likely to increase costs. I felt the author, a much respected retired senior signalling engineer, was struggling not to be cynical about it all. https://www.railengineer.co.uk/affordable-signalling/
In this country at least, the costs of signalling are increased by a continuing staff shortage, dating back to privatisation ….
When privatisation was announced, there was an immediate recruitment ban. { “Private Industry is so much more efficient, we won’t need all these people, anytway” }
Needless to say, this turned out not to be the case, but the problems are still with us.