Revolution in modular form
05 Jan 2010
It has been said that nothing great in the world has been achieved without passion. We don't hear that word mentioned a great deal in the context of railway engineering which is a pity because it exists in abundance. It's refreshing therefore to hear a project manager from Invensys Rail, Richard Inglis, talking openly about the passion and conviction he has found within Network Rail and his own team, working in partnership on a revolutionary new signalling project.
"It has been called ‘Modular Signalling' and Invensys Rail (formerly Westinghouse Rail Systems) and Network Rail have been working on it for two years. In essence it will provide a cost-efficient means of implementing new signalling schemes by using highly-standardised modular components. By simplifying and standardising the engineering solutions, delivery practices and client requirements, we've developed a modular signalling solution that provides value for money, is future-proof and which can be delivered in the minimum time."
The project brings together several key elements and products from across the Invensys Rail companies. None of these were developed specifically with modular signalling in mind but, by pooling them together, Invensys Rail has been able to produce a signalling system that is radically new.
WESTRACE
At the heart of the Modular Signalling solution is the ‘Westinghouse Train Radio and Advanced Control Equipment' (WESTRACE) microprocessor-based interlocking system. This has been used extensively abroad but, in the UK, it is probably best known for its role on London Underground's Central and Victoria lines as well as being the basis for ERTMS.
Richard Inglis goes on to describe how it works. "WESTRACE functions as a Programmable Logic Controller, comprising Vital Logic Equipment (VLE), a Diagnostic Module and up to 128 Input/Output Modules (IOMs) - more than enough to cope with even the busiest of layouts. Each Processor Module (PM) can be likened to an industrial super-PC that makes use of ladder logic. All of the modules incorporate ‘2 out of 2' architecture and have full compliance with CENELEC SIL4.
The PM contains configuration data, carries out vital processing and manages internal and external communications. Each one comprises three interconnected microprocessors - two form the vital processing core, performing the interlocking logic and cross-checking each other, whilst the third executes diagnostics and network communications functions."
For the Modular Signalling project, the intention is to use a new Mk2 version of the WESTRACE interlocking. This takes advantage of the latest production techniques to provide an interlocking system that offers increased flexibility, configurable redundancy and four times the data capacity of the original WESTRACE. The new system has also been consolidated into hot-swappable Line Replaceable Units (LRUs) which are mounted in one double-height (6U) Eurocard chassis.
A key feature of WESTRACE Mk2 is that all the programming is done off site. As Richard Inglis explains, "We will be using a sophisticated configuration tool known as the Graphical Configuration Sub-System (GCSS) that allows railway signalling engineers to design the application-specific vital logic data. Once the data has been written, it is downloaded to the Processor Module. The Graphical Simulator (GSIM) allows the engineers to simulate the logic they have designed and downloaded prior to installing it on site. This is to be done by using a graphical representation of the railway. The GSIM is considered part of the GCSS. The GCSS, GSIM, ICS and application procedures together make up the Graphical Configuration System (GCS)."
In simple terms, all the hard work is done off site in a controlled environment. The LRUs are ‘plug & play' and self-configuring, cutting down the amount of testing required on site.
Connectivity
Communication between the Processor Modules and the outside world is via Input/Output Modules. The range of IOMs is extensive, including signal and point operating modules, relay output modules, lamp output modules, coded input modules and parallel input modules. IOMs can be located together with the Processor Modules or up to 40km away, communicating by Fast-Ethernet over fully duplicated fibre optic links. Fibre links - indeed any Ethernet-enabled communications system - can also be used to allow communication with other equipment such as ECTS Radio Block Centres, WESTLOCK interlockings or other WESTRACE interlockings.
The Modular Signalling system does not use conventional location cabinets. Devices known as Object Controllers (OC) provide the interfacing between the WESTRACE Input/Output Modules and the trackside ‘objects' such as point machines, signals, track circuits and axle-counters. The OC concept is again modular, using basically the same core components as the interlocking itself. By using OCs, the need for banks of conventional miniature plug-in relays has been eliminated and consequently the lineside cabinets are much smaller than standard location cases. Each OC contains common components with direct connection with the objects.
Richard Inglis is keen to point out that "All of the equipment runs on low voltage, low current DC. That means there's no need for heavy copper cabling. We've also got away from using heavy, inefficient and expensive transformers. This all adds up to a significant cost saving."
Lightweight signals
The trackside objects such as signals, points or train detection are all low power devices requiring minimal maintenance. Structure design aims to eliminate the need for substantial supports or foundations. To this end, Invensys Rail and Network Rail have been working closely with Variable Message Signs (VMSL) on a new range of super-lightweight LED signals. These are evolved from VMSL's LED Banner Repeater Signal, as featured in December's issue of the rail engineer. They also use the high performance optical technology from VMSL's approved Colour Light Signal. Developed initially to support the requirements of the Modular Signalling initiative, this new signal range will also be available for non-modular applications.
A number of novel features are employed, offering the primary benefit of extremely low weight whilst meeting all of the Network Rail compliance criteria. For modular applications, the signals will be supplied fitted to a lightweight structure that can be easily and quickly installed and commissioned on site at ground level, without the need for lifting equipment. For non-modular use, the signals can be mounted on a conventional footprint.
The first application of Invensys Rail's Modular Signalling solution will be on the Shrewsbury to Crewe section of the Western route. In June 2009, Invensys Rail was awarded a contract by Network Rail covering the GRIP4 development stage of the pilot scheme and a demonstration of the proposed solution. The trial will use a distributed architecture and, although one central WESTRACE could be used to control the entire route of the pilot scheme, four or five distributed WESTRACE interlockings will be installed to provide greater flexibility as well as easier modification and testing. It is proposed that level crossing control will be achieved by fitment of the WESTEX GCP4000 predictor system; this however is still being developed during GRIP 4.
Opportunity
Network Rail needs to deliver significant signalling renewal cost efficiency over the next five years and beyond. Modular signalling will play a key role in achieving this whilst future-proofing the need for a signalling system that is easier to enhance with an upgrade path to ERTMS.
"This has been a fantastic once-in-a-lifetime opportunity for a company to directly influence the evolution of railway signalling" says Richard Inglis, summing up Invensys Rail's involvement. "We're grateful to be involved with Network Rail on this and to move forward with them. Because modular signalling is so different, there have been some tough challenges. But all of the personnel involved in this project here at Invensys and at Network Rail have a passion and conviction that will see it through to the delivery phase."
"As signalling engineers we have two key aims - to keep people safe and to enhance people's lives by allowing the railway to operate efficiently. Everything has to be done safely so there's a temptation to leave things alone. People in this industry have often been nervous of change but now we're living in a world where we can't ignore financial constraints. Here we've had a great opportunity to react to those constraints and, at the same time, push the technological boundaries forward."
By placing WESTRACE Mk2 interlocking and commercial networking at the heart of the system, Invensys Rail has developed a complete, flexible, modular and scaleable signalling solution.
Article courtesy of the rail engineer magazine. Photo courtesy of MATTBUCK4950.