Signalling Solutions
An integrated approach for Digital Train Control projects With the use of Digital Train Control systems on the rise, there is a growing need for efficient Systems Integrators to manage the process. Railways across the world are striving to deliver more capacity and reduced journey times, aiming to improve safety and performance in terms of reliability and resilience, and increase environmental and financial sustainability. Satisfying these competing demands is beyond the capability of conventional signalling and control systems, and has led to the introduction of Digital Train Control (DTC) Systems based around European Train Control System (ETCS) Level 2 and Communications-Based Train Control (CBTC) technology. These new, more centralised DTC technologies significantly reduce the need for maintenanceintensive signalling equipment within the rail corridor, creating a safer, more operationally efficient rail network environment. DTC systems, however, are inherently more complicated than conventional signalling systems, using over-the-air data communications to provide in-cab signalling, whilst also monitoring and enforcing correct train movements and speeds. But the benefits are substantial. From an operational performance perspective, DTC systems can automatically manage extensive and complex networks, deliver high-capacity service outcomes, and perform network-wide regulation and optimisation in the event of delays and incidents. They are increasingly able to interface with other systems for broader planning and management, such as rolling stock fleet, train crews, incident management, customer information, etc. IMPLEMENTING DIGITAL TRAIN CONTROL PROJECTS According to GHD Global Technical Lead for Digital Train Control, Stephen Lemon, the challenges for projects introducing DTC systems are significant. “The DTC system is actually a system of systems, made up of highly complicated, softwarebased technologies – and implementing these requires a significant integration effort,” he said.
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“In addition to the technical integration, there are also many interdependencies between the technology and the ways of working associated with operations and maintenance.” The upshot, Lemon said, is that there is a parallel requirement for extensive ‘operational integration’ to ensure that the delivered DTC outcome – an integrated system of people, process and technology – is both operable and maintainable. “System integration can therefore be seen as the combination of technical integration and operational integration in a system of systems,” he said. “Once we take into account that we are not just integrating a system of people, process and technology, but – when we consider a brownfield environment – we are also integrating that into a much broader, established system of systems, ie. the existing operational rail network, then our challenge shifts from being a ‘complicated’ one to being a ‘complex’ one, and this distinction is important.” MANAGING UNCERTAINTY Lemon states that complicated problems involve a lot of elements and can be difficult to solve, but they involve ‘known unknowns’: things that are currently unknown, but are understood and ‘knowable’. “They have cause and effect relationships with root causes and can be solved through detailed analysis,” he said. “Complicated projects require more expertise in their management, but they can generally be managed successfully with a rulesbased approach. “Luckily, there are plenty of ‘complicated’ methodologies in the systems engineering toolbox that will help lead us to a successful project outcome in these cases.” However, complex problems (and projects) are essentially systems that involve many interdependent, sometimes unknown elements, and often change over time in unpredictable
ways. Actions or change in one aspect of a complex system can often have entirely unforeseen and disproportionate outcomes. “We can also see that a train is complicated, whilst operating a railway would definitely be complex – and delivering a DTC project into that railway even more so.,” Lemon said. The big challenge of complex systems and projects is that they do not have pre-existing cause and effect relationships, and they do not lend themselves to an absolute or definitive ‘correct’ solution. “In a ‘complex’ environment, you need to recognise that an inflexible ‘complicated’ approach will not be effective, and a more nuanced, strategic approach is required to achieve an effective outcome,” Lemon said. “You should aim for progress rather than perfection, and problems will need to be managed rather than solved.” INTEGRATING THE SYSTEM A dedicated ‘System Integrator’ organisation, supporting the client throughout the entire project lifecycle, and acting independently of any system and subsystem suppliers or delivery organisations, is one way to address this complexity and uncertainty challenge. But Lemon warns that for this to be effective, there needs to be a clear understanding of the difference between the formal systems engineering and assurance activities associated with ‘complicated’ system integration, and the management of uncertainty through more strategic, ‘complex’ system integration approaches. THE ROLE OF A SYSTEM INTEGRATOR The System Integrator’s role ensures that the ‘intent’ of project owner/sponsor strategies and objectives are interpreted correctly, fully understood and properly maintained throughout a project. “This strategic alignment is often less quantitative or formally traceable compared with
