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 maintenance-intensive 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, software-based technologies – and implementing these requires a significant integration effort,” he said.
“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.”
Complicated vs complex
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 rules-based 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.
“An example of a complicated system might be a car, whereas traffic would be considered complex,” Lemon said.
“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.”
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.
They involve the ‘unknown unknowns’. According to Lemon, the inherent uncertainty in complex projects will naturally make a lot of people uncomfortable – “that’s a normal reaction to unfamiliar and unpredictable situations” – but it does not mean things cannot be managed effectively, it just means doing things a little differently.
“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.
“An excessive emphasis on an early ‘lock-in’ of requirements in complex DTC projects can lead to a false sense of security, and then escalating costs, risks and delays at the back-end of the project.
“However, acknowledging and managing the inherent uncertainty within a complex project requires an appropriately flexible and agile working environment, with the ability to continually course correct as needed, and with suitable supporting governance arrangements. “This is a very different approach to that required for more conventional infrastructure projects, and it requires a specific intent in the set-up and management of DTC projects to achieve an effective outcome.”
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 the detailed system and subsystem requirements,” Lemon said.
“This results in significant ongoing risks that project outcomes will be inadvertently and unknowingly compromised by low-level decisions made for project expediency and where the knock-on effects in a complex project tend to be unpredictable.
“A key aspect of complex system integration is to ensure that decisions around the configuration of system parameters and design solutions are objectively and strategically optimised, balancing the demands of project delivery with the broader, longer-term, whole-of-life implications.
“This process is critical for project success as it can significantly alter the overall project outcome in terms of its impact on network performance, reliability, resilience, environmental sustainability, safety, and the cost-effectiveness and ultimate financial sustainability of operations and maintenance.”
Lemon said engaging a dedicated System Integrator is not a panacea for all complex project ills, and nor is it some kind of ‘get out of jail free’ card for the client – it should be seen as an outsourcing of responsibility not accountability.
A System Integrator needs to work hand-in-hand with the client, acting on their behalf, ensuring balanced, objective decision-making, and leading to an optimised outcome where benefits are fully realised.
“The contractual set-up for the client, System Integrator and other key stakeholders must support this, and facilitate and engender collaborative working relationships between all parties to have any chance of success,” he said.
Operator and maintainer (O&M)
It is also essential that a System Integrator is able to work closely with the operations and maintenance organisation to ensure that the integrity of the O&M ‘intent’ is maintained throughout the project.
“This is another area fraught with risks and pitfalls,” Lemon said. “System OEM suppliers have limited experience of integrating their systems into operational networks, and different countries, jurisdictions and networks have different rules, characteristics, ways of working, risk profiles, etc.
“At the same time, O&M organisations have embedded ways of working that have evolved over many decades, and resistance to change is a natural and powerful force – and one that isn’t very helpful for complex DTC projects.”
A key risk associated with this aspect of complex system integration – and therefore a key focus for the System Integrator – is to address the O&M needs, whilst trying to avoid any preferential and prescriptive requirements that might lead to customisation.
Bespoke approaches in a complex system can escalate project risk significantly, and divergence from international standards and supplier technology roadmaps can create unnecessary challenges in achieving and maintaining interoperability, as well as dramatically increasing the costs and risks for future upgrades and augmentation.
The challenge of complex system integration in DTC projects is to ensure that a multitude of interdependent systems and subsystems work well together in a complex integrated ‘people, process and technology’ ecosystem.
It is also important that network performance and benefits are not compromised, with the integrated ‘system of systems’ unwittingly becoming less than the sum of its parts.
The GHD service
GHD is a global professional services company that leads through engineering, construction and architectural expertise.
“GHD efficiently manages projects as a Systems Integrator, dealing with the complex challenge of integrating new systems and technologies,” Lemon said.
“GHD works hand-in-hand with clients and their suppliers as an objective, trusted advisor to help them in the development and delivery of DTC projects.
“We help to ensure that the solution is specified to deliver optimal benefits and is suitable for its intended operating environment.
“Our approach also ensures that the delivery project manages the inherent uncertainty and challenges that come with DTC projects.”