Rail transport is already a complex system, pivotal to integrating our transport network into a larger system engineering whole 

What is rail transport?

Urban and inter-urban rail is a high-speed solution for the transport of people and goods. While roads are mainly focused on individual transport solutions, rail is mass transit with similarities to air and sea transportation; it is organised as a network, centred on major hubs. The rail network connects interchange points (for example, passenger stations or freight terminals) and other transport modes. Rail Systems Engineering (SE) is inherently a “system of systems.”   

Why does rail matter?

Railways connect goods and people through mass transit operational models. In the year to March 2022, UK railways accommodated 990 million passenger journeys and 16.87 billion tonne-kilometres of freight. In 2019, the rail industry supported £43 billion in economic production, 710,000 jobs, adding £14 billion in tax revenue.

Rail affects sustainability because it has a smaller carbon footprint than other transport modes on a per passenger basis. Similarly, rail freight contributes to carbon reduction targets in the large-scale movement of goods across long distances.

Systems engineering in rail

Railway systems engineering is traditionally based on the application of the V-lifecycle and process of top- down decomposition, with associated verification and validation as documented in CENELEC standard EN50126 (or IEC 62278). This approach enables progress assurance to be demonstrated to external regulators, minimising the risk to safety and performance.

The ‘V’ lifecycle

Early lifecycle stages (the Concept, System Definition and Risk Analysis) are generally the responsibility of the Railway Authority (the railway operator or owner of the infrastructure) when existing networks are being improved. These stages derive safety and RAM (Reliability, Availability and Maintainability) targets that drive the specification of the system function. Requirements development and the subsequent lifecycle stages are then a shared responsibility between the system integrator, usually the railway authority, and the train operating companies who developed the system developer. These parties are responsible for specifying the system, as well as allocating function to subsystems.  They ensure the overall verification and validation is performed to guarantee that the delivered system meets the specified requirements, before activating the delivered system into operation. The CENELEC process is inherently “top-down”, even if feedback loops from the subsystem subsequent activities must be accommodated. 

Morant’s Curve, Improvement District No. 9, AB, Canada Source: Andy Holmes on Unsplash

The future significance of SE for rail

Systems engineering is already a critical tool for developing the complex systems that characterise turnkey railway solutions.

As Mobility-as-a-Service continues to evolve, the complexity of interfaces between both rail systems and rail systems with other transport modes continues to increase. One of the key systems engineering activities is the accurate identification, specification and testing of interfaces. It’s importance in managing emergent properties across interfaces is fundamental given the safety critical nature of these systems.

Systems engineering in rail is increasingly important in defending against threats posed by cyber-attacks.  It matters, too, and in achieving a safe balance between autonomy and human performance, as Artificial Intelligence becomes more widespread.

It is already clear from some of the earlier applications of Model Based Systems Engineering, that these tools and models will enhance the ability to integrate with other sectors. Both for the transfer of goods or passengers but also the decarbonisation of rail. This last factor relies on the interface with appropriate green energy sources or more likely a combination of decarbonisation options. The history and tradition of railways is also a factor in rail solution complexity, as rail moves to address the challenge of interoperability in an environment, which is quite often a legacy environment, with extensive national and international standardisation.

Challenges in applying SE in rail

Systems engineering is fundamental to railway processes through the common application of the CENELEC standard, EN50126.

Pressures to bring systems to market faster often threatens the use of systems engineering fundamental concepts, such as deriving requirements before undertaking design. A better understanding of fundamental systems engineering concepts and their value is needed to ensure the principles are properly applied and respected.

Case Study – Lessons from Crossrail

London's Crossrail is an ambitious rail project providing faster journeys from Heathrow Airport and Berkshire in the west to Essex in the east, through a series of new tunnels under London. The central section of Crossrail opened in May 2022, with scheme completion planned for May 2023.

Crossrail opened three and a half years late and more than £4 billion over budget for a total cost of

£18.8 billion. Problems with the signalling system and rolling stock integration, integration of digital assets, system assurance and handover to operation all contributed to the delay.

The benefits of system engineering practice and system risk management in large projects are not always widely understood by Sponsors, Programme Directors and Project Managers.  The result is misaligned contracting and integration strategies, poor systems delivery governance and poorly managed systems risks. As system risks mature, the impact of delay and cost over-run is high, compared to the typical system contract value.

Building relationships

The importance of a strong relationship between systems engineering teams and other project teams is key.  There is a need to improve understanding between systems engineers and non-technical project staff. This system-led communication has to start early in the process to maximise the value for a project. System engineers need to consider the stakeholders they are trying to communicate with, and choose appropriate language to manage that message. The use of domain examples rather than abstract ‘systems speak’ is just one point to consider. To be successful, system engineers must be able to integrate with project teams who are not conversant with systems engineering terminology.

Improved communication should address problems related to the lack of understanding of how technical requirements and delivery link with procurement and contract management activities to deliver the most efficient version of success. Systems engineering should not be solely considered a delivery discipline. Rather, it is fundamental to the early establishment of system requirements, definition of procurement and contract integration strategies.

Chemical reactions

The perception amongst project managers that systems engineering takes too much up-front time and effort, whilst delivering little immediate benefit has been recognised. There is an acknowledgement that system engineering language can be difficult to interpret by non-technical project teams.  This can undermine the understanding of the benefits of the systems approach. The result is that systems engineering is regularly seen as a reactive discipline used to solve problems late in project delivery, rather than implemented early to reduce the likelihood of those problems emerging in the first place. This situation appears to be consistent with the Crossrail experience, when systems engineering was applied late in project delivery in an effort to mitigate delay. 

Constructive understandings

There is a continuing need for systems engineers to demonstrate the value of systems engineering to the wider project community. Systems engineering is the glue between teams. It helps by capturing different stakeholder needs in context, modelling the systems involved to provide a rational basis for change management and assuring business requirements are achieved. The systems community needs to show that the discipline supports greater commercial understanding of complex systems delivery, which has a positive impact on outcomes, budget and timescale, reducing waste and increasing delivery confidence.

A system that requires integration at technical, operational and commercial levels to succeed requires systems engineering to achieve this. Systems teams need to ensure  project managers, and other project team members, understand this value in financial terms. Project managers then need to be supported in integrating systems engineering planning within the wider project delivery plans. This is particularly important when projects are large and unique, as was the case with Crossrail.

Share your thoughts!

What role can Systems Engineering play in making Rail more responsive to the needs of passengers?

How can Systems Engineering be of use when integrating Artificial Intelligence into the rail network?

What would adopting a Systems Engineering approach early in a rail project bring to the project as a whole?

How can we make System Engineering compatible with the commercial demands and pressures of any rail project and system?

#thewholesystem