How systems integration made Crossrail a reality

But Crossrail’s legacy extends much further than the step-change in connectivity it represents. As well as boosting economic growth and regeneration, in and around the capital, the Elizabeth line will be a steady source of employment for many over future decades. A potentially bigger impact will be in the skills development Crossrail has enabled during design and construction, and at a time when UKPLC looks to develop the next generation of experts who will deliver future transformative infrastructure. The vast legacy of lessons learned and innovations implemented on this once-in-a-generation project will better inform infrastructure projects of the future.

What was at one point Europe’s largest infrastructure project, the Elizabeth line’s recent and much-anticipated opening was the result of a gargantuan effort involving multiple parties, contracts and many moving parts.

Its delivery owes a great deal to an often-overlooked hero of infrastructure delivery: systems integration.

Failure not an option

Having missed its December 2018 opening deadline, Crossrail diagnosed the critical need to fully integrate the railway and overcome the complexity challenge. WSP was duly appointed to establish and lead a system integration (SI) capability; in early 2019, just two weeks after the request from Crossrail, WSP had mobilised a dedicated SI team ready to set about re-baselining the entire programme. 

To solve Crossrail’s complex integration challenges, WSP needed to apply all the lessons we had learnt from applying systems integration over the past 20 years on major rail infrastructure projects such as the Victoria Line Upgrade and Thameslink. In this way, the WSP team was able to take advantage of project-specific experts from within the project (i.e. not exclusively from any one organisation) in combination with our railway operations and rail systems subject matter experts. Through our tried and tested whole-system approach , the WSP team sought to integrate programme-critical factors, from software management and the evolving status of station readiness to the testing and commissioning phases needed to meet its final revised opening deadline of May 2022. 

This time, Crossrail would be delivered as promised.

Unpicking complexity 

The original plan – to hand over a fully completed, authorised and operable railway, but staged geographically – was unpicked and re-developed in favour of a combined geographically and functionally staged (or “migrated”) approach. Through its new Earliest Opening Programme (EOP) strategy, Crossrail would be able to unlock passenger benefits as soon as possible, ultimately providing London with a new east-west passenger service in a way that minimised costs and maximised efficiency. The strategy’s success was contingent on three key tasks: 

• Defining what needed to be changed to enable a migrated railway
• Resolving complex and novel technology challenges 
• Ensuring the migrated capability was operable

Defining the migration

To support Crossrail’s EOP strategy, a migration plan was developed by WSP that would present technical and non-technical stakeholders with the logic needed to reach each milestone (e.g. testing & commissioning and health & safety assurance milestones), and for schedulers to define the critical path with certainty. And it would do so all “on a single page” to simplify the communication of the complexity involved. 

Created using WSP’s field-proven approach to systems integration, known as SI:D³, the migration plan became a hero of Crossrail’s eventual success. Critically, by revealing inter-relationships and redefining levels of capability the WSP team was able to clearly set out a new approach to staged completion of Crossrail. Particular attention was given to the complex signalling, rolling stock and stations; ultimately defining the required minimum acceptable functionality and scope required to deliver them.

For the first time, the reality of where the dependencies on this complex programme existed could be understood by everyone, instilling confidence in the programme. A new framework was implemented to ensure configuration stages would be achieved on time and further support the authorisation and assurance of the delivered railway. That the trial running date, trail operations and entry into service dates occurred on schedule, showed how reliable the migration plan was.

Building back trust

The Crossrail programme is characterised by its complex contractual environment, which created a unique and challenging context within which multiple new systems had to be delivered together. The most complex was the Elizabeth line’s three signalling systems*, a never-before-seen combination of software and hardware that would need to integrate with other networks, for example, Network Rail’s main lines. To manage the integration of complex and unique signalling and rolling stock solutions that would ensure the new and legacy systems worked as one, the project needed a guiding mind. Step forward Plateau, a WSP-led team of representatives from Crossrail, Siemens (Germany and UK) and Bombardier (UK and Sweden), MTR, Network Rail, RfL and RfLI and WSP’s SI team.  Drawing on WSP’s global expertise, the team including a Communications Based Train Control (CBTC) expert drafted in from WSP’s Toronto office who played a key role in debugging the all-important signalling software. 

Co-located with the client, this +20-team added a much-needed continuity to technical planning and coordination, including testing and commissioning, assurance, technical issues and all operational mitigations and restrictions.  Through Plateau, every contractor was given clarity as to what they were expected to deliver, when and how. With a robust framework to work from, Crossrail’s contractors were given a renewed sense of purpose, which helped to build trust back into delivering Crossrail.

*Communications Based Train Control (CBTC), European Railway Traffic Management System (including European Train Control System (ETCS), and Train Protection & Warning System (TPWS) (including Automatic Warning System)

Through the operators’ lens

Getting the Elizabeth line into an operable state required a robust and clear strategy demonstrating to the operators and the regulator that the railway was fit for purpose. 

Following consultation with Crossrail and the ultimate operators, MTR and RfLI WSP put in place a three-stage strategy, focusing on operability in terms of design, inspection, and testing and trials. 

By taking on all responsibility for looking at the railway environment from an operator perspective, the WSP team was able to build confidence in the operability of the railway. For example, ’day-in-the-life’ walk-throughs enabled operators and infrastructure managers to consider the experience of those people most affected by the environment. In considering how trains are put into service, for instance, we would imagine the driver's journey, what kind of preparation, route setting and checks they need to accomplish to make this happen. 

One of the biggest challenges we faced was how to work across the multiple contracts that comprised the programme. Our approach to integrating these complex parts was to focus on how elements of the railway, such as the shafts, portals and stations, would be operated on the end-state railway, as opposed to focussing on delivering multiple, overlapping contracts. 

This whole-system view became instrumental in helping the Crossrail project team meet the challenge of testing and commissioning, trial running and in bringing together all the evidence needed to prove that a railway is operable.

Getting Crossrail over the line

Crossrail presented unique challenges. From requiring a new signalling design that would enable all signalling systems to speak with each other, to replacing a disparate contract-focussed approach with a whole-system one; from managing those elements of delivery that had fallen behind schedule, to meeting critical deadlines for testing and commissioning. 

The programme’s eventual success shows what can happen when the client embraces responsibility for and employs a powerful systems integration function, embedded within the client organisation. It starts with a guiding mind – a collaborative approach to problem solving that puts the programme first. Once cooperation and trust have been instilled into a programme, and every activity, milestone and owner clearly defined, no amount of complexity can derail success.

That’s the power of systems integration. 

Did you know?

Almost every function on the Elizabeth line is controlled by computer. Through coordinated software management processes, we identified software configurations for essential functions (e.g. the disturb door function that dictates how a train reacts when the train door is disturbed), which were then factored into the migration plan. We defined every piece of software’s capability to put the overall programme first – software bugs were prioritised and, depending on their significance to programme delivery, either fixed immediately or logged for future releases. To connect all the dots for each issue in this way, required high levels of integration between organisations. 

Discover more about digital transformation in the UK transport sector within our latest insights and trends interactive report, which features Transport for London’s Head of Engineering Rakesh Gaur speaking about how operator feedback was used to tweak the design of the Northern Line extension or Transport for London’s Chief Data Officer Lauren Sager Weinstein explain how anonymised data from customers' smart phones is helping to optimise customer flow and improve passenger experience.