The South Rail Systems Alliance (SRSA) is helping deliver track and rail systems renewals more efficiently through its coordinated, one-team approach.
Amid the current financial climate, the U.K. rail industry is facing an unprecedented challenge: how to build and maintain a network that is resilient, safe and sustainable in the most cost-effective way possible.
As government funding for rail projects competes with other budget priorities, Network Rail (NR) is having to demonstrate that public funds are being well invested – which is why improving efficiency is crucial for its success.
Formed in 2019 between AECOM, Colas and NR, the SRSA is a 10-year framework that harnesses the benefits of collaboration to drive efficiency and tackle these sector challenges head on.
The alliance is accredited to ISO 44001, the international standard for collaborative business relationships. This provides a structured framework that supports joined-up decision-making, strengthens trust between partners and helps deliver more consistent, efficient outcomes across the programme.
A collaborative approach to project delivery
The SRSA is one of three alliances appointed by NR to deliver their £5 billion programme of track and rail systems renewals across three U.K. regions. This collaboration between AECOM, NR and Colas is helping optimise time and cost efficiencies across the Wales and Western Routes and the Anglia Route.
Among many positive outcomes of the alliancing model is better coordination across teams, which means we can resolve challenges – including emergencies and unforeseen circumstances – faster and more effectively.
This approach proved especially valuable during emergency derailment works at locations including London Gateway, Whittlesea, Hoo Junction, Eastleigh and Salisbury. By acting swiftly as a single team, we kept disruption to a minimum and helped services get back up and running sooner – reducing both cost and inconvenience for customers.
Another standout example is the award-winning Westbury South renewal – the largest and most complex track renewal undertaken in Control Period 7 (CP7). Completed in just 30 days, the work avoided six months of disruption, delivered £11 million in savings and future-proofed a key junction for both passengers and freight.
The project was named Project Team of the Year (over £5 million) at the RailStaff Awards, recognising the strength of collaboration, innovation and engineering expertise across the alliance.
This is comfortably the biggest renewal we have planned for the entire control period, and the benefit it brings to the Western Route and the wider Region cannot easily be overstated.
Programme Manager – South Rail Systems Alliance, Network Rail
Progressive assurance: designing with delivery in mind
Another way we’re improving efficiency is through progressive assurance (PA) techniques.
PA brings designers, assurers and builders together for monthly reviews so that any issues or risks that emerge during the design process can be identified and managed from the outset – rather than further down the line.
This ultimately leads to more cost-effective design solutions as it facilitates communication between all parties before the designs are realised.
The benefits of a long-term alliance
Longevity is a key advantage of the 10-year contract. As well as encouraging consistency, a long-term framework helps nurture stronger working relationships and drive continuous improvement via regular reviews.
Thanks to those relationships, we are now involved in the entire lifecycle of the project covering PACE1 to PACE4. PACE (Project Acceleration in a Controlled Environment) is Network Rail’s current framework for managing infrastructure investment projects.
Through this earlier involvement, we have an overview of the entire project lifecycle, which eliminates transfer and handover issues and enables deeper engagement with the work as a result.
To consistently improve efficiency, the SRSA’s benefits are quantified through an efficiency tracker, which measures performance against annual efficiency targets. Using this digital tool, we can monitor efficiency savings and identify where targets weren’t met to enhance forward planning and continue delivering better value for money.
These yearly efficiency Key Result Area (KRA) targets have consistently been achieved and exceeded. They include improvements to design processes and procedures that enable the delivery of higher-quality, more robust design programmes – for example, adopting combined PACE stages as business as usual.
The targets also promote the use of new technology to be used by AECOM and our alliance partners, supporting the delivery of safer outcomes, such as the use of AI‑enabled visual recognition (AIVR) camera surveys, which reduce the need for manual trackside work.
Old Oak Common: an exemplar of digital delivery in rail
Our wider investment in digital delivery has gained industry recognition. For the Old Oak Common Great Western Railway Station Rail Systems project – which will integrate the HS2 and Great Western railway stations – we developed an integrated digital twin to streamline design and coordination.
By using Bentley’s applications, we reduced design time by 30 per cent, cut clashes by 40 per cent and significantly lowered the risk of rework. These innovations are projected to reduce embodied carbon and energy use by up to 20 per cent.
In recognition of this, the project received a prestigious Founders’ Honor at the Bentley Going Digital Awards 2025 and been shortlisted as finalist under the category of Application of Digital Technology Award for the RIA RISE Awards 2026.
Learn more about what makes the Old Oak Common an exemplar project
Why collaboration and efficiency go hand in hand
By working as one integrated team, the SRSA demonstrates how collaboration can translate directly into greater efficiency across the rail sector. Now embarking on our eighth year, the alliance delivered £267 million worth of work in its seventh year, reflecting the maturity, momentum and trust built through long‑term partnership.
This alliance approach enables us to deliver essential renewals more effectively, minimise disruption for passengers and freight, and make better use of public investment. In doing so, we remain closely aligned with NR’s core objective of putting passengers first, while building a safer, more resilient and sustainable railway for the future.