North Downs Line

on this page

Markets

Transportation
Services

Consulting, strategy & advisory

Project & program management
Location

South East of England, UK
Client

Network Rail
Completion date

September 2025

Gabriel Azevedo

Senior Project Manager, London, United Kingdom contact form

Delivering safer, smarter and more reliable rail infrastructure for the South East

The North Downs Line (NDL) Project represents a critical infrastructure upgrade for Network Rail across a strategically important railway corridor in the South East of England, running between Guildford and Gatwick Airport.

Faced with ageing infrastructure and growing safety concerns along this busy mixed‑use route, Network Rail commissioned a programme to renew level crossings and upgrade signalling – strengthening safety, reliability and operational efficiency for both passengers and local communities. AtkinsRéalis was commissioned to deliver a comprehensive upgrade of four level crossings, bringing them up to current safety standards, reducing incident risk, and replacing ageing signalling infrastructure with its Advanced Signalling Method solution.

Early engagement and assessments

As AtkinsRéalis began its initial assessment, working closely with Network Rail to understand both immediate risks and long‑term operational challenges, it became clear that a targeted upgrade would not be enough. Large portions of the line relied on signalling technology and trackside equipment dating back to the 1960s and 70s, a large portion of which had begun to degrade. Instances of failure placed increasing pressure on maintenance teams and contributed to risks of delays and disruption. Adding to these challenges, sourcing spare parts for such old equipment had become increasingly difficult, making long‑term maintenance unsustainable.

A further, urgent driver was safety, with three of the four level crossings in scope among the least safe in the southern region. By taking collective ownership of the safety challenge, AtkinsRéalis and Network Rail aligned early on a solution that addressed not only current risk, but future performance. Network Rail’s modelling predicted that upgrading these crossings would reduce safety incidents by approximately 97%, making the modernisation not only operationally essential but critical for safeguarding users.

Scope and technical modernisation

AtkinsRéalis deployed its Advanced Signalling Method (ASM) solution – an end‑to‑end integrated approach built on assured design templates and strengthened with new innovations developed specifically for NDL. This included:

Two MCB CCTV crossings
Two AtkinsRéalis first-of-type MCB Obstacle Detection (OD) MK2 systems, allowing autonomous obstacle detection without constant signaller monitoring
A new ElectroLogIXS interlocking system, controlled from Guildford Signal Box
Upgraded axle counter sections enabling improved headways and future timetable enhancements
A design that future proofs the railway that would allow for additional services to run per hour

NDL became a proving ground for several enhancements now being rolled out across other programmes:

Panel Processor enabling modern and legacy systems to interface seamlessly
Relocatable Equipment Buildings (REBs) integrated into ASM for the first time
Scalable Remote Condition Monitoring (SRCM) supporting proactive maintenance
'Basket of Goods' logistics system, streamlining procurement and reducing on‑site risks
Fully integrated off-site testing of all the crossings, reducing construction and testing time on site
‘Digital-first' methodology ensuring efficient, high-quality fully coordinated delivery, with digital twins enabling 3D design and Virtual Reality review within our in-office ‘Lava Lab’

Photo of our offsite testing facility with test level crossing barriers

Innovations that drive efficiency

As part of the North Downs Line project, AtkinsRéalis introduced full off‑site integrated testing – an approach used for the first time on any project of this kind. Entire level‑crossing systems were assembled, integrated and tested in advance at our dedicated facility in Crewe, enabling engineers to validate every component under controlled conditions before any equipment reached the railway.
By completing this work off‑site, we significantly reduced the time teams needed to spend in the high‑risk trackside environment, lowering exposure and improving overall safety. This method also helped identify and resolve issues long before installation, preventing on‑site complications and streamlining commissioning activities. As a result, the project achieved an exceptionally high standard of quality – commissioning with only 12 deferred test logs across the entire project, a figure well below typical industry benchmarks.

Commissioning the North Downs Line upgrade brought together more than 400 staff from 37 organisations, making early integration essential. A strong, collaborative team culture enabled faster decision‑making, shared planning and efficient sequencing of works, helping issues to be resolved before they reached site. This coordinated approach avoided 10 days of disruptive access and supported a smoother, more efficient post‑commissioning setup of the Obstacle Detection systems. Taking an end‑to‑end approach, AtkinsRéalis worked across disciplines and delivery partners to manage interfaces effectively, reduce delivery risk and ensure clear accountability throughout the programme.

These innovations, developed through NDL, are now part of our standardised testing approach and are being mandated and deployed across subsequent projects including Sizewell C. This refined ASM delivery process demonstrates not only the effectiveness of the approach, but its exportability, repeatability and long‑term value for clients delivering complex rail infrastructure at scale.

Image showing Brook level crossing with barriers raised

Protecting place and supporting communities

Delivering construction within an Area of Outstanding Natural Beauty brought environmental constraints and restrictions on road closures. Public consultation and multi-agency coordination were essential. AtkinsRéalis worked closely with Surrey County Council, Network Rail, local authorities, and communities to minimise disruption. Great lengths were taken to ensure that road closures were carefully planned and staggered, preventing significant levels of disruption and diversions.
To mitigate these impacts, AtkinsRéalis introduced practical community support measures, including arrangement of DIA compliant minibuses to safely transport residents across affected areas during construction, including provision for local school runs. Extensive engagement and proactive communication ensured that community needs were respected throughout the works.

A safer, more reliable route

The upgrade of the North Downs Line shows how innovative signalling upgrades, safer level crossing solutions and collaborative delivery can transform a critical UK rail corridor. By combining off‑site testing, digital systems and a partnership‑led approach, AtkinsRéalis helped Network Rail deliver a faster, safer and more reliable railway.

By taking shared ownership of the challenge and delivering as a true delivery partner, AtkinsRéalis helped Network Rail implement a compliant, sustainable solution that meets today’s needs and supports the future of the route.

97 %

reduction in safety incidents

20 %

reduction in engineering delivery timescales

18 %

fewer railway environment activities

12 %

reduction in maintainable lineside infrastructure

Downloads

View all downloads

Trade releases

View all trade releases