Supporting Network Rail Works
Delivery LNE to Deliver the Nunthorpe Signalling Life Extension
Client: Network Rail Works Delivery
Location: Nunthorpe (ELR: MBW1 3m 35ch to MBW3 30m 69ch)
Sector: Rail Infrastructure – Signalling
Services Provided: Signalling Scheme Development Design, Detailed Design, Technical Assurance and Supporting Consultancy expertise.
Project Duration: July 2023 – May 2026
Overview
Mosaic Rail supported the Nunthorpe Signalling Life Extension Works, a targeted renewal project designed to extend the operational life of signalling assets while maintaining the existing level of safety and functionality.
The Nunthorpe Life Extension Works project was developed to address ageing signalling infrastructure along the Middlesbrough to Whitby line. With core systems dating back to 1985, the scheme was designed to modernise critical assets, ensuring continued safe and reliable operation of passenger services.
This project aimed to replace life-expired equipment with modern equivalent, ensuring continued safe and reliable operation in line with Network Rail’s asset management and renewal strategy.
The Challenge
The ageing and obsolete infrastructure in the Nunthorpe area presented increasing risks to performance and reliability, compounded by the difficulty of sourcing replacement components. The project required considered integration of modern technologies into a live railway environment, alongside managing site-specific constraints.
The challenge was to deliver an upgraded life extension style signalling scheme with an enhanced operational interface while maintaining the existing operating practices and controls present in the area. Maintaining system integrity, safety assurance, and continuity of operations was integral to the requirements for this project.
The delivery of this scheme was extraordinarily complex due to the need to integrate modern signalling, power, and control technologies with legacy mechanical and electronic systems, all within the constraints of a Grade II listed building. The work required careful management of multiple system interfaces (including CBI, level crossings, power supplies, and track circuits), staged migration from existing to new assets without disrupting operations, and coordination across diverse disciplines—while maintaining safety, reliability, and compliance throughout.
- Recovery of the existing lever frame and provision of an NX Control Panel and level crossing control pedestal; working with our client within the constraints of grade II listed building consents.
- Renewal of No Signaller Key Token (NSKT) equipment and working, with consideration to the existing auto route setting circuitry;
Interface with CBI technology and provision of directional controls to facilitate single line working; - Replacement of existing SB lever frame interlocking wiring with free wired interlocking circuitry housed in a new REB;
- Replacement of the existing gate wheel controlled level crossing, with power operated sliding barriers integrated with Typical MCB level crossing control circuitry.
- Integration with DCP supplier for provision of upgraded signalling power supplies with UPS, to provide a robust and reliable power architecture throughout the area;
- Conversion of existing Low Power DC track circuits to Medium Voltage DC track circuits and associated recovery of local battery supplies;
- Provision of RCM and busbar monitoring throughout the area of renewal;
- Conversion of two point ends to clamplock style machines commensurate with the recovery of the mechanical signalling.
- Recovery of existing semaphore signals and replacement with Dorman LED iLS and CLS type signals to offer savings and improvements in maintainability;
- Provision of AWS for all new signals within the Nunthorpe control area.
Our Approach
Mosaic Rail’s signalling design team delivered the full ES4-ES8 design stages in accordance with Railway Group, Rail Industry and Network Rail Standards.
We collaborated closely with Network Rails Engineering, Construction and Test teams including DCP, Civils and the POSB sub-contract teams. This collaborative approach ensured the completion of robust, integrated and compliant engineering details, that paid cognisance to site requirements for buildability and maintainability.
This ultimately ensured a successful and on time commissioning.
Our approach included:
- Detailed assessment of existing and proposed signalling principles and assets, correlation of Signalling records and resolution of legacy discrepancies.
- Integration with overlapping work programmes to ensure safe integration and controlled amendments to the infrastructure.
- Production of comprehensive design deliverables covering scheme plans, control tables, location area plans, control panel design, power calculations and MCB level crossing design.
- Integration of safety, environmental, and occupational design requirements to ensure full compliance with CDM and CSM obligations.
- Active participation in Interdisciplinary Checks (IDC/IDR) and Design Gateway Reviews with Network Rail, and the Route Engineering team including Level Crossing Managers.
The Solution
Mosaic Rail successfully delivered detailed signalling design solutions that supported Network Rail in renewing the following assets in the Nunthorpe Area:
The scheme delivered a comprehensive modernisation of signalling and power systems. Key interventions included the design of a new Type A Relocatable Equipment Building (REB), design of an NX control panel and conversion of LVDC track circuits to modern MVDC complete with RCM technology supported by a UPS-backed power supply.
Signalling upgrades replaced mechanical signalling assets with modern solutions including replacing semaphore signals with Dorman LED iLS and CLS type signals, while level crossing improvements introduced a trial Power Operated Sliding Barrier (POSB), enhancing safety for both rail users and the public. Additional works included the provision of clamp lock style power-operated points, upgraded monitoring systems, provision of AWS and Track Circuit upgrades.
New and re-used equipment was type-approved with the exception of the Power Operated Sliding Barrier which is currently under trail, compliant with Network Rail standards therefore ensuring a consistent, maintainable, and safe installation.
Key Outcomes:
- Improved safety and reliability across the route
- Delivered ES4 -ES8 design and assurance to programme and quality standards.
- Reduced long-term maintenance costs and risk of asset failure.
- Strengthened client confidence through clear communication and design governance.
- Successful delivery of innovative solutions under controlled trial conditions
- Enhanced maintainability through modern, standardised equipment
Results & Impact
Through meticulous design and collaborative delivery, Mosaic Rail supported Network Rail to achieve a seamless transition from ageing legacy equipment to a modern, maintainable solution aligned with operational requirements.
The project has significantly enhanced the reliability and safety of the Nunthorpe control area. Modern equipment and improved system monitoring have reduced maintenance risks and increased operational resilience. Importantly, the phased delivery approach ensured continuity of passenger services throughout the programme.
Key Takeaways
This project demonstrates the value of proactive asset management and phased delivery in complex rail environments. It highlights how modern standards can be effectively integrated with legacy systems through a pragmatic, risk-based approach, while maintaining safety, performance, and operational continuity.
- Targeted renewals can deliver significant asset life extension without operational disruption.
- Close collaboration between design, construction, and Network Rail assurance teams accelerates safe delivery.
- Mosaic Rail’s flexible delivery model supports Network Rail with agile, high-quality signalling expertise.
Partner with Mosaic Rail for signalling design and assurance services that extend asset life, improve safety, and optimise renewals across the UK rail network.
