Axle Counter Overlay: Building Train Detection Resilience into the Thameslink Core between Blackfriars and Farringdon
Our client: Amaro Group.
Project overview
Within the southern section of the Thameslink Core, the project aims to mitigate the operational impact of track circuit failures by providing a secondary train detection system. The overall project involves an axle counter overlay using Frauscher axle counters and associated hardware and software, intended to provide continuous train detection during failures of the existing primary track circuit infrastructure.
Our scope is a package of works covering the telecoms elements of the project. This runs from the bespoke design, installation and testing of the Fibre Optic infrastructure, Cisco network switches and the provision of a Network Time Server for the network, through to hand back and entry into service. Equipment is integrated within existing Signalling Equipment Rooms (SERs) and Relocatable Equipment Buildings (REBs), alongside associated lineside equipment locations.
This is a practical example of adding resilience to existing railway infrastructure: introducing a secondary detection layer while working within established operational environments.
The challenge: managing the impact of track circuit failures
Track circuits are part of the primary train detection infrastructure on the railway. When a track circuit fails, the ability to detect trains using that equipment can be affected, with potential consequences for operations and service continuity.
The impact can be particularly significant on a busy commuter route. When train detection is disrupted, services may need to be managed differently while the issue is investigated and resolved. The response depends on the circumstances and the operational arrangements in place; the aim of this project is to reduce the impact of failures in the existing primary detection system by providing a secondary means of detection.
The challenge is not simply to introduce additional equipment. An overlay must be designed and integrated with existing infrastructure, including equipment housed in SERs and REBs and equipment located alongside the track. Each element needs to form part of a coherent system that can be tested and commissioned as a whole.
The solution: a Frauscher axle counter overlay
The proposed solution is an axle counter overlay system using Frauscher axle counters and associated hardware and software. It will act as a secondary train detection system alongside the existing primary track circuit infrastructure.
In general terms, axle counters use sensors at defined points on the railway to detect passing wheelsets. The system processes these detections to provide train presence information for the relevant section. Frauscher describes its axle counting systems as combining wheel sensors, evaluation equipment and interfaces to support track vacancy detection. More information is available on Frauscher’s axle counter technology.
For this project, the important principle is that the overlay provides an additional train detection layer. During failures of the existing track circuits, the project aims to enable continuous train detection through the axle counter system. The overlay is intended to complement the primary infrastructure, rather than replace it.
Integrating with existing railway infrastructure
Introducing a secondary system in an established railway environment calls for careful attention to where equipment is installed and how the system is brought together. The project scope includes integration within existing Signalling Equipment Rooms and Relocatable Equipment Buildings, as well as associated lineside equipment locations.
SERs and REBs provide locations for railway equipment and systems. Lineside locations, meanwhile, require equipment to be installed in the railway environment alongside the track. The design and installation work must take account of these different settings and the interfaces between equipment locations.
Figure 1: An image from one of the REBs part way through the installation phase.
This kind of integration is a familiar consideration across railway infrastructure projects. Designs must be clear and deliverable, installation must follow the agreed requirements, and testing must confirm that the relevant equipment and system functions operate as intended. Careful coordination across each stage supports a controlled route from engineering design through to commissioning.
Our role across the project lifecycle
Our package of works covers the telecoms elements of the project: bespoke design, installation, testing and commissioning of the fibre optic infrastructure, Cisco network switches and the Network Time Server, together with hand back and entry into service. These stages are connected, with decisions made during design informing the installation approach and the subsequent test and commissioning activities.
Design
We provide the bespoke design for the fibre optic infrastructure that underpins the axle counter overlay network, including the Cisco network switches and the Network Time Server provision. The design takes account of the project requirement to integrate with existing SERs, REBs and lineside locations. Clear, coordinated design is an important foundation for reliable installation and system integration.
Our railway design services support projects from design development through to detailed engineering. For this project, design is focused on the telecoms infrastructure the overlay depends on and the railway environment it must interface with.
Installation
Our installation scope covers the deployment of the fibre optic infrastructure, Cisco network switches and the Network Time Server across the relevant indoor and lineside locations. This includes work associated with the existing SERs and REBs, as well as associated equipment locations beside the railway.
Railway infrastructure installation requires a disciplined approach to working within existing environments. The planned equipment, its interfaces and the installation requirements need to be considered together so the physical build supports the intended system arrangement.
Testing and commissioning
Testing and commissioning rail telecoms systems is essential to confirming that installed equipment and system functions meet the project requirements before the system is brought into operation. Our scope includes testing of the fibre optic infrastructure, the Cisco network switches and the Network Time Server arrangement supporting the overlay.
Figure 2: An image from one of the REBs part way through the Ethernet Services testing phase.
Our installation, testing and commissioning services bring these activities together, with testing and documentation forming part of a structured engineering process. The specific test activities for this project are governed by the applicable project requirements and approved arrangements.
Hand back and entry into service
Our scope runs through to hand back and entry into service. That means the telecoms infrastructure is not simply installed and tested: it is documented, demonstrated against the project requirements and formally transitioned so the overlay can be brought into operational use.
Project delivery
Coordinating design, installation, testing, commissioning and hand back is central to successful rail project delivery. Our project delivery services support the management of engineering work across the project lifecycle, with a focus on safe, coordinated and reliable delivery.
Across the Thameslink Core project, our role is to deliver the telecoms elements that support the secondary detection system through these connected stages. The focus remains on the specified scope and integration requirements, without overstating outcomes beyond those available for reporting.
Building resilience through a considered overlay
The Thameslink Core axle counter overlay project addresses a clear engineering objective: mitigate the operational impact of track circuit failures within the southern section by providing secondary train detection. Frauscher axle counter technology, integrated into existing equipment rooms and lineside locations, forms the basis of the proposed solution.
Our work spans the telecoms package that supports it: bespoke design, installation and testing of the fibre optic infrastructure, Cisco network switches and the Network Time Server, through to hand back and entry into service. By approaching these activities as part of one connected scope, we support the integration of a secondary train detection system into established railway infrastructure.
For network operators, infrastructure managers and principal contractors, projects of this kind demonstrate how rail network solutions can be developed around existing systems and operational needs. We look forward to continuing to support reliable railway infrastructure through coordinated engineering and project delivery.