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Delivering Fibre Optic Connectivity for the Thames Tideway Tunnel

The Thames Tideway Tunnel, also called London’s Super Sewer, is the largest infrastructure project ever undertaken to improve the health of the River Thames and modernise the capital’s Victorian-era sewer system. The 25 km tunnel, stretching from Acton in west London to Abbey Mills in the east, links to Beckton Sewage Treatment Works.

Designed at 7.2 metres in diameter and up to 67 metres deep, the tunnel intercepts 34 sewer overflows and provides 1.6 million cubic metres of storage, reducing raw sewage discharge into the Thames from approximately 18 million m³ annually to just 2.4 million m³.

Mission-critical robust fibre optic connectivity, enabling precision GPS tracking, telemetry data collection, and maintaining communications and safety systems.

Client:

Sector: Civil Engineering

Project Type: Fibre Optic Network

Requirements: Installation of a robust, high-capacity fibre optic network that could perform under uniquely difficult tunnelling conditions, for multi-bore GPS & communication with telemetry and data collection intergration.

The ambitious engineering programme required six Tunnel Boring Machines (TBMs) – including the largest named Millicent and Ursula, with diameters of up to 8.84m – that continuously excavated and installed reinforced linings beneath central London.

For the TBMs and supporting operations, robust fibre optic connectivity was mission-critical, enabling precision GPS tracking, telemetry data collection, and maintaining communications and safety systems for workers operating up to 65 metres underground. ACCL was entrusted to provide the data cabling infrastructure for these functions.

Photo credit: Thames tideaway

Project Scope

To design and install a robust, high-capacity fibre optic network that could perform under uniquely difficult tunnelling conditions. The scope included:

  • Fibre Optic Backbone Network

Deployment of approximately 30 km of ruggedised Excel 16-core single-mode fibre optic cabling, installed in 500-metre sections along the tunnel route.

Fibre links ran from surface shafts down into the tunnel environment, with spliced interconnections to create an uninterrupted data network.

  • Data Collection & Telemetry Integration

Establishing permanent fibre links between the bore machines (moles) and surface control systems for real-time telemetry data.

Monitoring included bore head position, machine strain, pressure levels, and environmental conditions.

  • GPS & Worker Communications

Fibre-fed GPS positioning systems ensured accurate boring alignment across 25 km of London subsoil.

Connectivity supported Comms equipment for safe working in the tunnel, enabling reliable voice and safety alerts between crews underground and above ground.

  • Instrumentation & Monitoring Applications

Fibre optic cables were used to monitor strain, and ground movements. during construction – the fibre solution’s intrinsic safety (no electrical charge) made it ideally suited for this high-risk environment.

0333 900 0101 sales@network-data-cabling.co.uk Contact us

ACCLs Solution

Results

  • Installed over 30 km of high-specification fibre optic backbone inside a constrained and hostile tunnelling environment.
  • Established resilient 500-metre data collection nodes, ensuring precision telemetry from each TBM.
  • Delivered seamless GPS integration, critical for aligning six TBMs boring simultaneously at depths of 35–65m.
  • Enabled constant worker communications, meeting strict health and safety requirements across a multi-year, multi-shaft civil engineering programme.
  • Provided structural monitoring data in real time, helping engineers manage ground movement risk and maintain the stability of London’s surrounding infrastructure during contstruction.
Photo credit: Thames tideaway

Project Success

  • Engineering in challenging environments: Fibre optic cabling was installed in deep, confined, and often wet conditions – requiring innovation in routing, ruggedised materials, and meticulous handling.
  • Critical safety contribution: Reliable communication networks underpinned site-wide health and safety compliance, ensuring safe worker coordination during tunnelling operations.
  • Innovative fibre applications: Using fibre not only for telecoms and data but also as an intrinsic part of structural health monitoring systems.
  • Scalability and resilience: The distributed fibre network architecture allowed expansion, redundancy, and robust performance over many years of active construction.

ACCL’s work helped ensure that the Tideway Tunnel’s enormous engineering effort could be delivered with precision, safety, and resilience.

0333 900 0101 sales@network-data-cabling.co.uk Contact us

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We undertand that connectivity is critical when working at scale in hostile environments. Robust and verstile communications networks that have multiple functions is vital for health and safety, ground monitoring, precision equipment and data collection.

 

0333 900 0101 sales@network-data-cabling.co.uk Contact us