Thames Tideway Tunnel: Beneath the Thames Tunnelling Challenges and Achievements
This paper examines the engineering strategies and lessons from the construction of the Thames Tideway Tunnel, London’s flagship ‘super sewer’. Spanning 25 km beneath the River Thames, the project tackled exceptional technical challenges including high-pressure hyperbaric interventions, hypoxic ground gas, and complex third-party asset interfaces. Using a combination of Earth Pressure Balance and slurry TBMs, works progressed through variable geology across the London Basin, requiring bespoke machine specifications, geotechnical risk mitigation and continuous monitoring.
Key innovations included the ‘turn and bury’ method for TBM retrieval, the UK’s first use of mixed-gas hyperbaric training, and the successful tunnelling beneath sensitive heritage structures like Tower Bridge and Hammersmith Bridge. A collaborative contracting model facilitated integrated delivery across contractors and designers. Sustainability was a central consideration, with 100% of spoil and precast segments moved by river, significantly reducing HGV traffic and carbon emissions. Despite Covid-19 disruptions, the tunnel drives were completed by 2022 with minimal delay and no major incidents, establishing a foundation for improved water quality and environmental resilience in London.
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This paper appeared in the Proceedings of the Institution of Civil Engineers – Civil Engineering, the flagship journal of the Institution of Civil Engineers, published by Emerald Publishing Limited.
Image credit: Tideway