London’s Northolt Tunnels: TBM ‘Anne’ Extraction Complete

Introduction

On Sunday, August 24th, the 9.11m diameter cutterhead of the Tunnel Boring Machine (TBM) known as ‘Anne’ was lifted out of a shaft at Green Park Way in Greenford, west London, after 16 months. The TBM, weighing 1,700 tonnes and stretching approximately 150m, was extracted in sections using a gantry crane.

Tunnel Excavation Completion

‘Anne’ is one of four TBMs that have finished excavating the 8.4-mile-long Northolt tunnels. These tunnels run between West Ruislip and the new station at Old Oak Common.

Tunneling Details

The four TBMs commenced operations from West Ruislip and Old Oak Common, converging in the middle. The machines excavated over 4 million tonnes of London Clay.

Tunnel Wall Construction

During the excavation process, almost 100,000 concrete segments were installed to construct the tunnel walls.

TBM Naming

‘Anne’ is named after Lady Anne Byron, who founded the Ealing Grove School in 1834. The Ealing Grove School was England’s first co-operative school. It provided education for working-class children in west London.

Conclusion

The 9.11m diameter cutterhead of the TBM ‘Anne’ was lifted out of a shaft at Green Park Way in Greenford, west London, after completing the excavation of the 8.4-mile-long Northolt tunnels. The four TBMs excavated more than 4 million tonnes of London Clay and installed almost 100,000 concrete segments.

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Technology

Tunnel Boring Machine (TBM): A machine used to excavate tunnels through a variety of soil and rock strata.