Breakthrough on West London gas tunnel

4 January 2018

Great Britain - A 330m-long tunnel from London’s Chelsea to Battersea Park has broken through. Owned by gas distribution company Cadent, the tunnel forms part of a GBP 1bn programme to replace ageing infrastructure.

Tunnel works, carried out by Barhale and Skanska Civils with support from Mott MacDonald, saw around 4,500m3 of material excavated, which took just over three weeks. The crown was around 26m below ground level and 15m below the river bed as the tunnel traverses the Thames, placing the bore entirely within stiff London Clay.

The machine used was an 1800 Iseki Unclemole TCP machine, which is appropriate for clays and silts while being able to handle cobbles and boulders if encountered. The tunnel was lines with 1,800mm jacking pipes supplied by FP McCann. The geology meant that no other support was needed.

The TBM was controlled remotely by an above ground operator to carve out the 330m long tunnel. “As the tunnel was the deepest pipejack ever attempted under the river Thames, specific measures were put in place to mitigate for the ground conditions and confined environment of working in central London,” says Ovi Frunza, contracts manager for Barhale.