Connecting tunnels 20m underground

Battersea Power Station stopped generating electricity in 1983 and a new electricity substation is being built to help distribute power to homes and businesses across the new neighbourhood. The substation will connect to the existing electricity network via the Battersea Cable Tunnel.

To reduce noise and disturbance during the tunnelling works, the site was set up within an existing warehouse. During conversion of the warehouse and installation of a Gantry Crane, a 30m deep, 7.5m diameter access shaft and sprayed concrete lining (SCL) launch tunnel were constructed on the substation site in Battersea, so that a Tunnel Boring Machine (TBM) could be used to construct the new 300m long cable tunnel.

The key project risk was in connecting the new 300m long cable tunnel to the existing wedge-block tunnel. The TBM stopped 4m away from the existing tunnel, where it was disassembled, leaving only the open-face shield in place.

A connection was then formed by hand mining and constructing a reinforced concrete cast in situ chamber around the existing tunnel and removing selected rings.

COWI was the contractor's permanent and temporary works designers for the project.

In 2018 the tunnel project was named Best Infrastructure Project at the ICE London Awards