Electricity underwater: Grand Union Canal tunnel provides power boost for HS2

A “micro tunnel” has been dug under the Grand Union Canal in West London at the moment to deliver electricity to HS2’s tunnel boring machines when they start digging the Euston tunnel.

Tunnel shaft (c) UKPN

Tunnel boring machines (TMBs) consume a lot of electricity and often require local power supply upgrades, and UK Power Networks is providing HS2 with 45MVA of electricity supply to facilitate the construction of the high-speed railway.

For comparison, that’s enough electricity to power 11,000 average homes.

The two TBMs are the ones being installed at Old Oak Common later this year and sealed in a box in readiness for digging the tunnel towards Euston station once the government decides if and when it wants to complete the HS2 railway into London as originally planned.

To provide the electricity supply, UK Power Networks and tunnelling specialist Barhale dug a 125 metre long tunnel underneath the Grand Union Canal, starting at the appropriately named Volt Road and reaching the company’s substation on Atlas Road, where HS2 has a large construction site.

Two 6m diameter and 15m deep shafts were constructed before an Akkerman TBM was deployed to drive the tunnel beneath the canal. The 1500mm concrete tunnel was constructed from pipe jacked, pre-cast concrete sections.

Three new high-voltage cable circuits, each around 3km in length, will be energised at the Distribution Network Operator’s nearby substation. These circuits will feed into the network that will power the TBMs.

Pamela Ali, programme manager, Capital Programme at UK Power Networks, said: “It has been a huge achievement to successfully and safely construct the micro-tunnel which will enable to install our circuits across the Grand Union Canal. A huge thank you to the HS2 and the Canal & River Trust for their support throughout.”

Although plans won’t be confirmed until much later, often TBM electricity upgrades are retained later to improve local power supply reliance, and here, the Altas Road construction site will later become a housing estate, so the power supply could be in place before the houses are built.