HS2: Micro power tunnel completed in West London

UK Power Networks and Barhale have built a micro power tunnel under the Grand Union Canal in West London to enable High Speed 2 (HS2) future construction activities.

The 125m long tunnel runs beneath the Grand Union Canal to a substation on Atlas Road.

Civil engineering, infrastructure and tunnelling specialist Barhale was appointed by UK Power to bore the tunnel. It will be used to carry power cables for HS2’s tunnel boring machines (TBMs) that are expected to excavate the planned high-speed rail tunnels from Old Oak Common to Euston.

Three new high voltage cable circuits around 3km in length will be connected to UK Power Networks’ nearby substation, which feed into the network that will power the manned TBMs.

UK Power Networks is providing HS2 with 45MVA of electricity supply to enable the construction of the high-speed railway.

Launch and reception shafts measuring 6m in diameter and 15m in depth were constructed to enable the Akkerman TBM to launch and excavate the 120m long tunnel beneath the canal.

The tunnel was constructed from pipe jacked, pre-cast concrete sections.

Barhale’s regional manager Ovi Frunza said the microtunnelling project was “another key piece in the HS2 jigsaw”.

He added: “We are pleased to be able to continue to play our part in the continuing construction of HS2. We are involved in works at several sites along the route, including essential diversionary work at Ruislip and enabling works at the London terminus.”

Barhale has said that the completion of the micro tunnel is a “significant milestone” for UK Power Networks and HS2 as it enables the final section of the 33,000V cable route to be completed.

HS2 head of utilities Niki French said: “The delivery of this power tunnel is a critical part of our programme to build the new high-speed railway into the heart of London.  Through close collaboration and great teamwork, we have worked together to ensure the HS2 programme is maintained.”

UK Power Networks capital programme manager Pamela Ali 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.”

HS2’s London tunnels contractor is the Skanska Costain Strabag joint venture (SCS JV).

SCS Utilities’ Jaione Echeveste said: “HS2, UK Power Networks and their contractors have been working collaboratively and relentlessly with key stakeholders to design and deliver this scheme.

“The commitment and responsibility demonstrated by all parties throughout the project have stood out which have allowed us to achieve successfully this critical outcome.”

The completion of the micro power tunnel comes a couple of months after the Atlas Road logistics tunnel was completed.

In January this year, a TBM broke through into Old Oak Common station to complete the 853m long logistics tunnel, which runs from Old Oak Common station site to HS2’s Atlas Road logistics hub.

The tunnel will be used to transport materials required for the construction of the planned Euston tunnel.

Later this year, the SCS JV plans to lower two additional TBMs into the Old Oak Common station box, which is currently under construction by a separate joint venture – Balfour Beatty Vinci Systra (BBVS JV). The team is planning to assemble and bury the two TBMs beneath Old Oak Common, so that they can commence with boring the Euston tunnel once the government gives the green light. The two TBMs that will drive towards Euston weigh over 2,000t and measure 140m in length.

Construction work on the 7.2km long tunnel between Old Oak Common and Euston station was pushed back when the government announced its decision to delay delivery of Euston station.

Following the government’s decision in October last year to axe the northern leg of HS2 from Birmingham to Manchester, private investment is now also expected to help fund delivery of Euston station.


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