HS2 reveals significant progress of the new tunnel at Euston station

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HS2’s station contractor, Mace Dragados JV (MDjv), creates space by excavating a 20-metre deep ‘box’ home to a new Traction Substation.

A Traction Substation (TSS) converts electrical power to a form suitable for a rail system. This TSS will enable the relocation of equipment needed to provide services and ventilation for the safe operation of the Northern Line at Euston.

Connecting this highly-secure new Traction Substation – dubbed the ‘sugar cube’ due to its eye-catching white tiled exterior – to the London Underground network is a 90-metre long – as long as the Statue of Liberty laid down – 6.5-metre wide tunnel running under the HS2 construction site.

The work to construct the tunnel took 16 months, and the MDJV team sank a 20-metre deep shaft before carving out the underground passage and coating it with a primary sprayed concrete lining (SCL). After applying waterproofing, the team reinforced the tunnel with steel and concrete to give it the strength and structure needed ahead of the construction of the HS2 Station that will be taking place above it.

MDjv, supported by its principal sub-contractors, Cementation Skanska, Careys and JGL, brought forward innovations to improve the environmental credentials of the works. Redesigning the tunnel to lower the carbon impact during construction – through reduced material and water use, a reduction in vehicle movements, and lower energy consumption – resulted in an overall carbon saving of 140 tonnes. In comparison, efforts to reuse material already on site resulted in over 1,000 fewer lorry movements and an associated saving of 76 tonnes of carbon dioxide from vehicle emissions.

Throughout the tunnelling works, the shaft has been enclosed by an acoustic shed designed to reduce noise impact on the community and businesses nearby. This enabled 24-hour working, which was required to meet the programme’s demands.

With the tunnelling and excavation works at the site now complete, the team will be working to construct the below and above-ground structures for the new Traction Substation before fitting it out with the necessary equipment and connecting it to the Northern line. The building will have three storeys below ground and four above.

Once the new structure is complete, the existing TSS on Melton Street will be demolished. The building, which opened in 1907, was once an entrance and exit to what Londoner’s now known as the Northern line and was designed by the Architect Leslie Green. In 1914 changes to the Underground at Euston meant that the building was no longer used as a ticket office and entrance but was used to house ventilation equipment for the underground. HS2 will carefully remove some iconic historical features and tiles, donating these for reuse and heritage displays.

Source: © High Speed Two Ltd 2022

Image source: © High Speed Two Ltd 2022

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