New photos show inside the huge HS2 shaft under London with tunnelling machines arriving soon

HS2 is preparing for the arrival of huge tunnel boring machines (TBMs) at a site in west London. Two of the huge machines are due to approach the company’s Northolt site from the east, and another two from the west.

One will be at West Ruislip, the other at Victoria Road, near Old Oak Common (OOC). This station will act as HS2’s “temporary terminus” before its Euston leg is completed.

MyLondon took a tour of the site of its ventilation shafts in Northolt, and our reporter was lowered about 40 metres down in a metal box hoisted by a crane. This is called a ‘manrider’.

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Four tunnels will eventually meet at the site. The first TBM is expected to arrive in October or November.

One of the axles is slightly bell-shaped as it is “close” to the existing Network Rail tracks. At its closest point it is just 2.7 metres away.

The eastern tunnel is slightly smaller as trains travel through it, but it will move more slowly than those heading west from London.

Bosses originally thought these tracks could be used by HS2 services. But this would have required the demolition of a lot of existing infrastructure, such as bridges, which would have ‘paralysed West London’.

The axes will prprovide airflow into the HS2 tunnels and let it flow out. The ground at the site is particularly waterlogged and the liquid is having to be pumped.

This is then ‘reloaded’ and placed back into the chalk. Additional pressure caused by these conditions means that a steel ‘can’ is required to receive each TBM.

They are surrounded by reinforced concrete and will continue to be assembled on Sunday 14 July as cranes lift new parts into the shafts. Experts are currently ‘looking at a range of options’ on how the TBMs will be lifted.

All TBMs are expected to be ready by mid-2025. The site also includes cross passages between the underground train tunnels, which would be used by customers in case of an emergency.

There are also shafts for firefighters to descend into. The footprint of the Northolt site is larger now than it will be when the building is complete. Some of the land now occupied by the building will therefore be released back into the market.

It is understood that HS2 currently has Government funding for preparatory work to tunnel from OOC to Euston. TBMs for this are currently being manufactured and will undergo a factory acceptance test. Some parts have already arrived.

Engineers will then install them at the OOC ‘ready to go’ in spring next year. But a funding deal with the Treasury is needed to roll them out to central London.

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