A huge new 8.4-mile-long UK tunnel has been completed, with HS2 project managers hailing the project as a major milestone. At a time when the cost of the railway has come under renewed scrutiny after it emerged that costs had soared by £37billion, bosses are celebrating crossing the finishing line on this particular part of the mammoth build. The Northolt Tunnel is HS2’s second longest, stretching between West Ruislip and the new railway interchange at Old Oak Common in London, and will eventually have trains passing through travelling between the capital and Birmingham.

The fourth of four tunnel boring machines (TBMs) being used to dig the twin tunnel – the second-longest on the HS2 route between London and the West Midlands – finished its work on June 26. Alan Morris, Construction Delivery Director, HS2 Ltd, said: “Completing the excavation of this 8.4 mile-long tunnel on HS2 is a real achievement and one the team should be immensely proud of.

The Transport Secretary has said there must be a ‘line in the sand’ as regards HS2. (Image: Getty)

“We’re building HS2 for the future, to increase capacity on our rail network and improve journeys for millions of rail users.

“The construction of HS2 is already bringing benefits, with £20billion economic benefit already being delivered at either end of the line.”

Earlier this month, the Transport Secretary, Heidi Alexander, announced that she would accept all recommendations from the James Stewart review – including stricter cost control measures, the delivery of the network’s new Euston station, stronger ministerial oversight and accountability and a new governance structure with a shareholder board, a programme board with independent members, and specialist sub-boards – to address “years of mismanagement” and “restore public trust” in HS2.

Tunnel boring machines have completed their work on the Northolt Tunnel. (Image: HS2)

Ms Alexander said: “This must be a line in the sand. This government is delivering HS2 from Birmingham to London after years of mismanagement, flawed reporting and ineffective oversight.

“Mark Wild and Mike Brown were part of the team, with me, that turned Crossrail into the Elizabeth Line – we have done it before, we will do it again.

“Passengers and taxpayers deserve new railways the country can be proud of and the work to get HS2 back on track is firmly underway.”