HS2 has reached a major milestone with the launch of its final tunnel boring machine (TBM), marking another step forward for the high-speed railway linking London and the West Midlands.

On 16 March, the last of 11 tunnel boring machines began its journey from Old Oak Common towards Euston, excavating the second bore of the 4.5-mile Euston Tunnel.

The machine, named ‘Karen’ after pioneering British train driver Karen Harrison, continues the tradition of naming tunnelling machines after notable women.

To celebrate the launch, two drivers from Avanti West Coast, Hayley Richardson and Vicky Knight, joined engineers on site and were given the chance to help operate the machine.

The launch follows the start of tunnelling by the tunnel boring machine ‘Madeleine’ earlier this year. Together, the two machines will complete the twin-bore tunnel, a key section that will bring high-speed services directly into central London, boosting capacity and improving reliability for passengers.

This milestone comes as HS2 undergoes a major programme reset under chief executive Mark Wild, aimed at refining construction sequencing and providing greater certainty on costs and delivery times.

The 198-metre-long tunnel boring machine operates continuously, excavating soil while installing concrete segments to form the tunnel lining. Across both bores, more than 48,000 segments will be installed, with around 1.5 million tonnes of material removed and transported for reuse elsewhere in the UK.

The Euston Tunnel is one of several on the route, with others including the Northolt and Chiltern tunnels already completed, as HS2 continues to take shape.

Once complete, the new station at Euston is expected to play a significant role in the regeneration of the surrounding area, supporting new homes, jobs and investment.

“It is a fantastic privilege to be part of this latest milestone for HS2   – it’s not every day you get to swap a train cab for the controls of a tunnelling machine.

“For it to be named Karen is a wonderful tribute to a pioneering woman who helped pave the way for female drivers today.”

Hayley, Train Driver.

“Karen Harrison’s story is one to admire, and it is great she is getting the recognition she deserves for the influential role she played in shaping our industry.

“I’m honoured to take part in this event to celebrate her legacy, as well as mark another key moment in building the railway of the future.”

Vicky, Train Driver.