Go to content

Buckinghamshire tunnels

An aerial CGI image of the railway in a landscaped cutting approaching the Chilterns tunnel.
The approach cutting to the Chilterns tunnel.

The Chilterns tunnel

The Chilterns tunnel is the longest tunnel on the route. The twin-bore tunnel is 10 miles long and will carry passengers under the Chiltern Hills. Two tunnel boring machines, Florence and Cecilia, will be used on this part of the route.

The two enormous 2,000 tonne machines – named Florence and Cecilia – have been meticulously reassembled, tested and commissioned, by an expert team of tunnelling engineers, before they start work on the high speed rail project’s first tunnels.

TBM Florence was launched in May 2021 from Chiltern tunnel’s South Portal site next to the M25 in Buckinghamshire.

Find out more about the launch

The 10-mile-long ‘twin bore’ Chiltern tunnel will be the longest on the project, the first to start construction, with the TBMs set to be underground, working 24/7 for more than three years.

Chilterns tunnel location map

After construction of the tunnel has been completed, we will reuse construction materials to create 127 hectares of new chalk grassland, woodland, wood pasture and wetland habitats that will substantially enhance the local natural environment

The Colne Valley Western Slopes project

Nine apprentices will play a part in the monumental programme of work to dig the 10 mile twin bore tunnels under the Chilterns. The development programme will enable apprentices to learn from, and work with, the experts who will manage the logistics of the 3.5 year-long tunnelling operation.

Find out more about the tunnelling operative apprenticeships

Find out more about the Chiltern tunnel in Buckinghamshire

Find out more about Chiltern tunnel

Tunnelling under the Chiltern Hills

Watch to find our more about the 10 mile tunnel.

The Wendover tunnel

Wendover tunnel is a green tunnel is a tunnel located to the west of Wendover just under one mile in length. This is a ‘cut and cover’ tunnel meaning that a cutting is created in the ground, a tunnel ‘box’ is constructed within the cutting and then the space around the box is filled to create an area of land on the surface.

Wendover tunnel location map