Chilterns Long Tunnel

The UK Government has agreed to extend the High Speed Two (HS2) Chilterns tunnel by 2.6km to address the fears over harm to Chiltren’s Area of Outstanding Natural Beauty (AONB).

The decision follows recommendations by the HS2 Bill Select Committee, a group of MPs that looks into petitions against the project.

Following detailed engineering and environmental assessment, the government has made an amendment to the HS2 Hybrid Bill to extend the deep-bored Chilterns tunnel beyond South Heath.

"These new proposals will protect woodland and mean less disruption for people living nearby."

The extension will avoid the need for a separate ‘green tunnel’ that was planned to be constructed for reducing noise and blending the line into the landscape.

UK Transport Minister Robert Goodwill said: "These new proposals will protect woodland and mean less disruption for people living nearby. It is essential that we take their views into account so that we build this vital railway in the best way possible."

The original design proposed a 13km tunnel, and 12km on two viaducts in two green tunnels. Conservationists have been opposed the proposal as it would harm the protected AONB.

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By GlobalData

A study commissioned by the Chilterns District Council has proposed a long-bored tunnel from under the AONB to protect the landscape, and have a lesser impact on the Misbourne Valley.

However, the committee rejected the proposal in July for the underground tunnel and instead recommended an extension to the originally planned tunnel.

The committee previously said: "On the evidence heard we are strongly of the view that the case for a long tunnel is not made out.
"We believe that the case has been made for an extension of the bored tunnel to the northern end of the South Heath green tunnel. This would not cause an overall delay to the scheme."

The new extension is expected to reduce the scale and duration of construction activity, and also preserve 12 hectares of woodland in Mantle’s Wood, Sibley’s Coppice and Farthings Wood.

Image: The Bill Select Committee recommended the extension in July. Photo: courtesy of