The first of five headhouses that will provide ventilation and emergency access to the 16km (10-mile) Chiltern tunnel has obtained planning approval from Buckinghamshire Council.

The Chalfont St Peter headhouse has been designed to look like one of the barns that is typical of the area to allow it to blend in with its environment.

The single-storey building will feature a grey zinc roof, while the doors and vent openings will be a dark bronze colour. The whole structure will sit on a dark blue brick base.

Chiltern tunnel vent shaft headhouse at Chalfont St Peter

© HS2 Ltd

Below ground, the 78m ventilation shaft will reach down to the twin tunnels below. Fans and other equipment to regulate air quality and temperature and remove smoke in the event of fire will be installed in these shafts.

From a landscaping perspective, the site will be given new trees and hedgerows to act as a screen, while existing mature trees around the boundary will be retained as far as possible.
source= https://railway-news.com/hs2-chiltern-tunnel-vent-shaft-given-planning-approval/