The design of the vent shaft headhouse that HS2 plans to build at Little Missenden, to provide ventilation and emergency access to the 10-mile-long Chilterns tunnel, is similar in style to the HS2 headhouse at Chalfont St Peter announced earlier this year.
One of four headhouses that will be built above vent shafts leading down to the railway tunnel below, it will be set back from the main A413 trunk road.
The single storey design is inspired by barns and historic agricultural buildings found in the surrounding area. This has influenced the building’s dark and neutral colours, which are designed to fit into the surrounding landscape and to weather naturally over time.
The landscaping around the headhouse, for which designers took inspiration from the surrounding natural environment including native trees and chalk grasslands, has been designed to screen the building through planting and blending it into the landscape.
The Little Missenden headhouse will sit atop a 17.4-metre-diameter, 30-metre-deep ventilation shaft that will reach down to the railway’s twin tunnels below. It will contain fans and other equipment designed to regulate air quality and temperature in the tunnels, remove smoke in the event of a fire and provide access for the emergency services.
In addition to the headhouse, the site will include an autotransformer electricity station and a stair and vent building, both of which carry similar design cues.
The plans have been drawn up by HS2’s main works contractor Align JV – a team made up of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.
Daniel Altier, Align project director said: “The Align team has worked to significantly reduce the scale and visual impact of the structure. We are therefore excited to be revealing our designs for the Little Missenden vent shaft headhouse.
“Our designers have worked closely with stakeholders to design something that provides the operational functionality within the smallest possible footprint, reducing local construction and environmental impacts as far as practicable during the build.”