Latest designs revealed for Little Missenden’s HS2 vent shaft headhouse

HS2 Ltd has revealed the final design for the Little Missenden vent shaft headhouse, which will provide ventilation and emergency access to the high-speed railway’s 10 mile-long Chilterns tunnel below.

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The headhouse is one of four that will be built above a vent shafts leading down to the high speed rail tunnel below and is similar in style to the HS2 headhouse at Chalfont St Peter announced earlier this year.

Set back from the main A413, the single story 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 Little Missenden headhouse will sit atop a 17.4m diameter, 30m 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 Ltd’s main works contractor Align JV – a team made up of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.

HS2 Ltd’s senior project manager, Mark Clapp said:“Designs for the Little Missenden headhouse are the culmination of many hours’ work to develop a scheme that both serves the needs of operating HS2 and is in keeping with local design heritage. Our four-week engagement with the community is an opportunity for them to tell us their views of the scheme. As part of this programme we’ve arranged three online webinars where people will hear about how the designs were developed.”

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.”

Ian Thomas, engineering manager for designers Align D, said: “Set back from the A413 dual-carriage way, the single-story buildings will be wrapped in a landscaping solution that minimises their visual impact. Taking its inspiration from the style of local barns and other agricultural buildings, the headhouse is designed to fit into the surrounding landscape. The pre-weathered grey zinc roof will age naturally over time, without loss of robustness or quality.These proposals are the result of integrated work across the design team, alongside collaborative engagement with the Chilterns AONB Review Group.”

Today’s news accompanies a four-week public engagement programme, which is seeking people’s views on aspects of the scheme including the design of the headhouse as well as plans for landscape and the area’s ecology. Click here to access information about the designs and online survey.

During the engagement period HS2 Ltd will be holding three online webinars on 4, 9 and 12 November. For more information please click here.

The engagement period ends 25 November.