Little Missenden Headhouse

The Little Missenden Headhouse is a single storey headhouse that will sit atop a 35-metre-deep ventilation shaft that will reach down to the Chiltern Tunnel below. It is set back from the main A413 in Little Missenden and is one of four structures that will be built to provide ventilation and emergency access to the 10 mile long (16km) Chiltern Tunnel.

Headhouse construction

Construction of the ventilation shaft is well underway, with the excavation complete and the site team moving on to the structural work inside the shaft.

The size of the shaft has been reduced to decrease the amount of material that has to be carried away by heavy goods vehicles (HGVs) during construction, reducing the amount of lorry journeys on local roads. We’re also building a signalised junction across the A413 to allow HGVs to safely access the construction site. This removes the need for them to travel to Great Missenden to use the Frith Hill roundabout.

Little Missenden Headhouse and Ventilation Shaft information boards

Headhouse design

The headhouse is designed to fit into the surrounding landscape, taking its inspiration from the style of local barns and other agricultural buildings.

The arrangement of the buildings is based on an agricultural courtyard layout, with the overall footprint of the compound kept to a minimum. Pitched roofs wrap around the buildings, creating simple agricultural barn forms. Buildings are orientated to reduce their perceived scale from key viewpoints. The zinc, painted steel and engineering brick will be durable and designed to age gracefully over time without losing robustness and quality. Dark, neutral colours will ensure the buildings visually recessive. The building colour and detail has been designed to blend into the landscape, using a simple palette of materials inspired by local agricultural and industrial buildings.

The landscape will be shaped to integrate with the profile of the valley edge, whilst woodland and shrub planting and chalk grasslands will reinforce the rural setting. We will retain as much of the existing vegetation along the A413 as possible, whilst planting substantial areas of native tree and shrub species to screen the buildings and structures and enhance biodiversity.