Sheephouse Wood bat protection structure

The Sheephouse Wood bat protection structure is being built alongside Sheephouse Wood in Buckinghamshire.  The structure itself is a significant piece of engineering which is required to have a design life of 120 years. It is around 1km long, up to 10m high and will be four tracks wide. It also includes extensive safety requirements to separate the two operating railways and a green bridge built into the north portal. 

The 56 hectare woodland is home to several different bat species, including the most northerly known colony of the rare Bechstein’s bat. All bats are legally protected in the UK and the structure will allow bats to cross the line without being harmed by passing trains. 

This initiative is part of a broader environmental commitment in the area, featuring new green bridges and extensive tree planting to support wildlife and boost biodiversity. 

Construction progress

Construction began in 2023 with the initial focus on the base slab and side walls that will support the arched superstructure.

Assembly of the arches that will form the superstructure has now begun, starting from the north portal. In this area, the arches are being installed back-to-back to form a green bridge, with landscaping and vegetation planted on top to allow wildlife to cross the railway. 

For the rest of the structure, the arches will alternate with steel mesh panels to allow natural ventilation. Each of the arches are made of two curved segments which weigh between 12 and 27 tonnes. Two cranes are required to lift each of the segments into position and support them while the joint is sealed with concrete. 

Structural design

The design is based around a series of arches each around 23m wide and 10m high. Although not technically classed as a tunnel, this structure has been carefully chosen as being the most effective solution to match our design considerations. The design is durable and requires little maintenance, reducing overall costs and materials. 

Once complete, the structure will be absorbed into the local landscape and embed itself into the backdrop of the woodland. It will provide adequate shielding for bat flight paths from passing trains and provides connectivity points for wildlife with a green bridge and underpass. 

The structure is built with future growth in mind, providing space for two additional tracks that could be used for freight or for a future local rail service between Aylesbury and Milton Keynes.