Improving biodiversity and resilience on the UK rail network

Restoring a wetland area is boosting biodiversity while also improving climate resilience on the UK rail network, in a first of its kind project in the east of England.

The seven-hectare site, located in Cattawade, Suffolk, was drained almost 180 years ago to protect the railway embankment of the London to Norwich line, removing a wetland habitat and the ecosystem in the process.

Ramboll worked with contractors, QTS Group, to undertake the restoration on behalf of Network Rail. Working in collaboration with the Network Rail Project Team, nature-based solutions were deployed including the building of a ‘rock armour’ wall on the railway embankment, water channels to enable flow across the area, and a series of mounds above the water line to encourage wetland birds to nest and lay eggs.

As the designer, Ramboll’s services were used through the project lifecycle from the initial options assessment, securing environmental and stakeholder support, and the development of a buildable design for implementation.

Combining advanced engineering with nature-based solutions

Ramboll’s front-end engineering services determined the scour problem and site constraints, to propose remediation options based on the survey, LiDAR, and ground information. This identified the rock armour and slope regrade solution as the most suitable option for the site.

Ramboll then progressed the preferred option into design development and formal rail assurance documentation. This included preparing the permanent works design, drawings, design criteria, construction and temporary works assumptions, design and check certification, and designer’s risk information to support approval and delivery.

The Wildlife Trust Consultancies prepared ecological work covering a desk study, an extended UK habitat survey followed by recommendations for biodiversity enhancements and ecological supervision to support the scheme and its approvals.

Speaking about the project, Anthony Guay, Head of Department - Water, said:

“Ensuring the resilience of the UK rail network is essential in keeping the country moving, as this line connects Norwich to the capital. By using nature-based solutions and working with the unique attributes of the site, we can find solutions that mitigate against the effects of climate change while also increasing the biodiversity net gain.”

Restoring biodiversity and strengthening network resilience

Wading birds are already returning to Cattawade, such as curlews, avocets and oystercatchers. The planting of sea aster serves to attract the return of the sea aster mining bee - a rare species rarely found outside of Anglia and the southeast coast.

The wetland aims to slow the flow of the water impacting the embankment, making the “rock armour” even more effective and enhancing the site’s the long-term resilience against climate impacts.

The improvement works at Cattawade represents an important step in making the railway more sustainable for future generations, while restoring natural habitats and reducing the impact of extreme weather.