Natural England reports that bridges built across roads and railways to allow wildlife movement can stop species from becoming isolated and reduce the number of traffic accidents.
The bridges are known as green bridges, landscape bridges or wildlife overpasses and are usually planted with a variety of local trees or shrubs and other vegetation. They allow birds, mammals and insects to keep moving despite a road or railway blocking their path.
Green bridges are common in Europe and North America, but only a few have been built in Britain.
The report: “Green Bridges – a literature review” was undertaken by Land Use Consultants on behalf of Natural England. It looks at scientific evidence from 56 examples across the world, ranging from the Mile End green bridge in east London to the Compton Road faunal overpass in Brisbane, Australia.
It is the first worldwide study of green bridges and has found that they could become an important part of the sustainability of future transport projects by:
- creating a safe crossing point for wildlife movement
- joining up habitats and connecting colonies, as they are also used by wildlife as a home in their own right
- creating a crossing point for people and benefit pollinators
- integrating roads and railways into the surrounding landscape
The UK currently has a small number of green bridges. One of the most celebrated spans the A21 at Scotney Castle in Kent in the High Weald Area of Natural Beauty (AONB).
Completed in 2005 as part of a dual carriageway by-pass for Lamberhurst, it enabled the historic drive to the castle to be preserved, reduced the impact on local landscape and was soon being used by dormice.
In London, a green bridge was built to overcome the fragmentation of Mile End Park by a number of roads and railway lines. Spanning five lanes of the A11, the Mile End green bridge is 25m wide with landscaped parkland.
Rainwater runs off the bridge into tanks on either side and is then recycled to maintain the water content of the soil.
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