‘Six lanes of tarmac and vehicles doing 70mph’: can ‘green bridges’ help animals cross the UK’s motorways in safety?

The Cockrow bridge connects two lowland heath nature reserves split by the A3, giving wildlife such as adders and other reptiles, as well as more common animals such as roe deer and foxes, a chance to cross and allowing biodiversity to recover. Photograph: Rob J Follett/Shutterstock

When James Herd moved near to Wisley Common 17 years ago, the heathland nature reserve was teeming with wildlife. “I’d take the dog around the common in spring and summer, and every few hundred metres I’d hear the rustle of a lizard in the undergrowth – and I’d see adders,” he says.

But over the past decade, the Surrey Wildlife Trust’s director of reserves management, who oversees the internationally important habitat, has seen that wildlife become depleted.