Costain is making final preparations for the completion of a new green bridge in Cornwall that is set to deliver environmental benefits and enhance recreational access in the area.

The Marazanvose Bridge, part of Costain's delivery of the A30 Chiverton to Carland Cross dualling scheme for National Highways, spans 49.3 metres and measures 12.5 metres wide. Designed to connect habitats and improve biodiversity, the structure will allow safe passage for wildlife, pedestrians, and horse riders across both the new dual carriageway and the de-trunked B3288 — a section of the old A30.

Costain has now begun topsoiling the bridge using approximately 960 tonnes of earth recovered from the scheme’s own works, demonstrating a circular economy approach. This preparation will enable the bridge to support a variety of local species, including badgers, voles, insects, and birds. Planting will take place later this year.


Green bridges are increasingly recognised for their role in improving road safety and sustainability by providing safe corridors for wildlife. Costain previously constructed the first such bridge opened by National Highways, as part of the A556 upgrade in Cheshire.

Tara McCracken, Safety, Health and Environment Manager at Costain, said: "As part of a collaborative effort across the scheme, we've placed a big emphasis on ensuring we’re providing a positive legacy and delivering ecological and environmental benefits above and beyond what’s required. We’re forecasting a biodiversity net gain of more than 20% across the scheme.

"The Marazanvose Bridge exemplifies this commitment and we’re very happy to now be making the final preparations on the structure to enable local wildlife to flourish and ultimately support a sustainable, decarbonised future for Cornwall and the surrounding areas."

The green bridge is one of several environmental features included in the nine-mile road upgrade, which aims to improve connectivity for both people and nature. In total, 33 multi-species crossing points have been created, along with a dedicated bat barn, eight miles of traditional Cornish hedging, restored hedgerows, and the relocation of local reptile populations. Over 28 miles of new drainage have also been installed as part of the wider ecological strategy.