A new wildlife bridge is soon set to open over one of the UK's busiest roads, marking a major milestone in the £330 million upgrade of the A30 between the now-defunct Chiverton roundabout and Carland Cross. National Highways is applying the finishing touches to its A30 dualling project in Cornwall. The dual-deck green bridge at Marazanvose has been built by contractors Costain as part of the wider A30 upgrade led by National Highways. Spanning 49.3 metres in length and 12.5 metres in width, the structure stretches across four lanes of the new dual carriageway and two lanes of the former A30, now redesignated as the B3288.

Following topsoiling work last summer, the bridge has recently been planted with native trees and hedgerows, giving it the appearance of a natural strip of countryside floating above the traffic below. Two traditional hedgerows have been created using species such as hazel, hawthorn, holly, dog rose, elder and wych elm.

Additional hazel and hawthorn trees have been planted, along with grasses and wildflowers, with further seeding and planting due to take place in the spring.

Once fully completed, the bridge will provide a safe crossing point for a range of wildlife, including badgers, voles and other small mammals, as well as insects and birds. It will also serve local landowners by maintaining farm access and incorporating a bridleway for horse riders.

Green bridges remain rare across the UK and this is only the third such structure delivered by National Highways on the Strategic Road Network.

It is also the second in Cornwall, following the A391 Carluddon road bridge. Similar projects have previously been completed over the A556 near Chester and the A21 at Scotney Castle in Sussex, with further green bridges under construction near Gloucester on the A417 and at Cockrow in Surrey as part of the M25 Wisley interchange scheme.

The Marazanvose bridge forms a centrepiece of the environmental legacy of the A30 Chiverton to Carland Cross upgrade, which opened to traffic in June 2024. Around 960 tonnes of soil, sustainably sourced from the scheme's own earthworks, have been laid across the bridge deck and embankments. Across the wider project, some 87,000 trees are being planted to help integrate the new road into the landscape

Andrew Alcorn, National Highways' Programme Manager for the A30 Chiverton to Carland Cross scheme, said: "We're really proud of the environmental work we've invested in this project, and the creation of the green bridge is a leading part of that.

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"Along with other environmental measures, we've built a total of 33 multi-species crossing points as part of the project, and we look forward to seeing the bridge bloom for many years to come, providing a real legacy for the scheme and for Cornwall."

Tom Kenyon, project director at Costain, said: "We're creating a more sustainable future by implementing nature-positive initiatives that enhance biodiversity. This includes designing and constructing green bridges which provide safe crossing points to join up habitats and make wildlife populations more resilient.

"The Marazanvose Bridge is one of many environmental benefits of the A30 dualling scheme, and in addition to deploying a circular economy approach for the topsoiling of the bridge, we've been able to forecast a biodiversity net gain of more than 20% across the scheme."

With the main carriageway open since summer 2024, finishing works are now nearing completion. Local road connections at Trevalso and Pennycomequick have opened, the former A30 between Chybucca and Chiverton has reopened, and lighting and CCTV installation works have been finalised along the route. Landscaping will continue into the spring, followed by a five-year maintenance period to ensure successful establishment of planting across the scheme.