Full Breakdown
Wildlife “Mammal Ledges” Added to New A421 Dual Carriageway
8/3/2026, 11:02:00 AM
Design Features for Small Mammals
National Highways has installed raised “mammal ledges” inside several small drainage tunnels beneath the new A421 dual carriageway. The dry pathways allow hedgehogs, rabbits, mice, voles and badgers to cross the culverts without entering water, preserving habitat connectivity along the route between the Black Cat roundabout in Bedfordshire and the Caxton Gibbet roundabout in Cambridgeshire.
Project Scope and Traffic Benefits
The 10-mile (16 km) dual carriageway will replace the only remaining single-carriageway stretch between the M1 near Milton Keynes and the ports of Harwich and Felixstowe. The upgrade aims to reduce congestion and speed journeys for the roughly 80,000 drivers who use the Black Cat roundabout each weekday. The road is scheduled to open in Spring 2027.
Official Statements & Responses
Paul Salmon, senior project manager with National Highways, said the scheme places “environmental protection” at the core of its design and construction.
Verbatim Quote
“Protecting the environment is central to both the design and construction of our scheme.” — Paul Salmon, senior project manager with National Highways
Why It Matters
By providing dry crossing routes for vulnerable small mammals, the ledges aim to mitigate the ecological impact of a major transport corridor while delivering faster, less congested travel for motorists. The approach reflects a broader trend of integrating wildlife considerations into large-scale infrastructure projects.
