Any new road has the potential to put wildlife and habitats at risk, both during construction and when in use, and the Northern Distributor Road is planned to run through an important area for nature conservation between the Broads and the River Wensum. This is reflected in its design and landscaping, which have been influenced by extensive surveys over several seasons.
This work identified particularly valued and vulnerable sites, and recorded the extent of wildlife populations. It established the presence of badgers and other mammals, widespread breeding bird populations including barn owls, and a single breeding pond for great crested newts. The surveys confirmed the area as particularly important for several species of bat.
Habitat loss from the road includes about 5.3 ha of semi-natural woodland, 4.4km of species-rich hedgerow and 9.7km of lower quality hedges. One county wildlife site (Ortlan’s Grove) will be directly affected, although the scheme design has ensured the impact will be minimal.
Ways of reducing the impact on sensitive locations have been built into the landscaping scheme, including innovative wildlife measures that set new standards for road schemes in areas of high nature conservation value.
For every tree felled, more than five trees, of various sizes, will be planted. Along with shrubs and new hedges, the total area will add up to 61.2 ha of broadleaved woodland. The planting and landscaping is designed to add to and link existing habitats, preserving and improving ecological corridors, including woodland, scrub and grassland, hedgerows and wetland.
Wetland, watercourses and groundwater can be vulnerable to polluted road run-off containing road salt and other contaminants, so sustainable drainage systems will use lagoons and reed beds and other measures to improve water quality before it enters streams or is allowed to soak away.
The area is of national importance for bats, with ten species identified, including colonies of rare Barbastelles. A number of bat roosts in trees and buildings will be lost, and bat houses are proposed to provide replacement roosts in two locations, along with bat boxes within woodlands close to the route.
The new road will also cut across established bat foraging flight paths, and a new design of wire bat gantries is proposed to help keep bats clear of traffic, along with green bridges on Marriot’s Way and Middle Road (carrying hedgerows over the NDR), an underpass, and bat friendly features on other bridges.
Badger populations are known in the area, and badger fencing will be used where there is a particular risk of them getting on to the road. Breeding birds are found along the whole route, including barn owls.
A breeding pond and surrounding habitat for great crested newts will be lost during construction, but other nearby ponds and habitat will be protected, and four new ponds are being created. Amphibian fencing will be used to stop newts straying on to construction areas, and as many as possible will be trapped and moved to suitable safe areas.