Remodelling of a wetland area

As part of a project to widen the Valangin-Dombresson cantonal road, the Roads Inspectorate of the canton of Neuchâtel planned a series of measures designed to mitigate damage to the landscape and local ecology.

Problem
The cantonal road between Les Ancédants and Bayerel passes through an intensively farmed landscape. The River Seyon - a near-natural watercourse, whose riparian vegetation has been preserved - flows through the area. Damp forests alternate with bushes, individual trees and damp meadows. The road is lined with maple trees.

The watercourse and the riparian vegetation attract a wide variety of wildlife, especially birds, mammals and amphibians.
In view of the volume of traffic, the risk of accidents on this narrow, tree-lined road had become unacceptably high. In addition, the local road maintenance team noticed unusually large numbers of animals killed on the road. It was considered essential that the situation should be remedied.

The project involved widening of the carriageway, which would have affected the natural habitats and the trees along the roadside. This aroused the opposition of conservationist associations, which called for an environmental impact study, together with proposals for the redesign of this section.

Protection measures
Following the environmental impact study, an option was selected which preserves the attractive sites and ensures the best possible design of the roadside areas.
.

		Map of layout of wetland area
		Remodelled damp zone
		Newly planted trees
		Protective structure for small animals

The following measures were implemented:

• To increase road safety and facilitate road maintenance, the part of the maple avenue that had been destroyed was replaced by trees planted at some distance from the road (restoration in accordance with Art. 18, para. 1ter of the Federal Law on the Protection of Nature and Cultural Heritage).
• To supplement the existing vegetation, the grass roadside verges were planted with low hedges and shrubs.
• A damp hollow - classified as a protected area - which had dried up and become overgrown with scrub was restored by excavating a water channel.
• Between the damp zone and the watercourse, protective structures for amphibians were installed along the road.
• Crossings in the form of tunnels beneath the road were provided for small animals.

The replacement of the part of the maple avenue that had been destroyed was an integral part of the road reconstruction project and was therefore not financed by fuel tax revenues. However, the other measures can be subsidized in part from these funds, as they would have improved the situation even in the absence of the construction project.