Wildlife & Traffic
A European Handbook for Identifying Conflicts and Designing Solutions
Summary
This chapter describes the principles and key issues for the successful integration of highways, railways and waterways into adjacent landscapes and habitats. The emphasis is on those aspects of integration that are relevant to the minimisation of habitat fragmentation.
6.1 Introduction
6.1.1 Potential effects of infrastructure development on landform
The construction of new infrastructure can impact on landform in a number of ways:
- Habitat loss and fragmentation of nature.
- Changes to the water table and drainage patterns and systems.
- Physical barrier and visual intrusion due to:
i) the infrastructure itself;
ii) large earthworks;
iii) embankments crossing valleys and low-lying land;
iv) cuttings which fragment habitats and create scars on hillsides; and
v) unsympathetic junctions that can form barriers to wildlife movement and intrude into the landscape. - Good alignment and sensitive design can be employed to minimise the magnitude of these effects.
6.1.2 Multi-disciplinary approach
The integration and minimisation of fragmentation effects of linear transport infrastructure is best achieved by employing a multi-disciplinary project team of engineering and environmental professionals. Decisions on design will require environmental constraints to be balanced against costs, but ultimately will be dependent upon engineering feasibility and safety considerations. However, consideration should be given to changing engineering standards to accommodate environmental constraints.
- The main design objective is to create a harmonious linear transport infrastructure that integrates with the natural environment.
- The infrastructure should have adequate connectivity above and below the highway, railway or waterway to maintain links and corridors for fauna and flora.
All the engineering elements of the infrastructure should be designed for minimum intrusion into natural habitats, e.g. use of a viaduct to cross a valley rather than a solid embankment.
6.1.3 Mitigation principles
The best mitigation involves the selection of the least damaging route alignment combined with sensitive scheme design. The underlying principles are avoidance of damage or direct effects or, if this cannot be achieved, mitigation of impacts. Where impacts cannot be fully mitigated compensation may be necessary. Particular attention needs to be given to the detailed design of earthworks - these are integral to successful mitigation of the scheme and can be blended with the adjacent landscape. Earthworks are considered in more detail in the following section. Other important mitigation considerations:
- Full use should be made of legal powers for the acquisition of land and/or procedures concerning the use of land under licence to install mitigation measures.
- Where a new or improved road or railway affects a site of European importance (i.e. designated under the EU Birds or Habitats Directives), land to support a compensatory habitat will need to be secured, developed and managed appropriately.
- Design for effective and long-term maintenance and recognise the limitations of prevailing site conditions.
All the engineering elements of the infrastructure should be designed for minimum intrusion into natural habitats, e.g. use of a viaduct to cross a valley rather than a solid embankment.