Supporting Technical Paper 4.
of biological and landscape diversity in the development of road transport
by Mr. Jean-Marc Fauconnier, Conseil en Environment, France
directly or indirectly, roads and motorways have an adverse influence on
diversity, both by the fact of their existence and as a consequence of their use
by traffic and their maintenance, causing negative (and occasionally positive)
effects on land areas (biotopes and landscapes) and ecosystems (biocenoses and
plant and animal species).
of road transport on biological and landscape diversity
The impact on land areas
This impact directly concerns the areas crossed in terms of landscape (human environment) and biotopes (supporting biocenoses) and falls into the following main categories:
The impact of construction sites
Construction work may disturb habitats, affect the species which they harbour and adversely influence biodiversity in areas varying in distance from the construction zone. The causes are, in particular, site clearing and earthworks, activity and noise, uncontrolled liquid wastes, as well as borrow pits and storage areas for materials.
The impact of toxic emissions
Directly related to traffic, these emissions have an adverse effect on air, water and soil quality, and consequently on biotopes and ecosystems, mainly in the areas along both sides of the road (local influence over 50 to 100 metres), but they may also affect more distant areas (depending on methods of transfer, in particular through the air).
The direct impact on fauna
For the habitats which it crosses, which are occupied by animal species of varying mobility, the road represents a hostile zone (fragmentation effect) that animals may try to cross in response to their biological needs (access to traditional feeding or breeding grounds, or migration routes). This being so, the risk of animal mortality due to collisions will depend on infrastructure characteristics, traffic density and habitat type.
The indirect impact
effects (away from the actual road area) which may be created by spatial changes
and the redistribution of human activities in the area concerned (industrial
estates at intersections and agricultural consolidation) often account for a not
inconsiderable part of the impact on biological and landscape diversity.
policies and practices
The need for a common approach in the various policies pursued
Better implementation of the principle of continuous assessment
Although the principle of continuous environmental assessment is generally accepted, in practice environmental experts work consecutively on separate studies without any real continuity. This leads to a damaging loss of information between the various project stages. A sole co-ordinator responsible for interdisciplinary dialogue and the temporal continuity of environmental assessments would prove more effective.
Development of operational methodologies and tools
Ecology and landscape experts often lack reference material and tools for analysing, assessing and planning. This dearth contrasts with proven practices in road engineering and means that ecological and landscape factors are given inadequate consideration in the choices made and measures taken.
Guidelines for biodiversity-oriented professional practices
When deciding whether a new road is justified, account
must be taken of alternative modes of transport and serious consideration given
to the zero option.
Environmental impact studies must offer choices in
terms of spatial planning.
The study area must be large enough to include all
effects and allow a functional approach to landscapes and ecosystems.
Crucial issues, key species and sensitive areas must
be defined according to scientific criteria alone, disregarding pressure groups.
When choosing a new route, account must be taken of
biological and landscape diversity, and the areas of least impact first
The importance of ecological and landscape criteria
must be sufficient to balance that of economic and technical requirements.