The assessment of long-term potential environmental impacts upon adjacent habitats resulting from motorway development is an essential element in the planning and decision-making process. It is also an important tool in helping to reduce conflict between developers and conservationists. With increasing pressure on high quality woodlands brought about by new transport infrastructure, as full as possible an understanding of the likely effects is essential if these sites are not to be damaged irreparably. Small woodlands appear more susceptible to physical impacts, whereas qualitative changes assume more importance for larger woodlands. A systems approach enables the major impacts to be identified, and in so doing broadens the scope and efficacy of environmental impact assessment.