Habitat fragmentation should be minimised when planning new infrastructure or the upgrade of existing infrastructure. Carrying out Strategic Environmental Assessments (SEA) on plans and programmes and Environmental Impact Assessments (EIA) on projects ensures that environmental considerations are taken into account at an early stage. SEA and EIA should be carried out according to EU directives and their national implementations (Sections 5.2 and 5.3).

The overall aim of the SEA and the EIA is to identify possible environmental impacts of plans and projects before a decision about implementation is made. Another aim is to ensure public consultation on the project. Before a plan or project is adopted and before any construction begins, all SEA and EIA are subject to a public hearing. At this stage, relevant authorities, stakeholders, NGOs and the general public can comment on the plans and influence the project before a final decision on implementation is made (Figure 5.1).

As some degree of fragmentation is inevitable when building a road or railway, mitigation measures must be taken into consideration to ensure permeability of the infrastructure in dispersal corridors and priority habitat areas. In situations where infrastructure crosses especially vulnerable areas or where mitigation measures are inadequate or impossible, compensatory measures may be necessary (Chapter 8).

Fragmentation issues relating to existing infrastructure are somewhat different. For a large part of the existing infrastructure, mitigation measures may not have been taken into consideration during planning and design.

In these situations, the fragmentation brought about by the existing infrastructure may have already affected the area, and other sources of fragmentation, unforeseen at the time of the study, may have appeared. New evaluation may be necessary if the assessments that were originally made are outdated (Section 5.5).