The VIA (environmental impact evaluation) is a decisional instrument used by experts and authorized people in order to evaluate projects for the enlargement or the construction of industrial areas, communication structures and others (all included in the regional laws or in the VIA). Studies of environmental impact evaluation  include all the possible direct or indirect effects of a plan, and all the possible alternatives: on human beings, fauna, flora, ground, superficial water and groundwater, air, climate, landscape and heritage (social, material, cultural and environmental).

As a first step in a VIA project, the subject that proposes the project is obliged to draw up an environmental impact study, together with the institutions that will then evaluate the final work. This kind of study should include: data, analysis and information such as the project's description and the existent alternatives, the explanations of choosing that plan under the point of view of the environmental impact, a comparison among the projects, a description of the environmental characteristics that would get changed after the application of the project and of the calculated effects of it and a description of the measures that would be undertaken in order to avoid, reduce or counterbalance negative effects of the project on the environment. This plan would be then evaluated by the experts during the VIA process. The evaluation of incidence is the preventive process every project has to undertake, due to its possible reflections on a site of "Natura 2000 Network" (Reg. 79/409/CEE and 92/43/CEE)), alone or together with other plans and projects, taking into consideration the main aims of conservation of the site.

This is done by examining the interferences among plans and projects not directly connected to the conservation of habitats and species for which they had been chosen, and therefore able to condition the environmental equilibrium. Moreover, the evaluation of incidence is an instrument of prevention that analyses the effects of the interventions in a dynamic ecologic system, considering all the relations among sites and their contribution to the total coherence and functionality or Natura 2000 Network, both on a national and European community level.

That's why the evaluation of incidence is a safeguard instrument, particular for every site, setting it in the activity of the entire network.

Some Examples:

Alonte (Vicenza): evaluation of incidence for a limestone quarry and intervention of landscape and environmental rehabilitation on hills.SIC of Western Berici Hills.

Sossano (Vicenza): evaluation of incidence of the general town plan