Criteria of territorial characterisation


As part of consultation with local institutions, one of the most effective instruments for selecting the alternatives with the least impact consists of agreeing on the ERPA (Exclusion, Repulsion, Problematicity, and Attraction) location criteria.

The territory to be studied, with its land use classifications and related protections, is characterised on the basis of criteria that express greater or lesser appropriateness for hosting electricity infrastructures. In the national SEA, Terna and the Regional administrations agreed on a system of criteria based on four classes:

  • Exclusion: areas in which all construction is excluded.
  • Repulsion: areas which would preferably not be affected by projects, unless there are no alternatives or if there are only alternatives with less environmental compatibility.
  • Problematicity: areas in which passing is problematic for an objective reason, associated with specific aspects of the territory documented by the authorities involved, which therefore require further territorial analysis.
  • Attraction:areas to favour whenever possible after checking the area’s carrying capacity.


Each class of ERPA criteria includes several categories. Currently, the Exclusion criterion includes areas recognised by the law as areas of absolute exclusion, such as airports and military zones, and areas not directly excluded by law, which are however binding, through agreements on the subject made in advance between Terna and the authorities involved.

The Repulsion criterion includes areas that may be taken into consideration only in the absence of alternatives, protected natural areas, with regard to which specific agreements are made, and areas that are to be taken into consideration only if there are no more environmentally-compatible alternatives.

The Attraction criterion instead includes areas with good landscape compatibility and areas that already host line infrastructure, such as infrastructure and energy corridors, in which the location of a new line – if it is compatible with the area’s carrying capacity – is more sustainable than in new areas that do not have any line infrastructure.

The use of GIS (Geographic Information System) technology makes it possible to consider in an integrated manner all the information relating to the different types of land use mentioned and the binding protections (territorial, naturalistic, cultural, landscape, etc.), opportunely redistributed within the different ERPA criteria classes, so as to identify possible locations – in terms of “corridors” – that are sustainable for the NTG development projects, because they are in keeping and compatible with the organisation of the territory that they will be affecting.

The integrated planning process




The scheme illustrates the integrated planning process that Terna has implemented over the years. This process makes use of the prior consultation approach developed by Terna (“regional level”), harmonizing it with the procedure required by current legislation (“national level”).

“Integrated planning” is understood to mean that the work of planning the electricity system includes constant and reciprocal dialogue through consultation activities.

The national level is the formal level of application of the SEA procedure, as defined by current legislation (Italian Legislative Decree 152/2006 and later amendments and additions), which applies to the Development Plan and provides for the preparation of an Environmental Report (ER), in which the effects that the implementation of the plan or programme could have on the environment are identified, described, and assessed.

The national level is organised into the following different stages: orientation, formulation, consultation, approval, and monitoring. These are linked to the Plan, the Environmental Report associated with it and the Preliminary Report (PR) which characterizes the stage of orienting or screening.

The regional level constitutes the concrete level of the “dialogue with local institutions”, i.e. of the prior and voluntary consultation that Terna has carried out since 2002 with regional and local governments to seek and agree on the most viable and sustainable solutions for the location of the infrastructure necessary for NTG development.

An essential aspect of the integrated planning process described above is coordination between the two levels, leaving the appropriate decision-making autonomy at the regional level, which in any case proceeds according to the criteria and methods established at the national level.

The SEA Portal 

To improve quality and transparency with its stakeholders, in 2011 Terna created a new interactive corporate portal, specifically devoted to the SEA procedure of the NTG Development Plan.

Through the SEA Portal ( users can consult not only the Environmental Report, with reference to the maps, but also the data on SEA monitoring of implementation of the Plan.

The map portal also makes it possible to follow the organisation of the Plan on a regional basis, in the environmental, social, technical and economic dimension only, or as a whole, using the assessment indicators and the aggregate sustainability indexes.

Finally, within the SEA Portal, it is possible to use the web to monitor the gradual implementation of the Plan, using maps, on the basis of specific indicators defined to assess any changes that may occur between the plan agreed (“ex ante”), the project authorized (“in itinere”) and the work done (“ex post”).