The impact study is usually the subject of a public hearing -- a very general procedure, whose content varies from one country to another.
Important variables discussed during public hearings include the duration, the procedures used and, particularly, the capability of opponents to stop progress. This is an extremely worthwhile procedure which can help to avoid overly technocratic decisions.
Unfortunately, however, public hearings more often result in the expression of individual interests than in the disclosure of
the public interest, owing to the absence of any evaluation of consequences in financial terms, and because the quantitative estimates of environmental damages are usually imprecise. In order to help overcome this disadvantage, the quantification and monetary evaluation of environmental effects must be further developed.
The question arises as to how the different types of social costs are assessed in these environmental impact studies.