Whether transmission lines are to be constructed overhead or placed underground has to be decided on a case-by-case basis and in accordance with objective criteria. For this purpose the Swiss Federal Office of Energy (SFOE) has developed a "transmission lines" evaluation model. The main objective of the new model is to evaluate various options in order to define the most suitable corridor for transmission lines. At the same time, the question whether transmission lines should be placed overhead or underground can be answered and the licensing procedure can therefore be accelerated. The model comprises four pillars, each of which contains three or four groups of criteria (spatial development, technology, environment and the economy). Projects are examined and evaluated on the basis of the criteria. After initial findings have been obtained, minor adjustments will be made to the new model and a manual will then be prepared.
To determine whether a high-voltage transmission line project is to be carried out as an overhead line or an underground cable for voltage levels 3 to 7, the additional cost factor has to be calculated according to the provisions of the Federal Transmission Lines Ordinance. To determine this factor, the Swiss Federal Office of Energy has prepared a set of guidelines and an Excel file that must be used for each project concerned.