17 - Has putting the line under ground been considered?

During the consultations, The Highland Council, Cairngorms National Park Authority and Scottish Natural Heritage commissioned a study into the technical, financial and environmental issues pertaining to the undergrounding of Extra High Voltage (EHV) transmission lines. Amongst other things the study found that EHV underground cables (UGC):

• do "not offer the same level of availability as an overhead line……prolonged faults are more frequent in underground cables than overhead lines and they also take, on average, much longer to repair";
  
• involve 'motorway-width disturbance' and the movement of considerable volumes of spoil;
  
• need 'sealing end compounds which are required where the cabled sections of the route connect to overhead line sections'; and
  
• cost between six and twelve times more than overhead lines 'based on assumptions generally favourable to UGC'.

At the Public Inquiry the Reporter heard evidence about the consideration given to undergrounding as an alternative. Reports were prepared which considered sections of undergrounding proposed by third parties. The conclusion reached in the reports was that an overhead line remained the best option, having regard to the companies fulfilling their statutory obligations.