A case study on using special star towers for multiple overhead power line crossings

In present days acquiring a corridor for construction of a new transmission line without crossing of existing power lines is almost not possible. As the number of transmission lines increasing every year by year, it is inevitable that a new line cannot be constructed without any existing power line crossings. In general there are two ways of crossing any power line i.e., under crossing or overhead crossing. If the conductor level of existing power line is in a sufficient height from ground level and if it is possible to maintain required phase clearances by taking the proposed line underneath the existing line, under crossing can be done. If it is not possible to make under crossing, the other option is to make overhead crossing of the existing lines. This requires high extension towers depending upon the height of the top conductor/Earthwire (OPGW) of existing power line and the required vertical clearances to be maintained for the particular kV lines. Due to this, the tower weight and foundation volumes increase significantly. If the power lines have to be crossed in the residential areas, providing such huge extension towers is very difficult in many aspects such as acquiring land for such huge foundations, aeronautical clearance etc., we have encountered similar kind of situations for power line crossings where we cannot cross by under crossing. Thus, to make the crossings in a simple and economical way, we have adopted a new kind of tower configuration which is called as STAR tower. In this case study, we are presenting the difficulties faced in the power line crossing while executing 380 kV D/C OHL in Saudi Arabia and the methodology adopted for overcoming the difficulties in multiple overhead crossing by using these STAR towers.