Power transmission line traverse in various geographical areas and the ground level is not uniform everywhere. So body extension and leg extensions will provide great strength to the transmission tower to hold the load which applies to power transmission tower.
Body extension is use for increase the tower height and this will also obtain the required minimum ground clearance. These types of body extensions are widely used for road crossings, river crossing and where ground obstacles are happens. Transmission tower heights are normally different in one transmission tower to another tower. The major height different is apply by body extension and leg extensions. Normally body extensions are applied in +3 meters,+6 meters, +9 meters, +12 meters … and +25 meters in height.There are very few tower which exceed the body or leg extension more than +25 meters.Place where body extensions is higher than 25 m the suitability is checked by reduce the span length and and angle of deviation. For the transmission lines traverse in hilly terrain negative body extensions can applied to tensions towers by consider the economic factors.