The technical specialists in grid development and in grid construction and maintenance guarantee an efficient and safe grid infrastructure. They are also responsible for carrying out the necessary modernisation work on the extra-high-voltage grid. Their role includes planning, construction, management and maintenance of the grid installations. They also control all the services associated with overhead and underground lines, as well as switching and control technology. In practice, that means that they ensure that over 12,000 electricity pylons, 6,700 kilometres of power lines and 41 connections to the European electricity grid function perfectly, both indoors and out.