The Turin–Modane railway line is long, fully electrified and double track. It has the standard Italian automatic block signalling system. The mountain section starts at Bussoleno and the two tracks take different routes. Much of the uphill line to Bardonecchia runs through tunnel between Bussoleno and Salbertrand, while the line running downhill from Bardonecchia, has a lower proportion in tunnel and takes a slightly lower route. West of Salbertrand the two tracks follow the same route. The uphill line was designed with "S"-shaped tunnels in order to reduce the gradient, increasing its length. Between Bussoleno and Salbertrand the two tracks are at the same level at the intermediate stations, except at Exilles, where the platforms are on different levels. This station is no longer in regular use, being separated by the valley from the village of Exilles and its fort. It can still be used if required for historical trains, or to pick up or drop off groups. On the western edge of Bardonecchia is the mouth of the tunnel, with a monumental gateway, enclosed by two round towers, all topped by battlements. In the nearby village of Rochemolles there are signs of the first entrance to the tunnel; it is now bricked up but it has some holes where the tracks inside can be seen.