and Saint-Étienne have kept their lines of trolley buses and, Saint-Etienne is one of the few cities in France to have retained its trams (in use since 1881). Many cities also have their bus networks (Valencia the CTAV Chambéry the STAC, Villefranche-sur-Saône, Roanne, etc.). There are also networks of inter-departmental cars. In winter, additional lines open to connect the valleys to ski resorts. This is the case between Grenoble and Chamrousse. Finally, the airport Lyon Saint-Exupéry is accessible by regular shuttle bus from the major surrounding cities, including Lyon, Saint-Etienne, Grenoble and Chambéry. There are also links between Grenoble and Saint-Geoirs Grenoble and between Bouthéon Saint-Etienne and Saint-Etienne. The Rhône-Alpes region is undergoing profound changes with regard to its rail network and many projects are being developed to the [Express Network of the urban area of Lyons, The Project of the East Rail Lyon, the Tram-train from the west Lyonnais. Public transport links in Lyonnais Métro The Lyon Metro, in Lyon, opened in 1978 and now consists of four lines. It is part of the Transports en Commun Lyonnais (TCL) system of public transport. Like the SNCF, but unlike all other French metro systems (excluding the RER), Lyon metro trains run on the left, the result of an unrealised project to run the metro into the suburbs on existing railway lines. The loading gauge for lines A, B, and D is , more generous than the average for metros in Europe. The loading gauge for line C is . The Lyon Metro owes its inspiration to the Montreal Metro which was built a few years prior, and has the same rubber-wheel cars and station design. The total track length is , 80% of which is underground. The métro system consists of four lines, A-B-C-D, each identified on maps by different colours: Lines A and B Lines A (Perrache - Laurent Bonnevay) and B (Charpennes - Part-Dieu) were constructed using the cut-and-cover method, and went into service on May 2, 1978. Trains on both lines run on tyres rather than steel wheels. Line B was extended to Jean Macé on September 9, 1981, then to Gerland on September 4, 2000. A further extension to Oullins is expected to open in 2013. An extension to Vaulx-en-Velin La Soie on Line A opened in October 2007. Line C The Croix-Rousse-Croix-Paquet rack railway, which was refurbished in 1974, was integrated into the Metro in