The trains remained unique, using a grey and blue colour scheme for the 2nd class cars and red and yellow for 1st class until 1972. When Line 7 was modernised with new MF 67 stock between 1971 and 1973, its old Sprague-Thomson trains were transferred to Line 12 to replenish the worn out equipment from the Nord-Sud company. The last train was replaced in May 1972. Line 12 continued to use the Sprague-Thomson equipment for another six years, until 1978, when it was provided with new MF 67 stock. Intermittently, the MF 2000 stock trains are tested along the Line 12 corridor. Workshops The rolling stock of Line 12 is maintained at the Vaugirard workshop, situated underground in the 15th arrondissement of Paris between the rues Croix-Nivert, Desnouettes and Lecourbe, and Lycée Louis-Armand. They connect with the main line on the tunnels toward the Mairie d'Issy station, north until the Porte de Versailles station. It is also connected to the Petite Ceinture, a minor disused railway, by tracks which cross Rue Desnouettes. As with all rolling stock on the system, heavy maintenance, such as the replacement of worn parts (batteries, paint, springs, etc.), happens at the Choisy workshops. Opened in 1931, the Choisy workshops are underground in the 13th arrondissement, close to the Boulevard Périphérique, and accessible via a fork in line 7. There are two parts, one for maintenance of carriages of Line 7, the other for repairs on trains from all lines on the network. The workshops cover an area of approximately . In 2007, it was staffed by 330 workmen. Ticketing and finance The Metro ticketing system uses the "t+" ticket, which permits a journey of any distance and allows unlimited transfers between Metro lines and to the RER within central Paris. The cost of operating the line is met by the RATP, though ticket prices are set politically and do not reflect the true cost of operating the system. The difference is covered by the Syndicat des transports d'Île-de-France, the regional public transport coordinating authority. It sets the general conditions, frequency and duration of services. Their operating cost is financed by an annual block grant raised through a transport tax on businesses and payments from local authorities. Traffic Line 12's traffic load is about average for the Métro; the total number of travellers is less than half that of Line 1 and approximately two-thirds of lines