A comprehensive bus and tram network covers the region. , the Brussels tram system consists of 17 tram lines (three of which – lines T3, T4 and T7 – qualify as "premetro" lines). The total route length is , making it one of the largest tram networks in Europe. The Brussels bus network is complementary to the rail network. It consists of 50 bus routes and 11 night routes, spanning . Since April 2007, STIB/MIVB has been operating a night bus network called Noctis. On Fridays and Saturdays, 11 bus routes operate from midnight until 3 a.m. They run from the centre of Brussels to the outer reaches of the Brussels-Capital Region.