Oslo has Norway's most extensive public transport system, managed by Ruter. This includes the six-line Oslo Metro, the world's most extensive metro per resident; the six-line Oslo Tramway; and the eight-line Oslo Commuter Rail. The tramway operates within the areas close to the city centre, while the metro, which runs underground through the city centre, operates to suburbs further away; this includes two lines that operate to Bærum, and the Ring Line which loops to areas north of the centre. Oslo is also covered by a bus network consisting of 32 city lines, as well as regional buses to the neighboring county of Akershus.