The Oslo Metro is a rapid transit system serving Oslo and Bærum in Norway. The system is municipally-owned by Sporveien, and operated by its subsidiary Sporveien T-banen under contract to Ruter, the Oslo public transport authority. The metro has a daily ridership of 200,000, and serves 101 stations. The system consists of eight lines that operate as branches from the Common Tunnel—the shared section that runs 4.8 kilometers (3.0 mi) through the city center. In addition, the Ring Line operates in a loop north of the city center. There are six train services, numbered 1 through 6, that each operate from one branch via the city center to another branch or to the Ring Line. All services run every 15 minutes. Each branch has one service that operates to its terminus, except for the Lambertseter