The Oslo Tramway (Norwegian: Oslotrikken) is a 131.4-kilometre (81.6 mi) tramway in Oslo, Norway which consists of six lines with 99 stops and has a daily ridership of 110,000. It is operated by Oslo Sporvognsdrift, a subsidiary of the municipal owned Kollektivtransportproduksjon who maintain the track and 72 tram vehicles on contracts with the public transport authority Ruter. The system operates on standard gauge and uses 750 overhead V DC. Depot, workshops and headquarters are at Grefsen (at the terminus of lines 13 and 17). There is also a depot at Holtet (along lines 18 and 19) that is home to the technical company InfraPartner, which maintains the track for the tram and metro systems in Oslo, and a small Office building for Oslo Sporveier.