 In 1985 the water bus service is made part of the Oslo Sporveier network, though it remained operated by the private company Oslo Fergene.In 1991 the companies Ekebergbanen and Holmenkolbanen were merged into Oslo Sporveier, and until 2004 a few private owners had a very small ownership in Oslo Sporveier.Also in 1991 the first public service obligation was issued on the bus service.