From March 1991, Oslo Sporveier took into use four propane-fueled buses from Arna. One 5 July, the first routes in Oslo were taken over by public service obligation contracts.
From March 1991, Oslo Sporveier began utilizing four propane-fueled buses from Arna as part of its services. A significant milestone occurred on July 5, when the city's public transportation system was taken over by public service obligation contracts for the first time.