Akersbanerne continued construction on the section from Bryn to Oppsal. The original reason for terminating at Bryn had been the prolonged construction of Bryn Bridge across the Trunk Line. The extension to Oppsal was completed in January 1926. By then KSS had been taken over by Oslo Municipality and merged to become Oslo Sporveier. However, the two municipalities and their tram companies could not agree on terms to lease the trackage from Etterstad to the city center. Part of the problem was the lack of a suitable turning loop with free capacity in the city center. Instead, Akersbanerne decided to operate the trams to Etterstad, where there would be transfer, without transfer tickets, between the two tram companies. For the operations, Akersbanerne bought four Class A trams and three trailers, which were built by Skabo Jernbanevognfabrikk and delivered in 1926 and 1927. This was not sufficient to operate all the lines, so an addition three trams were leased from Ekebergbanen.