Ridership continued to grow, especially after World War I started, and there was more money around. In 1915, five additional Class 2 trams were bought. In 1919, the company had 13.9 million passengers. In 1918, eight used horse-cars were bought from Oslo Sporveier and rebuilt to electric trailers and to metre gauge. Ten new trams of Class 3 were delivered in 1922. To create enough overnight space for all the new trams, a third depot was built at Dalsenget, and the Elgeseter Line extended there in 1923. New turning loops were also built at Ilevolden and Voldsminde in 1921. The passing loops at the railway station was built in 1928, and at Dalsenget in 1949. Bakke Bridge was rebuilt in 1928 so the last part of the Lademoen Line had double track.