during the 1960s, the gråkallen line experienced a large ridership increase from the halset area. from 1956 to 1971, halset was built out with large apartment blocks. these were the only apartment blocks along the line, as most of the route was along housing. by 1970 there were 10,500 people living along the line, and half of them were in the munkvoll/halset area. graakalbanen suggested building a loop around halset; from munkvoll, it would follow selsbakkveien, allette beyers vei, a. andreassens vei and back into the gråkallen line at rognheim. total distance would be , and would cost nok 1.5 million. ridership was estimated to increase to 1.2 million.