 To being with, a steam locomotive was stationed at Grimstad, but in 1938 it was replaced with a multiple unit.The line was transferred from Arendal District to Kristiansand District when the Sørland Line was opened to Kristiansand from 21 June 1938.In 1939, the Grimstad Line had an operating loss of NOK 90,000, and NSB made an inspection to consider closing the line.