 In 1927, the Sørland Line was extended to Neslandsvatn and received a temporary terminus at Kragerø via the Kragerø Line.The next stage of the line was the extension from Neslandsvatn to Nelaug, where it would connect to the Arendal Line and use it to reach the coast.In preparation for the arrival, NSB had in 1923 proposed to convert the Treungen and Grimstad Lines to standard gauge.