The line was extended to Åmli on 17 December 1910 and to Treungen on 14 December 1913, and was named the Arendal–Treungen Line.
Jalur diperpanjang hingga Åmli pada 17 Desember 1910 dan menuju Treungen pada 14 Desember 1913, dan namanya diganti menjadi Arendal–Treungenlinjen.