At the time, the branch to Grimstad was being planned built as a private railway, and from Messel to Blakstad the Messel route and the Grimstad Line would follow the same right-of-way.
Pada saat itu percabangan menuju Grimstad direncanakan dibangun sebagai jalur kereta api swasta, dan dari Messel menuju Blakstad, rute Messel dan Jalur Grimstad akan bersebelahan.