Near the intermediate Spiez station, the Lake Thun line has junctions with two further lines owned by the BLS AG; the Spiez–Erlenbach–Zweisimmen line from Zweisimmen and the Lötschberg line to Brig.
Whereas tracks 4 and 7 are used by regional traffic to and from Fontanivent, Sonzier and Les Avants, tracks 5 and 6 are for trains to and from Zweisimmen.