The Tretten train disaster occurred on 22 February 1975 when a northbound train (no. 351) from Oslo and a southbound express train (no. 404) from Trondheim collided one kilometer north of Tretten station. With 27 killed and 25 injured it was the worst train crash in Norwegian peacetime history. One of the victims came from the United States, the rest were Norwegian. Altogether there were around 800 passengers on the two trains. The cause of the collision was that the northbound train left Tretten station when it should not have.

The accident has some similarities with the Åsta accident. The stretch of track was controlled remotely but had no automatic stopping mechanism, and the direct cause on both occasions was trains allegedly passing stop signals.

In July 1969 another accident of the same type occurred near Straumsnes on the Ofotbanen. Two trains carrying iron ore collided and a driver's assistant was killed.