The accident is probably due to one of the drivers having missed a stop signal, Kristian Madsen says, a railway expert at the Danish Engineering Association IDA.
He points out that both trains were on the single-track route at the same time.
"What happened here is that one of the trains passed a station where there was a stop signal and moved onto a section of track before the other train entered the station. Suddenly you have two trains on the same section," he tells the newspaper Berlingske.
Preben S Pedersen, from the Danish Railways Union, tells BT that there is no radio-based safety system on the route.
"The route is completely manual, and therefore it is entirely dependent on the decisions of the train drivers and on the signals working perfectly," he says.
Katarina Bjurman, an investigator at the Swedish Transport Agency, notes that train collisions on routes with fully developed signaling and alarm systems are unusual. On those routes, trains are automatically braked when two trains are on the same track in opposite directions. Accidents are more common on smaller routes:
"On those routes you don't have many electronic systems in place to help control this. Everything is then based on the driver being in constant contact with the train dispatcher."
