The expert on the train accident in Spain: "Similar system in Sweden"

On the recordings, the traffic control can be heard giving the high-speed train permission to continue at full speed even though the safety system had stopped working. And it was not stopped even though the driver of the stationary train announced that it was still stationary.

Five minutes after the last call, the trains collided.

- It must be a human error. The decisive factor is the traffic control's message to the driver of the overtaking train to increase to full speed, says Oskar Fröidh, director of the Railway Group at the Royal Institute of Technology.

The Swedish expert: "The train conductor has made a mistake"

Oskar Fröidh has listened to the conversation and analyzed the course of events on behalf of SVT. He sees the fact that a single incorrect order can have such catastrophic consequences as a system error.

- There can be a fault in the signaling system and then the procedures for handling it must be very strict. In this case, it seems that the train conductor has made a mistake, he says and continues:

- But there must be support from the train conductors to be able to handle this type of disturbance, both in terms of stress and safety.

"There are no guarantees"

A question that many Swedes ask themselves is whether an accident like this can also happen in Sweden?

- There are no guarantees that it can't happen as we basically have the same functionality - our signaling system can also go down and then the train conductors get a lot of responsibility, says Oskar Fröidh and continues:

- In Sweden, we have fairly strict rules regarding safety and that is good. But in general, the train conductors must get more support because problems occur even here in Sweden.

The accident has sparked anger in Spain and on Wednesday protesters clashed with Spanish police in Madrid.

Hear the conversation between the train conductor and the train driver in the clip above. There, Oskar Fröidh analyzes the accident.