An internal investigation by the Slovenian Railways has pinpointed human error as the cause of the 21 December accident in which two rail workers were killed just south of Postojna.

Matjaž Kranjc, the head of the infrastructure arm of the rail operator, told reporters on 22 January that all devices had functioned properly and that human error was entirely to blame.

The investigation found that the track signalman had failed to inform the maintenance crew that a passenger train was approaching, while the crew warden should have consulted the train schedule.

"The train was running four minutes late and the crew had even been talking that a train was bound to come any minute. They were relying on the signalman to inform them. The warden made a mistake for not strictly relying on the schedule."

Ultimately, the warden was the one who spotted the oncoming train and alerted the crew, said Kranjc, adding that he had likely prevented even more casualties. "But fact remains that he should have called the centre and find out why the train had not yet left the Postojna station."

The train driver signalled the crew three times, Kranjc said; however the track configuration, which includes a number of bends, and working machinery meant that the crew's safety setup had not been optimal.

The investigation also found that the signalman had been using a work phone for personal purposes during the incident. Kranjc said Slovenian Railways had issued a ban on any "elements" that might disturb the signalmen.

Complaints raised by workers

Meanwhile, the public broadcaster RTV Slovenija reported that workers, including one of the casualties, had warned their superiors about the signalman in charge being unreliable. The newspaper Dnevnik reported that the signalman had been fined in 2017 over an error. The two victims were related, with one being the father-in-law to the other.

Slovenian Railways CEO Dušan Mes denied there having been any complaints about the signalman or anybody else at the Postojna train station. He said the court found no fault on the part of the signalman in the 2017 accident.

The track warden has been suspended, the signalman is being terminated and six members of the crew remain on sick leave, Kranjc said.

Two other investigations into the accident are ongoing: an investigation by the Infrastructure Ministry is due to be completed in March, while the police are conducting their own investigation.

In the month since the accident, Slovenian Railways made a number of safety procedures that had been advisable before the tragic incident mandatory.

RTV Slovenija's web portal said there had been a total of five rail accidents in which rail workers were injured or died in the past ten years, three of them taking place last year.

Mes said the signalling and safety device used was one of the best and most modern in the world. The company is now also considering additional technical precautionary equipment, but experience abroad is mixed, as workers tend to rely too heavily on them.