Relatives of the 57 people who died in Greece's worst ever train disaster crowded into a courtroom on Wednesday, demanding justice for the victims.
The trial had already been postponed once because of the chaotic start last week.
Most of the victims of the crash three years ago were students, killed when their intercity service from Athens to Thessaloniki smashed head-on into a goods train on the same line near Tempi in the centre of the country.
Some of the victims are thought to have burnt to death after surviving the initial collision.
Many relatives were unable to get into the courtroom in the central town of Larisa last week, and the situation was little different when it resumed on Wednesday.
Police officers allowed in only participants who were legally scheduled to attend.
Some relatives complained that two rows of seats had been taken up by police, while others said they still could not witness proceedings clearly enough.
Defence lawyer Zoe Konstantopoulou appealed for the proceedings to be filmed as access for families had been restricted.
The February 2023 disaster is widely known in Greece as the Tempi crime - with many arguing it encapsulates negligence and corruption at the heart of the state.
Thirty-six people are on trial in a case that is expected to hear from 350 witnesses and set to last years.
Maria Karystianou, who lost her 19-year-old daughter Marthi, said relatives had been packed like sardines in the courtroom, describing the situation as an absolute disgrace.
The railway network had not made use of EU funding intended to improve safety. The head of the European Public Prosecutor's Office, Laura Kovesi, later said the collision could have been avoided if the money had been spent on modernising the signalling system in time.
This disaster provoked widespread anger and protest across Greece.
Despite the public outcry, Prime Minister Kyriakos Mitsotakis was re-elected soon after the disaster and has survived two related no-confidence votes in parliament.
