Thousands of workers walked off the job on Wednesday to protest over Greece's deadliest train disaster that killed 57 people, with mass demonstrations expected to culminate outside parliament in Athens at midday.
The crash on Feb. 28 has stirred public outrage over the crumbling state of the Greek rail network, and striking workers say years of neglect, underinvestment and understaffing - a legacy of Greece's decade-long debt crisis - are to blame.
Many of the around 350 people aboard an intercity passenger train that collided head-on with a freight train while travelling on the same track were university students heading to the northern city of Thessaloniki from Athens after a long public holiday weekend.
The disaster has sparked protests across Greece with more than 10,000 rallying in Athens on Sunday, releasing hundreds of black balloons into the sky.
Rail workers have staged rolling, 24-hour strikes since Thursday, bringing the network to a halt. They say their demands for improvement in safety protocols have gone unheard for years.
ADEDY, the umbrella union representing hundreds of thousands of public sector workers, has also called for a 24-hour walkout.
"We will impose safe railways so that no one will ever experience the tragic accident at Tempi ever again," the main railway workers union said in a statement.
"We have an obligation towards our fellow humans and our colleagues who were lost in the tragic accident."
Other transport workers walked off the job in solidarity, disrupting metro, tram and bus services in the capital Athens. Ships also remained docked at ports as seamen participated in the labour action.
Students and teacher groups have said they will take part in the rallies expected around midday in central Athens. They want authorities to thorougly investigate the causes of the accident.
"It's not the time to fall silent, it's time to speak up and fight," a teachers' union said in a statement.
Greece sold its state-owned railway operator, now called Hellenic Train, under its international bailout program in 2017 to Italy's state-owned Ferrovie dello Stato Italiane.
The government, whose term expires this summer, has blamed human error for the crash. Prime Minister Kyriakos Mitsotakis apologised on Sunday, acknowledging decades of neglect could have contributed to the disaster.
Hours after the crash, his transport minister resigned. Mitsotakis handed the portfolio to one of his closest aides, state minister George Gerapetritis.
On Wednesday, Gerapetritis was expected to meet transport experts from the European Commission, which has promised support, and make statements to the press after a two-day inspection at the crash site.