Commuters from regional Victoria are set to face significant delays getting into Melbourne as V/Line workers press ahead with a strike.
The Rail, Tram and Bus Union on Tuesday confirmed workers were going ahead with a whole of network strike on Wednesday, with passenger trains expected not to run between 3am and about 8am.
Union secretary Vik Sharma said it had made itself available for intensive negotiations since threatening strike action more than a week ago, but V/Line refused to address members' claims.
"We've been negotiating with V/Line for over six months. We made our claims clear to them on day one and they've refused to address them," Mr Sharma told reporters.
"Our members are fighting for job security and (better) conditions.
"This fight is about making sure that we secure the rail jobs for the future."
Ticketless technology posed a serious risk to V/Line jobs, and the regional operator wanted to split a full-time job into two part-time jobs and give each eight-hour weekly contracts, Mr Sharma said.
The union wanted to safeguard against those changes and align the workforce with technological changes, he said.
"We have been negotiating in good faith and remain hopeful that an agreement can be reached soon but if V/Line refuses to budge, then we won't hesitate to keep the fight on," Mr Sharma said.
"Our members don't simply just sell tickets, they do much more than that and that needs to be recognised and respected."
V/Line chief executive Matt Carrick said the strike would disrupt tens of thousands of passengers.
"We have been negotiating with employee representatives and the union in good faith and urge the union to reconsider this action," Mr Carrick said in a statement.
"We'll continue to work with the union to deliver excellent employment conditions for our workforce and a great service for our passengers - we will work hard to minimise the impacts of disruption on passengers."
V/Line advised commuters to avoid travelling in the morning and said a very limited coach replacement service would operate, but with significant delays expected.
Coaches would not stop at any metropolitan stations and delays and cancellations would continue throughout Wednesday, the operator said.
