The Rail, Maritime and Transport union (RMT) is warning of further industrial action as the bitter row approaches its third year.
The warning comes before a 24-hour strike on Saturday by RMT members on Arriva Rail North (Northern) and on South Western Railway on New Year’s Eve.
Services on both days will be disrupted, with buses replacing trains on some routes.
It will be the 42nd strike on Northern, with stoppages planned on every Saturday in January.
RMT general secretary Mick Cash said: “Throughout 2018, RMT members have fought for the principles of a publicly owned, safe and accessible transport network for all.
“In 2019, we will be stepping up that campaign as the Tory Government teeters on the brink and the prospect of sweeping away years of private greed and austerity grows by the day.
“I want to pay particular tribute to RMT members on Northern and South Western Railway, who will be striking again this weekend and on New Year’s Eve in a long-running battle to put public safety before private profit.
“They are a credit to the entire trade union movement.
“We have major pay campaigns looming large on our agenda early in the new year, notably on Network Rail and London Underground, and the union has made it absolutely clear that we will not accept any attempt to undermine our members’ standard of living and that we will fight to ensure that those standards are both protected and enhanced.
“From the railways to the offshore and shipping industry and through to the buses and road transport, RMT has fought against a tide of cuts, privatisation and for the principles of workplace justice for all.
“That fight will ratchet up as we head into the new year.”
Northern has called for an independent inquiry into the dispute in a bid to break the deadlock.
Managing director David Brown said: “More than 50% of all rail journeys in the UK are made on driver-controlled trains and recently the Department for Transport and Transport for the North publicly confirmed that a second person - in addition to the driver - would be retained on Northern services.
“This second person will provide customer service, including meeting customer needs on accessibility, safety, security, ticketing and information.
“Therefore, there is no reason for the RMT to continue its disruptive and economically damaging strikes but despite this, the RMT continues with its strike action.”
Northern said it has promised conductors their future role will be on-board trains, guaranteeing that role until at least 2025, their current pay will be protected - the starting salary for conductors is £28,250 - and that it will be reviewed annually if RMT ends the dispute.