Talks to avoid fresh strikes by Merseyrail workers over driver-only operated trains have ended without agreement.
The union, which says it wants to keep guards on trains for public safety, said strikes were “inevitable”.
Merseyrail said it wanted the RMT to back the decision for the new “safer” operating system.
Merseyrail managing director Jan Chaudhry-van der Velde earlier said he wanted to avert strikes which would be “damaging” to customers and the economy, particularly during next month’s Grand National, when, he said, the “eyes of the world will be on Liverpool”.
Coinciding a strike with the race meeting would be “detrimental to the city region’s reputation” he said, adding he “sincerely” hoped the RMT would not consider striking then.
The RMT’s John Tilley said industrial action was now “inevitable”.
Up to 2,000 union members from Merseyrail, Northern and Southern rail took part in the strikes on 13 March and some drivers chose not to cross picket lines.
RMT members on Southern rail network are to stage another strike on 4 April.