ScotRail passengers may be travelling free on strike days because stand-in conductors are not checking tickets, The Scotsman has learned.
The revelation came as travellers face a 12th strike on Sunday, with further walkouts to be announced shortly.
The train operator admitted managers and other workers drafted in to take the place of striking conductors were just doing “operational” duties.
Conductors, or guards, normally check tickets on board trains as there are no ticket gates or checks at most ScotRail stations.
However, during the industrial action, those performing the role focus on opening and closing doors and looking after the safety of the train.
There are ticket gates at 16 of ScotRail busiest stations, and staff checks have been stepped up at others during the strike. But this has left other lines where trains have run on strike days with no ticket checks.
These include at most stations on the Borders Railway, and between Edinburgh and Fife and North Berwick.
Also, some stations between Edinburgh and Dunblane, and between the Central Belt and Aberdeen and Inverness.
Other examples include stations between Glasgow and East Kilbride and Kilmarnock.
Stations on the main Edinburgh-Glasgow line all have ticket checks at peak hours.
Most other trains in and around Glasgow, which have ticket examiners rather than conductors on board, are unaffected by the dispute.
RMT Scottish organiser Mick Hogg said ScotRail must be losing an “absolute fortune” from the lack of ticket checks and cancelled trains – about one in five of services.
He said: “There will be more strikes, subject to approval by the union’s national executive. We will be announcing additional dates pretty soon.”
A ScotRail spokeswoman said: “Our priority on strike days is to help customers get where they need to go. To do this, the temporary conductors are focused solely on operational responsibilities.
“We have additional staff at our busiest stations to assist customers who may require to purchase tickets.
“We’re satisfied we’re doing all we can to keep ticketless travel to a minimum under the circumstances.”
ScotRail said it sought to cut fare dodging, or “ticketless travel”, with more and easier-to-use station ticket machines, and extra ticket gates.