An estimated 900,000 rail journeys each year in Scotland are made by people who deliberately avoid paying their fare, according to a train operator.
ScotRail revealed the figure as it launched a crackdown on fare dodgers.
Its new Buy Before You Board campaign is aimed at encouraging customers to purchase their tickets before getting on the train.
Phil Campbell, ScotRail’s head of revenue protection, said: “We provide a service and it’s only fair that everyone pays the correct fare for the service they use.”
The company said a recent ticket-monitoring exercise revealed that 132 people had travelled without a ticket on 10 services they examined.
Some 450 flexible journey tickets were found to be used incorrectly during four days of monitoring at Glasgow Queen Street station.
Elsewhere, at Glasgow Central station, 19 customers declared a shorter journey than the one they had actually travelled during one morning peak-time focus on the East Kilbride and Barrhead lines. That dodge is the most common form of fraudulent travel, according to the train operator.
ScotRail is taking action to tackle premeditated fare fraud, saying its surveys show that honest passengers are frustrated by fare dodging.
Other analysis suggests customers are fed-up with long queues in peak times at major stations.
The firm said it has invested in ticket vending machines at 26 new sites and is upgrading the machines at a further 100 sites to help customers buy their tickets in advance.
There are now 260 machines across the network, with 20 more to be installed by the end of the year.
Mr Campbell added: “We’ve invested heavily in facilities to make it much easier for our customers to buy tickets in advance. This means that staff on trains have more time to help customers with travel or other queries.
“Buying before boarding will result in much shorter queues to get through the gates at busy destination stations such as Glasgow Central.”
