Rail fares have risen twice as much as pay since 2010, according to new research ahead of news tomorrow on how much prices are set to increase next year.
Analysis by the Rail, Maritime and Transport (RMT) union found rail fares have risen 32 per cent in eight years, while average weekly earnings have increased 16 per cent in that time.
Using the example of a new nurse or police officer commuting from Chelmsford to London, where annual season tickets would cost £4,000 after the latest rise, the RMT said such individuals would pay 20 per cent of their salary for an annual season ticket.
RMT general secretary Mick Cash said:
The private operators and government say the rises are necessary to fund investment but the reality is that they are pocketing the profits while passengers are paying more for less with rail engineering work being delayed or cancelled, skilled railway jobs being lost and staff cut on trains, stations and at ticket offices.
The government links the annual January rise in Britain's regulated fares with the previous July's retail price index measure of inflation (RPI), which is announced by the Office for National Statistics.
Regulated fares account for nearly half of all tickets, and include season tickets as well as standard returns. They rose by 1.9 per cent in January, but the RPI figure for this July is expected to be well over three per cent.
In July earnings grew by two per cent, while inflation was at 2.6 per cent.
Research from the Trades Union Congress (TUC) in January found UK commuters spent up to six times as much of their salary on rail fares as other European passengers.
TUC general secretary Frances O'Grady said it was "grim news for commuters, who are facing another year of fare hikes".
The Department for Transport said the government "carefully monitors how rail fares and average earnings change, and keeps under review the way fare levels are calculated".
A spokesperson said: "We are investing in the biggest rail modernisation programme for over a century to improve services for passengers - providing faster and better trains with more seats.
"We have always fairly balanced the cost of this investment between the taxpayer and the passenger. We are driving the industry hard to improve efficiency to ensure we maximise the value of passengers' and taxpayers' investment in the railways.
"Regulated rail fares are capped in line with inflation for next year."