By Jonathan Davies
Rail fares have risen three times faster than wages over the past five years, according to the TUC.
The union's study found that rail fares have risen 25% between 2010 and 2015. By comparison, wages have risen just 9%.
The report comes ahead of inflation data released today (Tuesday). Inflation is used to calculate rail fare increases.
Some campaigners, particularly rail unions, are calling for the UK's rail networks to be brought back into public ownership. Many believe the public sector would be able to cut rail prices.
The government has already said that regulated fares, which account for roughly half of all tickets sold, in England will not rise by more than inflation during this parliament.
In the final two years of the coalition government, rail fare increases were limited to inflation as measured by the retail prices index (RPI), which is typically higher than the official rate of inflation as measured by the consumer prices index.
TUC director general Frances O'Grady said commuters are being left "seriously out of pocket" by the price rises over the past five years.
"If ministers really want to help hard-pressed commuters they need to return services to the public sector," she said.
"It would allow much bigger savings to be passed onto passengers."
Action for Rail - a campaign led by the TUC and rail unions - believes as much as £1.5 billion could be saved over the next five years by bringing rail networks back into public ownership, particularly the Northern, Transpennine and West Coast Main Line.