Some train passengers could face season ticket fare rises of more than 5% under new year increases expected to be announced tomorrow.
Recent Government announcements have meant the annual rise in regulated fares, which include season tickets, will not be so severe for 2014.
But the new price-rise formula, which will kick in on January 2, still allows for average regulated fare increases of 3.1%.
And train companies can use a 2.0% "flex" regulation which lets them put some regulated fares up by 5.1% as long as their overall average does not exceed 3.1%.
The increase for any January is calculated from the RPI rate of inflation figure for the previous July. In July this year the RPI figure was 3.1%.
Campaign for Better Transport chief executive Stephen Joseph said: "We're very disappointed that the higher RPI figure is still being used when it comes to passengers having to find money for their annual increase.
"Yet when it comes to pensions and other benefits, the lower CPI inflation figure is used."
The announcement of the rise has been delayed this year after Chancellor George Osborne announced in his Autumn Statement earlier this month that the increase formula for regulated fares was changing from RPI plus 1% to RPI plus 0%.
Earlier the Government had also announced that the "flex" rule, which originally allowed companies to put up some fares by up to 5% above the RPI plus 1% figure, would be limited to 2% above.
Before these changes, some passengers could have faced season ticket rises of as much as 9%. However, even with the new formula, many passengers will be finding their fare rise far outstripping their wage rise.
Some passengers might have to wait a few more days to find out what their January rise will be as it is thought that some train companies may not yet be ready to announce the new fares.
Mr Joseph said: "Passengers will see season tickets going up three times faster than their wages. The Government needs to do more to stop the squeeze on commuters and avoid pricing people off the railways. We need a permanent end to inflation-busting fare rises calculated using an out-of-date formula."
He went on: "The Government should stop using RPI to calculate ticket prices. It over-estimates real inflation so consistently that the Office for National Statistics has dropped it as an official measure.
"The Government has already switched to CPI for most things. Doing the same for train fares would have little impact on railway revenues, but it would save passengers money and bring fares into line with things like public sector pensions."
Bob Crow, general secretary of transport union the RMT, said: "2014 is all set to be another year of racketeering and greed on Britain's privatised railways.
"Passengers will continue to pay the highest fares in Europe to travel on creaking, overcrowded trains where even raw sewage is dumped on the tracks because the private operators will not stump up for tanks and the staff to empty them. That is a sickening indictment on our privatised railways as we head towards the new year.
"The only solution, and one that's opposed by all our main political parties, is total renationalisation and the return of our railways to the ethos of public service under complete public control."
A Department for Transport spokeswoman said: "The Government understands concerns rail passengers have about the costs of fares and the impact they have on household budgets.
"That is why next year, for the first time in a decade, regulated fares will not rise on average by more than the rate of inflation, offering relief for families and the hardworking people."
She went on: "As well as protecting regulated fares the Government is driving forward the biggest programme of rail modernisation programmes ever, with £38 billion being invested over the next five years.
"That means new state-of-the-art trains, better stations and hundreds of miles of electrified track which will help cut journey times, provide better connections and stimulate growth across the country."