- Video report by ITV News Consumer Editor Chris Choi
The cost of regulated rail fares, including season tickets, will soar by 3.6% next year - the biggest rise in four years.
The confirmation of 2018's rise, which compares to this year's 1.9% increase, comes on a day of major transport disruption after a train derailment at London Waterloo station.
A leading rail union estimates the 3.6% hike will bring a minimum £337 million more revenue for the train operating companies.
Rail workers are staging a series of protests warning passengers they are paying "more for less".
Why are passengers paying so much?
It has been the policy of successive governments to reduce the funding of the railways by taxpayers and increase the relative contribution of passengers.
The annual January rise in regulated fares - almost half of all tickets and including season tickets and standard returns - is linked with the previous July's Retail Price Index (RPI) measure of inflation.
The Office for National Statistics (ONS) confirmed the July rate at 3.6%, which means the 2018 hike in fares will be the biggest annual rise since 2013.
Is there an alternative?
Public transport campaigners have called for the government to use the Consumer Price Index (CPI) measure of inflation to set rail fares, which is generally lower than RPI and is used to calculate changes in benefits.
July's CPI figure remained unchanged at 2.6%.
The ONS warned last month that RPI is "flawed" and has "serious shortcomings" while rail campaigners said it was "unacceptable" to still use it.
Stephen Joseph, chief executive of Campaign for Better Transport, said: "Passengers would be forgiven for thinking they are being taken for a ride when RPI has been dropped as an official measure for most other things.
"We want the Government to commit to changing the way it calculates future fare increases and start using the Consumer Price Index (CPI) instead so that rises more accurately reflect real inflation and ensure rail travel remains affordable for all."
The campaigners and Mayor of London Sadiq Khan have called on the government to freeze fares in January.
What are the protesting rail unions arguing?
Rail unions said, even as fares rise, rail engineering work is being delayed or cancelled, skilled jobs are being lost and staff are being cut on trains, stations and ticket offices.
They will call for reduced fares, public ownership and protection of jobs, during protests on Tuesday outside railway stations across the country, including London, Birmingham, Cardiff, Bristol, Glasgow, Manchester and Liverpool.
Transport Salaried Staffs Association leader Manuel Cortes said: "When the Tories passed legislation which allowed rail fare hikes year in, year out, they made legal one of the greatest train robberies in railway history.
"Dick Turpin had the decency to wear a mask when he robbed his passengers. Today train companies, with the Government's blessing, hide behind the Retail Price Index as a method of legitimately fleecing more money from hard-pressed passengers at the start of each new year."
What has the government said in response?
A Department for Transport spokesman the government has "always fairly balanced the cost of this investment between the taxpayer and the passenger".
He added: "The Government carefully monitors how rail fares and average earnings change, and keeps under review the way fare levels are calculated.
"Regulated rail fares are capped in line with inflation for next year. In the five years to 2019, Network Rail is spending more than £40 billion to maintain and improve the network."
He said 97p from every £1 of a passenger's fare is invested in the railway during the "biggest rail modernisation programme for over a century".