The Association of Train Operating Companies (Atoc) has said the overall average rise, including non-season tickets, will be 3.9% on Wednesday, with some fares not going up as much as this.
But with some non-season-ticket unregulated fares allowed to be increased by an unlimited amount, Railfuture said that some fares could be going up by around 11% or 12%.
From Wednesday, fares are also going up by an average of 4.2% on the Underground and on London buses.
Petrol tax is frozen and overall the cost of driving remains static. How does this help persuade people out of their cars and ease congestion? Where is the green policy?
More top news
The school holidays and people heading off on their summer breaks have boosted the total to a record 8,800 flights in 24 hours.
At least two people have died and more than 120 others have been injured after an earthquake rocked Turkey and the Greek island of Kos.
Friday morning's forecast for the west of the region