Millions of rail users in the UK are bracing themselves for news of an increase in regulated rail fares from January 2018.
Train operators are allowed to raise fares by as much as the Retail Prices Index (RPI) figure for July, expected to be in the region of 3.5%.
The exact figure will be published later this morning.
Passenger groups said commuters would be worst-hit, and suggested that the RPI measure should be scrapped.
The rises will affect “anytime” and some off-peak fares as well as season tickets in England and Wales.
In Scotland, it is mainly commuters who will be affected, with off-peak fares rising by a smaller amount.
The Scottish government currently limits rises in off-peak fares to RPI minus 1%.
There are no plans for increases in Northern Ireland.
Unregulated fares, which include super off-peak travel and advance tickets, will be set in December.
Transport Focus, which represents the interests of passengers, said rail users were already fed up with getting poor value for money.
“Wages are not keeping pace with inflation and performance remains patchy,” said a spokesperson for the group.
“Passengers, especially commuters, face potential strike action, the consequences of the continual rise in passenger numbers, and disruption caused by railway upgrades.”
Transport Focus said it would also like to see the RPI measure replaced by the Consumer Prices Index (CPI), which is currently running at 2.6%.
CPI is typically lower than RPI.