More than 300,000 extra seats will be introduced on trains running across the Wales/England border.
Improvements will be introduced on the Arriva Trains Wales network with the timetable change on May 14.
The company said it is responding to continued growth in passenger numbers by increasing the number of carriages and seats available on trains as well as providing some new/extended services.
Extra seats will be provided betweenShrewsbury, Telford andBirminghamin the morning commuter period, and betweenBirminghamand Aberystwyth in the mid-morning period.
There will be extra seats and extra services betweenChesterto Llandudno Junction in the mid-afternoon and evening commuter period.
More services are also planned between West Wales,SwanseaandCardiff, as well as improved connections with ferry services fromIrelandat Holyhead.
ATW is gearing up to provide increased capacity for Olympic events inCardiffand the Royal Welsh Show at Builth Wales, which overlap this summer.
Mike Bagshaw, Commercial Director at Arriva Trains Wales, said: “In excess of 340,000 extra seats a year will be provided in response to rising customer demand, reflecting a significant investment by Arriva in the future of rail services throughout Wales and the English Borders”.
For more information, go to www.arrivatrainswales.co.uk