Improvements worth �10m will be made on train lines between Shrewsbury and Aberystwyth over the next two years. Work will be carried out on the Cambrian lines, west of Shrewsbury.
The work will mean an increase in trains' speeds and frequency - there will be an hourly service as opposed to one every two hours.
A working group made up of Arriva Trains Wales, Network Rail and the Welsh Assembly, was set up to oversee the improvements.