Machynlleth is the location where the majority of eastbound or 'up' trains from and combine to go forward as one towards and . Similarly, most trains in the opposite direction divide here before continuing west. The service in each direction is approximately two hourly, although trains to Pwllheli are far less frequent on Sundays. The infrastructure along the line was upgraded during 2010/11, with the intention of allowing hourly trains to and from Aberystwyth. In the 2015-16 timetable, some additional Shrewsbury - Aberystwyth services operate to give an hourly interval frequency during the morning & evening peak periods.