Platform one on the western side of the station is separated from the other two by the ferry terminal buildings and inner harbour and is the one normally used by Avanti West Coast services to London Euston. Most Transport for Wales DMU services use platform two. Platform three is outside the train shed and is used by the early morning "Premier Service" to Cardiff Central, plus a few other trains at busy periods. There are carriage sidings and servicing facilities alongside platform one, whilst platform three also has an engine release line & run-round loop available.