Whitland crash: Buses replace trains west of Carmarthen
Buses will continue to replace trains west of Carmarthen as work goes on to reopen the track after a train hit a lorry on a crossing near Whitland.
Seven people on Monday's 09:10 Milford Haven to Manchester service received minor injuries in the collision.
The 48-year-old lorry driver from Llanboidy was arrested on suspicion of endangering safety.
Network Rail said engineers were working to restore services to normal as soon as possible.
The Arriva Trains Wales (ATW) train hit the stationary hay lorry at Llanboidy level crossing on a minor road near a spot called Crossing Cottage at about 09:50 GMT on Monday.
There were just under 60 passengers on board.
Five needed hospital treatment.
British Transport Police and the Office of Rail Regulation are investigating how the crash occurred.
The 48-year-old lorry driver was arrested on Monday afternoon and questioned at Haverfordwest Police Station.