Most services are run by Arriva Trains Wales, who run an hourly service from Manchester Piccadilly to Carmarthen calling at Llanelli and Burry Port. This service is extended to Milford Haven every two hours. There is also a two hourly service from Swansea to Pembroke Dock calling at all stations. The Fishguard Harbour branch has two trains per day to connect with ferry services to Rosslare, Ireland. First Great Western also run at least one train per day from London Paddington to Carmarthen. On summer Saturdays, two trains run from London Paddington to Pembroke Dock. The first up service calls at all stations from Llanelli to Pembroke Dock whilst calling at selected stops on the down service. The second up service calls at the selected stations to Pembroke whilst calling at all stations to Llanelli on the down service.
The majority of usage of the west Wales line is from Swansea, Llanelli and Carmarthen, the other stations accounting only for a small percentage of journeys. Most rail users drive to one of the major stations (Haverfordwest, Carmarthen, Llanelli) rather than use the smaller stops. Although there is some communting, traffic west of Tenby and Haverfordwest is very seasonal and includes tourism. Local government is currently proposing to increase the tourist potential of the services. Passenger usage in South Wales has grown by 11.4% between 2001 and 2004, and this trend is expected to continue.
Historically the line carried a great deal of heavy freight traffic. With the run down of coal and other heavy industry this has fallen dramatically. Nevertheless large amounts of freight continue to be moved. Recent developments have included facilities at Fishguard Harbour and Tre Cwn for sending intermodal traffic from Ireland direct via rail.
SWWITCH is currently performing a business case review of the Fishguard branch, and whether it is viable to continue to operate a passenger service. The results of this may lead to the withdrawal of services from Fishguard, or their improvement.
A early stage feasibility study is being undertaken by the Welsh Assembly Government with Network rail for the re-doubling of the section between Llandelio Junction and Cockett. This would permit more trains to stop at Gowerton, (in particular Heart of Wales trains) and to enable an increase in the number of trains over this section.
Also under consideration by WAG is changing the status of the Pembroke Dock branch to a community railway and possibly then using light-rail or tram/train vehicles to provide a better and more cost effective service. Currently it is not clear how any such changes would be funded and Network Rail have no plans to perform them.
Plans are under consideration (by Pembrokeshire County Council) for a new deepwater road/rail intermodal port at Milford Haven.