Engineering work is taking place in the early morning between Bridgend and Baglan, closing some lines.
As a result, the 07:55 Swansea to London Paddington service will start from Cardiff Central.
A replacement bus service will run direct from Swansea to Cardiff Central, departing earlier than usual at 07:50.
A second replacement bus service will run between Swansea and Cardiff Central calling at Neath, Port Talbot Parkway and Bridgend, departing at 07:35.
Check before you travel:
You can plan your journey using the National Rail Enquiries Journey Planner
Replacement Bus Travel Advice:
For helpful advice if you need to travel on a rail replacement service, including accessibility information, please use our travel information pages.
You can find the location of your replacement bus by checking station signs or by searching for your station on our station information pages.
Please be advised that replacement vehicles may be busier than usual, and you should allow extra time for your journey.