Great Western Railway (GWR) has issued advice to its passengers about its new timetable and festive season travel arrangements.

Along with other operators, GWR will introduce a new timetable on Sunday, 14 December. It is making changes to timetables on many of its services, which it says are “designed to respond to changes in demand and improve service performance”. The operator is asking its passengers to check their journey times ahead of the changes.

GWR is also urging passengers to book ahead and reserve seats for journeys during the upcoming festive period, and points out that its journey planners are up to date with Christmas and New Year information, and Advance fares are already on sale on its website.

When the timetable changes, GWR will withdraw its three remaining Castle Class sets from service. They are now nearly fifty years old, and their final journeys will be on Saturday, 13 December.

The Castle Class trains have been running on local routes between Plymouth and Penzance. GWR will replace them with trains from its existing fleet. It will also deploy its recommissioned Class 175s to replace the Castle Class trains. These previously operated in Wales, and when they return to service, will be maintained by Alstom.

Repairs and improvements are scheduled across GWR’s network over the Christmas and New Year period, but disruption will be less than in previous years.

Between Saturday 27 December and Sunday 4 January, track renewal work will affect some services to and from London Paddington, with no direct services between Paddington and Cheltenham Spa.

Upgrade work to the west of Cardiff Central station between Wednesday 24 and Wednesday 31 December will mean that some tracks will close and trains will be diverted between Cardiff Central and Bridgend via Ninian Park (not stopping at Ninian Park). This will add a few minutes to journey times.

GWR is advising passengers that when booking their journeys, they can avoid busy trains by travelling early and avoiding services that depart between 10:00 and 14:00. It predicts that its services will be at their busiest on Monday 22 and Tuesday 23 December, and Saturday 27 and Sunday 28 December.

It is also reminding passengers that rail services shut down earlier than usual on Christmas Eve, and that, as usual, no train services will run on Christmas Day or Boxing Day.

GWR has also issued advice about luggage. While stressing that there is plenty of room for cabin-style hand luggage, laptop bags, and handbags in the overhead racks and under seats, it warns that there is limited space for larger and standard suitcases and bags (up to 25 x 40 x 75 cm) on each carriage’s luggage rack. It is asking passengers not to bring more than three items of luggage or anything they cannot carry or easily move around.