Great Western Railway has announced it has been forced to cancel 'a small number' of its train services over the Christmas period due to a coronavirus outbreak among staff.
Around 50 GWR workers from Plymouth and Penzance are currently self isolating after several train crew tested positive for Covid-19.
GWR said it will run an amended timetable from December 21 to 27 to give passengers "greater clarity".
This will include providing "road transport at key locations".
Services have already been affected, with 1.25% of GWR trains cancelled on Wednesday 16 December.
The operator said in a statement it expects to "cancel and change a small number of services during the festive travel window".
It was already predicting trains would be "close to capacity" due to the five-day Christmas bubble window and social distancing guidelines.
GWR managing director Matthew Golton said: "Due to the impact of Covid at some of our locations in the South West, we have taken these steps now to help make sure everyone who has already bought a ticket will still be able to travel, as we take stock of our ability to accommodate additional customers.
"We're sorry for any inconvenience this will bring to anyone travelling over this period who has not currently booked a ticket, but we are doing all we can to ensure that we provide a robust service for those that are already booked to travel with us."