West Midlands Railway has been struggling with a driver shortage for months and is urging passengers to check their journeys carefully this month ahead of a new timetable being introduced ahead of the festive season.
Departure times on some of the company's routes will change from Sunday, December 12.
With trains expected to be busy in the run-up to Christmas, passengers are advised to check their travel plans.
The operator is also reminding passengers that some services may be cancelled at short notice due to ongoing staffing shortages caused by the impact of the pandemic on its driver training programmes along with a recent increase in Covid-19 related absences.
Jonny Wiseman, WMR customer experience director, said: "Over recent months, we have been delighted to welcome more passengers back to the railway following the easing of coronavirus restrictions.
"With timetables changing next week and the impact of Covid-19 creating the possibility of cancellations due to driver shortages, I am urging passengers to check their journeys before setting out to the station and to avoid relying on the last train home wherever possible.
"We do all we can to avoid cancellations but where we have no choice we always look to give passengers as much notice as possible and arrange alternative transport wherever possible.
"I would like to thank our passengers for their understanding as we continue to work our way through our driver training backlog."
Passengers are also being reminded it is once again mandatory to wear a face covering when on board public transport and fines for non-compliance may apply.