Hundreds of trains serving London and south-west England will return to service as lockdown continues to ease.
South Western Railway (SWR) said 244 services would be added to weekday timetables, ahead of more restrictions being lifted on Monday 17 May.
SWR said the move would support regional tourism and the hospitality industry as businesses reopened.
However, it warned social distancing might not always be possible and urged passengers to avoid peak times.
The new timetable, which comes into effect on Sunday 16 May, means 85% of weekday trains will have resumed service compared with pre-pandemic levels.
Saturday services will be up to 92% and Sundays at 99%, the operator said.
Managing director Claire Mann said: "As more customers enjoy the freedom of travelling again, it is inevitable that there will be times when trains will be busy.
"To support social distancing, we ask customers to help us by planning ahead and considering travelling outside peak time - please check our website for information on our busiest services."