People wanting to use trains are being reminded to only use them if their trips are necessary, in a bid to limit passenger numbers.
Great Western Railway has issued a warning to members of the public, telling them not to use trains for leisure or exercise purposes.
This is so people who "have no alternative" mode of transport can use them safely and adhere to social distancing guidelines.
It comes as Boris Johnson announced the latest steps to easing the coronavirus lockdown next week.
In a statement GWR's Interim Managing Director Matthew Golton asked members of the public "to avoid the train if they can, including not using services for leisure purposes or as part of daily exercise."
With social distancing guidance in place we are able to carry as little as a tenth of the usual number of passengers, and customers are not yet able to use trains as freely as they once did. We are doing everything we can to carry as many people, safely, as we can. This will make sure that those who absolutely need to travel by train can do so. But I must ask you, is your journey really necessary?
The rail service has acknowledged that maintaining social distancing can be challenging on public transport, so has urged passengers who need to use trains to take the following measures:
Wear a face covering
Plan ahead - book tickets online in advance where possible and avoid peak travel times
Wash hands prior to travelling and after every journey
Use the hand sanitiser located at all main stations
GWR has restricted the number of reservations available on its services and has added floor stickers on trains and at stations to help customers maintain a two metre distance from one another.
It is currently operating about 70% of its usual services and is taking a "staged approach" to returning to its full timetable due to staff sickness.