Rail operator Greater Anglia will run a reduced timetable in response to the coronavirus pandemic.
The East Anglian-transport provider said it would be running a service "similar to a Sunday" from Monday, with additional trains at the beginning and end of the working day.
Most routes will see an hourly service, with three trains an hour going from Colchester and Chelmsford to London.
Greater Anglia said it had also stepped up cleaning of its trains.
Services between Southend to London and Hertford to Stratford will run half-hourly, while trains between Ipswich and Peterborough will run every two hours.
Jamie Burles, Greater Anglia managing director, said: "This reduced timetable reflects the mix of factors affecting train travel in these challenging times. We need to continue to provide a reliable service for those who are working and still need to travel.
"At the same time, we need to run a timetable where the service can still be provided consistently, as some of our staff may need to self-isolate. It also reflects the significant reduction in the numbers of passengers travelling."
He added that the timetable would be kept under review while thanking staff for their work during the outbreak.
Greater Anglia said it had increased cleaning on trains and in stations, especially on grab rails, door buttons, handles and ticket gates, and it had topped up soap, water and toilet roll more frequently in toilets.