Train services are ramping up from today as schools reopen in England and Wales, and workers are being encouraged to return to offices.
Timetables are increasing to around 90% of pre-lockdown levels – meaning additional trains and longer carriages on many routes – according to industry body the Rail Delivery Group.
Industry chiefs believe the increased capacity will help people to social distance while travelling.
Anthony Smith, chief executive of passenger watchdog Transport Focus, said: “The rail industry must focus on maintaining good performance so that passengers can travel with confidence.
“Disruption and any crowding from this will be especially unwelcome and has the potential to damage trust in the railway.”
However a recent survey by Transport Focus suggested the majority (77%) of train passengers were satisfied with the ability to keep a safe distance from others.
When it came to how easy it was to find out how busy a train service would be before travelling, this fell to exactly half of passengers.
Some 69% said they were satisfied with the number of people wearing face coverings, which is now mandatory on public transport.
Southeastern is adding an extra 900 carriages and 50,000 seats to its weekday services from today, restoring timetables to 98% of normal levels.
LNER is adding 10 extra Anglo-Scottish services to its timetables, serving destinations including Peterborough, Doncaster, York and Newcastle.
Rail services had been slashed as the UK went into lockdown, although increased to around 80% of normal levels following uplifts in May and July.
The latest government figures show rail usage is at 31% of pre-pandemic levels, while data compiled for Sky News revealed worker footfall in cities was only 17% of normal levels in the first two weeks of August.
But more people are travelling to work than they were two months ago, with 57% of adults surveyed by the Office for National Statistics saying they had travelled to work in the past seven days.
It has followed a push from the government for more people to return to work.
Grant Shapps says he thinks common sense will prevail between employers and employees
Transport Secretary Grant Shapps said last week that it is “now safe to go back” to work.
The risk of contracting COVID-19 on an average journey is below 0.01%, according to a recent study by the Rail Safety and Standards Board.