Rail operators are ramping up services from today (Monday) to reflect coronavirus travel restrictions being eased.
But they have warned of a significant reduction in capacity on board to cope with social distancing guidelines.
Across Greater Manchester, Northern has introduced amended timetables from today for key workers and travellers making essential journeys.
They said: "The new timetables will see the introduction of additional services on some routes, but overall capacity on trains will be significantly reduced to assist with social distancing.
"Government advice remains that people should avoid using public transport where possible and Northern continues to ask that only key workers and those whose journeys are essential use rail services."
All passengers are encouraged to wear a face covering.
Northern added: "Those who do need to travel by train should follow a few simple steps. Maintain social distancing where possible, wash hands before and after travel and, if possible, wear a face covering.
"Northern will also continue to support social distancing and enhanced cleaning of touch points at stations and on trains.
"Due to social distancing, there will be significantly reduced capacity on each and every one of our trains.
"We're therefore calling on people to help us keep the railway clear for those who need it most and to only take the train if there’s no other way to travel."
TransPennine Express, meanwhile, said there would be around 15 to 20 seats per carriage.
The operator said: "From Monday, we will be increasing the number of services run in the amended timetable. This has been done in line with the Government's request to increase services to enable those making essential journeys get to where they need to be.
"The advice from HM Government is still for the nation to reduce non essential travel, avoid using public transport and to work from home where possible.
"While there is an uplift in services, there will be significant restrictions on capacity to help enable social distancing, with only around 15 to 20 seats per carriage available for customers."
Industry body the Rail Delivery Group meanwhile said services will be increased from around 50 per cent of the standard timetable, to around 70 per cent.
But in a bid to enable social distancing, their capacity will be reduced to as little as 10 per cent of normal levels.
British Transport Police are expected to have more officers at stations.
All operators are being urged by the Government to rearrange, remove or limit seating 'to try and ensure social distancing is observed'.
People travelling as a household will be allowed to sit together but must maintain 'a safe distance' from other passengers.
Avanti West Coast, which runs trains from Manchester Piccadilly to London Euston, warned passengers that anyone without a reservation may not be able to travel on their choice of train due to capacities being limited to around a quarter of normal levels.
Rail services have been slashed for weeks due to the coronavirus pandemic causing a collapse in demand and a rise in staff sickness.
But the Government is now urging people in England to go to work if they cannot work from home.
Advice in Northern Ireland, Scotland and Wales remains that people should stay at home.
Meanwhile the Rail, Maritime and Transport union described the increase in train services as a 'high-risk strategy' and expressed concern that 'rushed political considerations could well override the safety issues for staff and passengers'.
It has called for new compulsory protections for passengers and rail workers, including the enforcement of two-metre social distancing on trains and the compulsory wearing of face masks by passengers, which should be provided for free at stations and be able to be disposed of safely.
RMT general secretary Mick Cash said: "We are opposed to the early relaxation of lockdown measures and believe that non-essential workers should avoid using trains. When people absolutely must use a train, there should be new compulsory protections.
"We have the crazy situation of Eurostar passengers arriving with masks on into St Pancras but then not wearing masks when they transfer to the tube or other rail services."
A Department for Transport spokesman said the message remained that people should only go to work if they cannot work from home and they should avoid public transport if possible and maintain social distancing if they have no other choice.
He added: "We have asked operators to increase the number of services from today to help reduce pressure on the transport network, providing more space for social distancing as well as delivering increased reliability and extra capacity for the future."
Network Rail chief executive Sir Peter Hendy told BBC Breakfast meanwhile that face coverings were not mandatory for passengers but 'we are all very keen in the rail industry' for people to wear them.
On how a two-metre social distance will be enforced on the railway, he said: "Passengers are sensible.
"This is a national crisis of unprecedented proportions.
"We are relying on people to be sensible. We are doing our best too.
"We want people to stay apart if they humanly can and if they can't, then a face covering is a quite sensible thing to do for the brief moments when you might be getting on or off a train or moving through a station."
