The head of Network Rail has claimed the service will not be ready to handle the amount of passengers it dealt with before the coronavirus crisis.
Sir Peter Hendy claimed more passengers would probably have to travel off-peak, and that long-distance services could become reservation-only.
Speaking on the Today programme, he claimed social distancing “may limit the capacity” of trains when the lockdown is lifted.
He explained: “On long-distance trains and coaches we have got reservation systems so we can allocate seats.
“In urban areas it may well be that we can’t carry the numbers who would normally travel.”
There are no finalised plans for when or how trains will return to full service.
His comments come after Transport Secretary Grant Shapps claimed more people would work at home permanently when the crisis ends.
ASLEF, the train driver’s trade union admitted a return to full services was unlikely in the immediate future.
General Secretary Mick Whelan said: “We are working with the industry to ensure key workers and medical food and supplies are delivered.
“There have been no discussions on a return to full service but, given the fluctuating staff numbers, logistically, it would be unlikely.
“There would also need to be a very strong case made before we would be assured that it would be 100 per cent safe to do so.”
It comes amid fears over the safe use of public transport.
Despite train use falling by 95 per cent, some tubes have been still overcrowded in a clear breach of social distancing measures.
Passengers have already been told to board buses by the middle doors to avoid contact with the driver after the death of 21 transport workers in the capital.
Five hundred transport cops are currently patrolling the UK’s rail network to enforce the PM’s coronavirus travel clampdown.
They have been tasked with making sure passengers know ONLY those making essential journeys for work should now be using the Tube and trains.
