Physical distancing on trains and at stations in Scotland will reduce to a minimum of one metre from Monday (July 27).
ScotRail and Network Rail are introducing the measure, after the Scottish Government updated its guidance earlier this month.
It stated that the rule could be relaxed to 1m in certain environments - such as hospitality or public transport - where safety measures have been put in place.
ScotRail says it believes it has put enough safety measures in place to merit the move.
This includes the provision of hand sanitiser and face masks at the busiest stations - with face masks already compulsory on services and in concourses for most people.
It says it has also introduced platform markings and guidance at ticket vending machines, along with announcements and messages on information screens.
The operator says the capacity of trains remains significantly reduced to support physical distancing, and it is urging people to follow five rules for travel - including taking their journeys outwith peak times, and avoiding boarding a train if it looks unsafe.
Passengers are also being encouraged to buy tickets in advance of travel.
David Simpson, ScotRail's operations director, said: "We’ve worked closely with staff, trade union colleagues, and the government to satisfy ourselves that we have sufficient safety measures in place to move to a minimum of one metre physical distancing on trains and at stations.
"The provision of face masks and hand sanitisers at our busiest stations are just some of the measures we introduced in recent weeks to keep staff and customers safe.
"But we need everybody to continue taking personal responsibility for their travel choices, because physical distancing can’t be guaranteed. Customers who do travel with ScotRail should follow our five rules for safer travel, including the wearing of a face covering on trains and at stations."