The Department for Transport has effectively taken the nation's rail network into public control to ensure trains continue to run during the coronavirus crisis.
All rail franchise rules have been suspended for at least six months, with the government taking on responsibility for train costs and revenue.
Commuters will also be able to reclaim the cost of pre-paid tickets so long as they agree to stay at home.
All rail workers will also maintain their current terms and conditions under the emergency arrangements.
The dramatic move comes after train operating companies reported a dramatic fall in revenue as the number of people using the railways slumped.
From today, trains will run an emergency timetable to allow key workers to travel to and from their jobs.
Transport secretary Grant Shapps said: "We are taking this action to protect the key workers who depend on our railways to carry on their vital roles, the hardworking commuters who have radically altered their lives to combat the spread of coronavirus, and the frontline rail staff who are keeping the country moving.
"People deserve certainty that the services they need will run or that their job is not at risk in these unprecedented times. We are also helping passengers get refunds on advance tickets to ensure no-one is unfairly out of pocket for doing the right thing.
"These offers will give operators the confidence and certainty so they can play their part in the national interest."
Under the plans set out by the DfT, the current operators will keep running the trains, but on instruction from the department, for a set fee, set as a maximum of 2% of the cost base of the franchise before the Covid-19 pandemic began. This means the feeds will be “far less” than recent profits earned by train operators, Shapps said.
If an operator does not wish to accept an Emergency Measures Agreement, the government’s operator of last resort, which already runs two routes, stands ready to step in.
Shapps said the changes do not amount to a new model for the rail system, but is a temporary solution “to protect services now in a cost-efficient way, and ensuring current events have as little impact as possible on the railway in the longer term”.
A full review of the future of rail franchising hgas been undertaken by former British Airways chief executive Keith Williams and had been expected to be published imminently.
Shapps added that allowing operators to enter insolvency would cause significantly more disruption to passengers and higher costs to the taxpayer.
Paul Plummer, chief executive of the Rail Delivery Group, which represents train operators and Network Rail, said: "The rail industry is working together so that people and goods can keep making essential journeys during this unprecedented national challenge, getting key workers to hospitals, food to shops and fuel to power stations.
"The industry strongly welcomes the Department for Transport’s offer of temporary support and while we need to finalise the details, this will ensure that train companies can focus all their efforts on delivering a vital service at a time of national need."
Shadow transport secretary Andy McDonald said: "Labour backs measures that will keep key workers and freight moving on our railway during this crisis.
"There are very few emergency options available in these most difficult of circumstances. The imperative is to maintain a functioning rail network throughout this emergency.
“However, this is a time-limited arrangement by government in response to a crippling crisis on our railway rather than a long-term solution.
"Labour welcomes an honest debate on the future of our transport system post-crisis in order to address the fundamental issues with our current networks.”
Manuel Cortes, general secretary of the TSSA railworkers' union, said: "We welcome this move, but it’s sad that it has taken a pandemic for the Government to take control of our railways.
“I am immensely proud of the efforts of our members and all across the transport industry in keeping our network open for key workers and for moving freight around the country.”