Passengers in England, Scotland and Wales face severe disruption after last-ditch talks failed to stop the biggest rail strikes in 30 years.
Thousands of staff at Network Rail and 13 rail operators are due to walk out on Tuesday, affecting most major lines.
Mick Lynch, general secretary of the RMT rail union, blamed the "dead hand" of government, saying ministers did not allow employers to negotiate freely.
The transport secretary said "outdated unions" were "opposing progress".
Grant Shapps said about 20% of services were expected to run during the strikes on Tuesday, Thursday and Saturday, focusing on key workers, main population centres and critical freight routes.
Services are expected to be affected from Monday evening, with disruption continuing on non-strike days this week.
The RMT, which represents rail workers ranging from catering staff to signallers, is calling for a pay rise of at least 7%.
The union said employers have only offered 2%, with the possibility of 1% more, on the condition that workers accept proposed job cuts and changes to working practices.
Network Rail chief executive Andrew Haines said "no strike is inevitable until the moment it begins", but urged passengers to travel by train only if necessary. A special train timetable for 20 to 26 June was published on Friday.
A strike will also take place across the London Underground on Tuesday.
Talks were held on Monday afternoon to avert the strikes but the sides remained deadlocked, Mr Lynch said, accusing the government of interfering to prevent a deal.
"What we've come to understand is the dead hand of this Tory government is all over this dispute and the fingerprints of Grant Shapps and the DNA of [chancellor] Rishi Sunak are all over the problems on the railway," he said.
"Until they allow these employers to negotiate freely I can't see we're going to get a resolution."
He said staff were faced with thousands of job cuts, reduced pensions, worse terms and conditions, and a cut in real-terms pay as inflation soars.
Mr Lynch said there was also a plan to close every ticket office in Britain. The Department for Transport said no final decision had been made, but said it was "absurd" to suggest it wanted to close every booking office.
The transport secretary has denied the government intervened in the dispute, saying "no minsters have ever been involved directly in these strike negotiations" and only the employers and union could reach an agreement.
In the House of Commons, Mr Shapps said the government could no longer tolerate rail unions using their right to strike "without any regard for how the rights of others are disrupted".
He said minimum service legislation, which requires train companies to maintain a base level of service even during strikes, was part of the solution.
Is the government involved in talks or not?
The short answer to this is yes.
The transport secretary says he does not want to get involved in a dispute between the RMT on one side and Network Rail and the train operating companies (TOCs) on the other, but the interaction between the two employers means the government has a pivotal role.
According to government officials, Network Rail is in theory able to offer a higher pay settlement than the 3% they are currently offering by shuffling their large and complex overall budget.
However, the government accepts that any pay offer to Network Rail employees would set the bar for a settlement for the train operating companies.
Since the government is now also standing as the financial backstop to the Covid-ravaged train operating companies, that could frustrate its stated ambition of putting the rail industry on a sustainable financial footing given that revenues for the train companies are still languishing just above half their pre-pandemic levels.
The government may not be in the room but it is at the table.
Mr Shapps told MPs rail unions were preventing the industry from updating "obsolete working practices", such as voluntary Sunday working - which he blamed for the cancellation of 170 trains before the Euro 2020 final last year.
He said it was "factually incorrect" to say the strike is about a pay freeze and said reforms for the railways would include a "decent annual pay rise" for staff.
"It's about outdated unions opposing progress, progress that will secure the future of the railway," he said.
Addressing union members directly, he said: "Your union bosses have got you striking under false pretences and, rather than protecting your jobs, they are actually endangering them and the railway's future."
Labour said that if the strikes go ahead, they will represent a "catastrophic failure of leadership" by ministers.
Shadow transport secretary Louise Haigh said of Mr Shapps: "Not only has he been boycotting the talks, he's tied the hands of those at the table."
She said Mr Shapps had not given train operating companies "any mandate to negotiate" and the talks were "a sham, because ministers have set them up to fail".
Network Rail says the last trains between many major cities are expected to depart over the course of Monday afternoon, before more than 40,000 rail workers walk out. The strike begins at 00:01 BST on Tuesday.
Although ScotRail and Transport for Wales are not involved in the dispute, train services will be disrupted as the railways rely on Network Rail staff. ScotRail said 90% of trains will be cancelled during the three days of strike action.
The reduced timetable will be in place until Sunday, with just 20% of usual services running on strike days. Trains that do run will start later and finish much earlier than usual - between 07:30 and 18:30.
South Western Railway said it will run a "severely reduced timetable" on strike days, with significant sections of the network closed and a very limited service between 07:15 and 18:30 BST on some routes for those who have to travel.
Great Western Railway will only operate 30% of its usual timetabled services on strike days and about 50% on non-strike days.
West Midlands Railway, which will run a limited service on a small number of routes, urged customers to travel only if it is essential and if "no other transport option is available".
Knock-on disruption is expected on the roads, with motorists being warned to expected a surge in traffic.
Motoring group the AA says drivers in Scotland and Wales should expect to face long queues as most railway lines will be closed.
The M74, M8 and A9 in Scotland and the M4, A55, A5, and A483 in Wales could see severe traffic, it says.
The RAC says major city routes and those serving the home counties are likely to see some of the biggest increases in traffic volumes.
The strikes will affect a number of events including school exams and the first Glastonbury Festival for three years.
Rail strike advice
Can I get a refund? Yes, if you cannot get your train due to strike action. Season-ticket holders can apply for a refund for the days affected. Find more info here.
Do I have to go to work or school? This is up to your individual employer or school, check with them.
How can I plan my train journey? Use the National Rail journey planner.
Read more here.
Leaders at 13 trade unions and the Trades Union Congress (TUC) have jointly written to Mr Shapps urging him to "help deliver a fair resolution". The Labour Party has also called on the government to step in.
TUC general secretary Frances O'Grady said nobody took strike action lightly but argued low-paid rail staff such as caterers and cleaners had been left with "no other option".
"It's insulting to ask them to take yet another real-terms pay cut when rail companies took £500m in profits during the pandemic," she said.
Rail Delivery Group chair Steve Montgomery said that passenger numbers were at 80% of pre-pandemic levels and the industry wanted to give "a fair deal on pay while taking no more than its fair share from taxpayers".
Meanwhile, under new legislation the government is expected to introduce this week, employers would be able to replace striking workers with agency staff.
The new law, which is likely to come into force from mid-July, has been criticised by the Trades Union Congress and the recruitment industry for undermining the right to strike and creating safety risks.
Additional reporting by Kathryn Snowdon
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