Thousands of railway workers were staging their second strike of the week on Thursday after talks failed to resolve a bitter row over pay, jobs and conditions.
Members of the Rail, Maritime and Transport union (RMT) at Network Rail and 13 train operators will take industrial action, crippling services across the UK.
Only around one in five trains will run and mainly on main lines during the day.
Ahead of the strike, the Government announced plans to change the law to enable businesses to supply skilled agency workers to plug staffing gaps during industrial action.
Ministers pointed out that under current trade union laws, employment businesses are restricted from supplying temporary agency workers to cover for strikers, saying it can have a “disproportionate impact”.
The legislation will repeal the “burdensome” legal restrictions, giving businesses impacted by strike action the freedom to tap into the services of employment businesses who can provide skilled, temporary agency staff at short notice, said the government.
Network Rail welcomed the move but Labour and unions condemned it as a “recipe for disaster.”
The RMT accused Transport Secretary Grant Shapps of “wrecking” negotiations.
RMT general secretary Mick Lynch said: “Grant Shapps has wrecked these negotiations by not allowing Network Rail to withdraw their letter threatening redundancy for 2,900 of our members.
“Until the Government unshackle Network Rail and the train operating companies, it is not going to be possible for a negotiated settlement to be agreed.
“We will continue with our industrial campaign until we get a negotiated settlement that delivers job security and a pay rise for our members that deals with the escalating cost-of-living crisis.”
Mr Shapps hit back, saying the RMT claim was a “lie”.
Meanwhile, members of the drivers’ union Aslef on Greater Anglia will strike on Thursday in a separate dispute over pay.
The company, which is also affected by the RMT strike, advised passengers to travel only if it was necessary.
The Transport Salaried Staffs’ Association (TSSA) announced that its members at Merseyrail had accepted a 7.1% pay offer.
General secretary Manuel Cortes said: “What this clearly shows is our union, and sister unions, are in no way a block on finding the solutions needed to avoid a summer of discontent on the railways.
“Rather, it is the Government who are intent on digging in their heels. Grant Shapps would be wise to start talking seriously to our union as we ballot for industrial action on our railways up and down the land.”
A Rail Delivery Group spokesperson: “With passenger numbers still at only 80% of pre-pandemic levels the industry remains committed to giving a fair deal on pay while taking no more than its fair share from taxpayers.
“We can only achieve that by making improvements – like offering better services on a Sunday – that reflect the changing needs of passengers so we can attract more back.
“We call on the RMT leadership to continue to talk so that we can secure a thriving long-term future for the railway and its workforce.
“Our advice to passengers remains the same, only travel by rail if absolutely necessary, check before you travel and make sure you know the time of your first and last trains.”
A Network Rail spokesperson said: “We are disappointed that the RMT have again chosen to walk away from negotiations without agreeing a deal. We remain available for talks – day or night – and will do everything we can to avoid further disruption for our passengers.
“As a result of this needless and premature strike, rail services will look much like they did on Tuesday – starting later in the morning and finishing much earlier in the evening (around 6.30pm).
“We are asking passengers to please check before you travel, be conscious of when your last available train is departing, and only travel by train if necessary.”