Drivers at 16 rail companies have started a fresh wave of strikes, plus overtime bans, causing disruption to the rail network.
The strikes are part of a long-running dispute over pay and will take place across April and May.
Overtime bans, an action short of a strike, also mean some services may not be running or may be reduced as drivers refuse to work their rest days.
Tube strikes planned for April and May have been called off.
In an "entirely separate dispute", ASLEF members will also strike and refuse to do overtime at LNER on specific dates in April "because of the company's failure to adhere to the agreed bargaining machinery", the union said.
LNER's alleged failure to adhere to bargaining machinery refers to it using managers to drive trains on strike days.
People are advised to check before they travel.
Here's what's happening when:
The rail strike dates
Friday 5 April
Strikes will affect Avanti West Coast, East Midlands Railway, West Midlands Trains, and CrossCountry.
Saturday 6 April
Strikes will affect Chiltern, GWR, LNER, Northern, and TransPennine Trains.
Monday 8 April
Strikes will affect Greater Anglia, c2c, GTR Great Northern Thameslink, Southeastern, Southern/Gatwick Express, South Western Railway main line and depot drivers, and SWR Island Line.
Overtime ban dates:
Thursday 4 April
Friday 5 April
Saturday 6 April
Monday 8 April
Tuesday 9 April
People are advised to check before they travel, as some areas may have no service.
LNER action dates:
Members will strike on Saturday 20 April and refuse to work non-contractual overtime from Friday 19 to Sunday 21 April.
Why are the strikes happening?
ASLEF says the LNER strikes are because of "the company's persistent failure to comply with existing agreements".
Nigel Roebuck, an ASLEF organiser in the northeast, said the operator had been trying to get "every driver manager and driver instructor to work on strike days".
A spokesperson said: "LNER has used managers - paid £500 a shift - to drive trains on strike days and, after the expiry of the last non-contractual overtime agreement, on most days of the week now.
"There is no agreement in place for management to drive services on mainline infrastructure.
"It results in branch line services - such as Lincoln, Skipton, and Harrogate - being cancelled because of a lack of route knowledge and means virtually no driver training is being done."
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Tap hereMick Whelan, ASLEF general secretary, said of the rail strikes: "Last month, when we announced renewed mandates for industrial action, because under the Tories' draconian anti-union laws we have to ballot our members every six months, we called on the train companies, and the government, to come to the table for meaningful talks to negotiate a new pay deal for train drivers who have not had an increase in salary since 2019.
"Our members voted overwhelmingly - yet again - for strike action."
A Rail Delivery Group spokesperson said: "Nobody wins when industrial action impacts people's lives and livelihoods, and we will work hard to minimise any disruption to our passengers.
"We want to resolve this dispute, but the ASLEF leadership need to recognise that hard-pressed taxpayers are continuing to contribute an extra £54m a week just to keep services running post-COVID.
"We continue to seek an agreement with the ASLEF leadership and remain open to talks to find a solution to this dispute."
When the strikes on the London Underground were announced, Finn Brennan, ASLEF's full-time organiser on the network, said in a statement: "ASLEF Tube train drivers will strike in April and May in a long-running dispute over London Underground's failure to give assurances that changes to our members' terms and conditions will not be imposed without agreement and that all existing agreements will be honoured.
"Despite a previous commitment to withdraw plans for massive changes to drivers' working conditions, London Underground management has established a full-time team of managers preparing to impose their plans.
Sadiq Khan said they had been called off after "talking and engaging with transport staff and trade unions rather than working against them".
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