Members at 16 train operating companies will refuse to work overtime until Saturday, December 9, having kicked off their industrial action on Saturday, December 2.
Train companies said they would operate as many trains as possible but there would be wide regional variations, with some operators running no services at all on strike days.
Services that are running will start later and finish much earlier than usual – typically running between 7.30am and 6.30pm.
Drivers on East Midlands Trains and LNER went on strike on Saturday, crippling services on a busy pre-Christmas shopping day.
Aslef members on Avanti West Coast, Chiltern Railways, West Midlands Trains and Great Northern/Thameslink held a strike on Sunday, with an expected knock-on impact on services on Monday morning.
The union announced the action on November 16 in an effort to “ratchet up the pressure” on the government.
When are the next train strikes?
As part of the strike, drivers will also decline to put in any overtime from December 1 to 9.
Which train companies will be affected?
East Midlands Railway and LNER on Saturday, December 2
Avanti West Coast, Chiltern, Great Northern Thameslink, and West Midlands Trains on Sunday, December 3
C2C and Greater Anglia on Tuesday, December 5
Southeastern, Southern/Gatwick Express, SWR main line, SWR depot drivers, and Island Line on Wednesday, December 6
CrossCountry and GWR on Thursday, December 7
Northern and TPT on Friday, December 8
Why are train drivers striking?
In the 18-month-long dispute, which began when union leaders turned down a salary offer in the spring, little progress has been made.
Aslef's general secretary Mick Whelan said: "Our members have spoken and we know what they think. Every time they vote – and they have voted overwhelmingly for strike action in pursuit of a proper pay rise – it is a clear rejection of the offer that was made in April."
The compensation offer from the Rail Delivery Group, which represents rail operators, was deemed "risible" by Mr Whelan.
A number of adjustments to working procedures and a compensation agreement that included a four per cent pay increase retroactively for 2022 and an additional four per cent increase for 2023 were included in the offer made in April.
In 2021, the annual median salary for train drivers was £59,189.