Nine train companies are due to be hit by walk-outs on Saturday, bringing a large part of the rail network to a standstill, including Chiltern Railways, Gatwick Express and West Midlands Railway.
Millions of customers will be affected on what could be the last scorching hot Saturday of the summer.
Although the walkout directly affects nine companies only, others have warned that the knock-on effect could cause significant disruption.
Mick Whelan, general secretary of Aslef, has said strikes are "always the last resort".
He added: "We don’t want to inconvenience passengers – our friends and families use public transport, too – and we don’t want to lose money by going on strike but we’ve been forced into this position by the companies, who say they have been driven to this by the Tory government.
"Many of our members – who were the men and women who moved key workers and goods around the country during the pandemic – have not had a pay rise since 2019."
A breakdown of the impact across the rail operators is as follows.
Avanti West Coast
All services across Avanti West Coast routes have been cancelled.
The company is "strongly" advising customers to avoid travelling unless they have to, given a knock-on effect from other operators.
Busy trains, short-notice cancellations and delays are all thought to be likely.
A reduced service of one train per hour is running on the Aylesbury Vale Parkway - Marylebone route between noon and 8pm.
CrossCountry will not run any services on Saturday.
Although its drivers are not striking, services are likely to be "impacted" given industrial action on London Overground and Southeastern.
Great Western Railway
A limited service will operate between Bristol Temple Meads - London Paddington, Reading - Oxford and Reading - Basingstoke.
Timetables will start later and finish earlier than normal.
Greater Anglia has asked customers to avoid travelling with their "heavily reduced and disrupted" service.
One train per hour will run in each direction between London - Norwich, London - Colchester, Southend Victoria - Liverpool Street, and Liverpool Street - Stansted Airport.
All Heathrow Express services have been cancelled.
A "significantly reduced" timetable is running, consisting of one service to and from King's Cross.
London North Eastern Railway
No trains are running north from Edinburgh Waverley, while southbound trains are restricted to one every two hours.
No trains are running north from Leeds, while just one train is running south to London King's Cross.
One northbound train per hour is running from King's Cross, while one northbound and one southbound train is running every two hours from Newcastle.
London Northwestern Railway
No London Northwestern Railway services are running.
Although services are running as normal, strikes affecting other operators could make trains busier than normal.
All Southeastern services have been cancelled.
Southern drivers are not involved in Aslef's strike, but services may be "impacted" given disruption on London Overground and Southeastern.
Stansted Express have advised customers to avoid travelling on Saturday.
One train each way is running between Stansted Airport and London Liverpool Street every hour.
Engineering work means there will be a bus during the journey between Waltham Cross and Harlow Town.
Transport for Wales
Although not directly affected by strikes, services are likely to be hit by the reduced timetable of other operators.
Customers have been advised to avoid non-essential travel between Carmarthen - Newport, Cardiff - Lydney, Shrewsbury - Wolverhampton, and North Wales Coast, since trains are expected to be busy.
West Midlands Railway
No West Midlands Railway services are running on Saturday.
For a full rundown of all of the train services operating tomorrow, make sure to check your company's website.