Thousands of London Underground workers and train drivers at rail networks are set to strike in September and October.
RMT (Rail, Maritime and Transport union) and ASLEF (The Associated Society of Locomotive Engineers and Firemen) members are striking in an ongoing dispute over pay and conditions.
ASLEF represents drivers, whereas RMT represents members from lots of different sectors within the rail industry - including station staff and guards.
When ASLEF members go on strike, it usually means there are no drivers. When RMT members go on strike, there is widespread disruption to the network with lots of people in different roles going on strike.
Here is everything you need to know:
RMT members working on the London Underground will strike in September and October.
This involves thousands of Tube staff and means underground services in the capital will be completely shut down on these dates:
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Wednesday 4 October
Friday 6 October
ASLEF train drivers at rail networks across the country are set to strike on these dates:
Saturday 30 September
Wednesday 4 October
There will also be an ASLEF overtime ban - an action short of a strike - on the following days across the UK rail network:
Friday 29 September
Monday 2 October
Tuesday 3 October
Wednesday 4 October - when there is already a strike in place
Thursday 5 October
Friday 6 October
A number of rail services will be affected on these days, albeit not as dramatically as on all-out strike dates.
Avanti West Coast
Avanti West Coast will not be operating any services on Saturday 30 September or Wednesday 4 October.
Customers who booked tickets to travel on these days can claim a full, fee-free refund from their point of purchase.
Customers with pre-booked tickets for travel on a strike day can use their ticket the day before or the two days after.
Avanti West Coast plans to operate its normal timetable during the overtime ban dates.
There will be no C2C service on Saturday 30 September and Wednesday 4 October.
On days when overtime bans are in place, there will be a reduced peak time service and a reduced frequency of two trains per hour during off-peak hours across all routes.
First and last trains will be unaffected.
There will be no Chiltern Railways services on Saturday 30 September or Wednesday 4 October on any routes.
There will also be a "slightly reduced" service on Friday 29 September in preparation for the planned strike day.
Chiltern Railways will be running an amended timetable during the week of overtime bans, which travellers can check here.
There will be no CrossCountry services on Saturday 30 September and Wednesday 4 October.
Some services will be amended during overtime ban dates. You can view the list of trains affected on each day here.
East Midlands Railway
There will be no East Midlands Railway service on Saturday 30 September and Wednesday 4 October.
The train line says it is currently reviewing how the overtime ban will affect its services. Check here for updates.
It says there will be no Thameslink, Great Northern or Gatwick Express services operating on Saturday 30 September and Wednesday 4 October.
A limited Southern shuttle service will run, calling at Gatwick Airport and London Victoria only.
Services the next day after each strike - Sunday 1 October and Thursday 5 October - will begin much later than normal, with some routes having no services before 7am.
On days when an overtime ban is in place, GTR says an amended timetable with fewer services will run.
The usual non-stop Gatwick Express service between London Victoria, Gatwick Airport and Brighton will not run.
To help customers, extra stops at Clapham Junction and East Croydon have been added, so these trains will be operating as Southern services.
Gatwick Express tickets will be valid on Southern and Thameslink at no additional cost.
Find out more about each of GTR's lines by clicking on their names at the top of this section.
Great Western Railway
Great Western Railway (GWR) will be operating a reduced and revised timetable Saturday 30 September and Wednesday 4 October.
Many parts of the network will have no service at all. Services that go ahead will start from 7.30am and all journeys must be completed by 6.30pm.
GWR says there is likely to be short-notice alterations or cancellations to its services on days when overtime bans are in place.
You can check GWR's website for updates nearer the time.
Greater Anglia and Stansted Express
Reduced services are expected to run on both strike and overtime ban days.
You can click here to see what plans are in place on all affected dates.
There will be a reduced frequency of services on Saturday 30 September and Wednesday 4 October.
Heathrow has not announced any changes during overtime bans. Click here for more information about its services.
LNER services will run on an "extremely limited timetable" during strike days, with minor alterations on days before and after them.
You can find more details here.
London Northwestern Railway
There will be no London Northwestern Railway (LNR) service on Saturday 30 September and Wednesday 4 October.
It will have buses in place of trains between Watford Junction and St Albans Abbey on days when there are overtime bans.
You'll be able to see what impact the overtime ban will have on LNR from 27 September here.
There will be no Northern service in operation on Saturday 30 September and Wednesday 4 October, and no rail replacement bus services.
Days affected by overtime bans are likely to cause some short-notice alterations or cancellations. You can check here for updates.
An extremely limited service will operate on a small number of lines during strike days, and most of the Southwestern Railway mainland network will be closed. There will be no service on the Island Line.
Customers are advised to only travel if absolutely necessary.
Reduced services will operate across the mainland South Western Railway network on overtime ban days, with an hourly service on the Island Line.
Find out more here.
There will be no Southeastern service in operation on any routes on strike days.
Southeastern expects to run a full service during overtime ban periods.
No TransPennine Express service will run on any route during the strikes on Saturday 30 September and Wednesday 4 October.
There will also be some early morning and late evening alterations on the days before or after a strike day.
The TransPennine Express website will be updated on 27 September regarding the impact of overtime bans.
West Midlands Railway
There will be no West Midlands Railway service on Saturday 30 September and Wednesday 4 October.
On days when the overtime ban is in place, reduced train services will operate between Birmingham New Street and Hereford and Birmingham New Street and Shrewsbury - and a bus service will replace trains between Nuneaton and Leamington Spa via Coventry.
You'll be able to see what impact the overtime ban will have on West Midlands services from September 27 here.
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You can click on any of the links provided above to check for updates on specific lines.
National Rail urges anyone hoping to travel on strike and overtime ban days to use its Journey Planner to keep an eye on how services will be affected.
It says most travel information up to 30 September is showing correctly, but any journey accompanied by a yellow warning triangle means the information is still subject to change.
The amended timetables for subsequent dates are expected to be showing correctly in Journey Planners at the following times:
For journeys from 2 to 6 October, there will be an amended timetable on Wednesday 27 September.
If you are planning to travel on Gatwick Express, Great Northern, Southern or Thameslink, journeys on 5 and 6 October will be updated on Friday 29 September.