Millions of rail passengers face disruption until the end of 2019, mainly due to strikes about the role of guards.
These are the key questions and answers.
Who is walking out – and when?
Members of the RMT union working for South Western Railway will strike for almost all of December. They will work normally only on 1 and 12 December (the day of the general election); no services were scheduled to operate on Christmas Day or Boxing Day.
South Western Railway (SWR) is the network based at London Waterloo, the UK’s busiest station. Its trains serve southwest London, Surrey, Hampshire, Berkshire, Wiltshire, Dorset, Somerset and Devon.
In addition members of the RMT union working for West Midlands Railway (WMR) are stopping work on every Saturday until the end of December. This will also affect some London Northwestern Railway services.
The two train operators – part of the same organisation – run services in the West Midlands and beyond, extending as far as Shrewsbury to the west, Kidderminster and Worcester to the southwest, Stratford-upon-Avon to the south and Northampton and London Euston to the southeast.
What will the effect be on South Western Railway?
SWR normally uses “contingency guards” (staff specially trained to work on passenger services) and non-striking guards. But because the strike is so protracted these usual mitigations will not be as effective.
Between Monday and Friday, SWR expect to run more than half of the normal schedule, “prioritising capacity during peak periods” – though it warns: “Peak services will be much busier than normal and we may have to introduce queuing at a number of our busiest stations.”
To concentrate resources over a shorter spell each day, “services will finish earlier than normal at around 11pm”.
The standard pattern on the key lines from Portsmouth via Guildford and Southampton via Woking to London Waterloo will be to run one fast and one slow train each hour. West of Southampton, some trains will run to Bournemouth. A shuttle will run each hour between Bournemouth and Weymouth.
Between Reading and London Waterloo, the usual three-per-hour service will be reduced to half-hourly.
This will cause problems for travellers on 24 and 27 December who would normally use GWR between London Paddington and Reading. All GWR lines will be closed because of track and overhead wiring work. InterCity services to Exeter, Plymouth, Bristol, Cardiff and Swansea will start and end at Reading.
SWR was expected to run extra services between Reading and London Waterloo, but the strike will result in fewer trains than usual.
No SWR trains are likely to run from Weybridge to Virginia Water, Ascot to Aldershot and Epsom to Effingham Junction. Buses will replace trains.
The same may apply on the Exeter line west of Salisbury.
On some other lines – Southampton and Yeovil to Bristol, and Epsom to Dorking – passengers can use their tickets on GWR and Southern respectively.
What will the effect be on West Midlands Railway?
The train operator says it will be able to provide only “a very basic service” on Saturdays, adding: “Virgin Trains, Cross Country, Chiltern Railways and Transport for Wales are due to run a normal Saturday timetable, but will be busier as people make their way to and from the Christmas Markets.”
WMR says: “The busiest time to travel around the West Midlands will be between 3 and 4pm and at the end of the day.
“Don’t aim for the last train home: get there early and be prepared to queue at busier stations.”
On the lines from Northampton via Rugby and Coventry to Birmingham New Street, from Lichfield via Birmingham New Street to Bromsgrove and Redditch, and from Wolverhampton to Walsall via Birmingham New Street, two trains will run each hour.
But key lines will have only a bus replacement service: Walsall-Rugeley, Wolverhampton-Shrewsbury, Kidderminster-Worcester, Shirley-Stratford and Bromsgrove-Worcester.
Any other problems?
Yes. Many Eurostar trains from London to Paris will be cancelled on 5 and 6 December as a result of a nationwide general strike on 5 December 2019.
The train operator says: “The strike action will impact our ability to deliver the usual timetable as we expect disruption to signalling along all routes. As a result, we will now run a reduced timetable on 5 and 6 December.”
What is the root of the UK disputes?
Staffing on trains. Every British train (apart from on the automated Docklands Light Railway) has a driver. Train operators staff their trains in different ways to suit different scenarios. Long distance inter-city services typically have several staff on board, while short distance, high-frequency services often operate with just the driver.
Under driver-only operation (DOO), the train driver is responsible for opening and closing the doors and determining that it is safe to start the train. He or she is the only member of staff on the train.
DOO trains started running in 1982 in the UK, between London St Pancras and Bedford, and have gradually spread to other areas.
Many train operators say they are keen to move to driver-controlled operation (DCO). This is common on many routes. The train driver operates the doors and decides when it is safe to move the train. There are usually other members of staff on the train.
The disputes are largely about whether a DCO train should operate if a guard – a second, safety-critical member of staff – is unavailable.
The Rail Delivery Group (RDG), representing train operators and Network Rail, says that more than half of passenger journeys on Britain’s railway are made on trains where the driver controls the doors.
The RMT union uses a different statistic, saying: “Seventy per cent of the rail services operate safely and efficiently with a guard.
“That means that the standard rail industry operation is with a guard.”
Why did the row flare up?
Modern trains are designed for DCO, and the Department for Transport (DfT) is driving moves to making this standard mode of operation. Guards are being retained. They have a key role to help people of reduced mobility, provide information to passengers and increase the perception of safety and security on board.
But one perceived benefit of DCO is that trains can continue to run if, for some reason, the guard is unavailable – typically during times of disruption.
The DfT was criticised by the National Audit Office in 2018 for failing to “fully evaluate the possible effects on passengers of different scenarios of industrial action before awarding the contract” to Govia Thameslink Railway, parent of Southern.
Some observers say this is a dispute about union power rather than safety. If a train can operate without a guard, then strikes by guards are ineffective. Most drivers are members of the Aslef union; most guards are members of the RMT.
The RMT dismisses this suggestion, saying: “This dispute has been entirely manufactured by the Department for Transport to increase company profits and to confront the unions.
“The passengers are the victims and the unions are fighting to defend them and safety standards.”
How dangerous is driver-controlled operation?
The Rail Safety and Standards Board (RSSB) says: “We have published several research projects over the last 15 years on various aspects of DCO on passenger trains.
"None of these pieces of work has identified any increased risk from dispatching a train without a guard being present - providing the correct procedures have been followed. In fact, the removal of any possible miscommunication, which could exist between driver and guard could, potentially, deliver some safety benefits.
“Train travel continues to be fundamentally safe and that the risks are extremely low, regardless of whether the train operates with a guard, other auxiliary on-board staff or with just the driver.”
Certainly the many strikes have increased risks for passengers, by encouraging travellers to switch to the roads – which are far more dangerous than rail.
When did the strikes start?
At 11am on 26 April 2016, initially on the Southern network – serving south London, Surrey and the Sussex coast from London Victoria and London Bridge stations.
Mick Cash, general secretary of the RMT union, said at the time: “This dispute is about safety and the safety-critical role of the guards on Southern trains.
“The company, with an eye on ever-fatter profits, is prepared to axe the guards on some of the most overcrowded and potentially dangerous services in Britain so that they can squeeze every last penny out of their passengers regardless of the consequences.”
What do the big political parties say?
Labour backs the RMT demands and would end driver-only operation of trains. The shadow transport secretary, Andy McDonald, says: “We have stood side by side in the struggle against DOO and will continue to.
“I’ve been on your picket lines and so has Jeremy Corbyn.”
Earlier this year Jeremy Corbyn told The Independent: “It’s very much Labour policy that there should be fully staffed trains in all parts of the country at all times.”
The Conservatives claim that more than 160 days of strikes have taken place or are planned and that 11 out of the country’s 17 rail franchises have been affected.
The Tories say they would guarantee minimum service levels during rail strikes.
The transport secretary, Grant Shapps, said: “The Conservative Party will introduce a new law to ensure that the railways keep on running even if trade unions vote to go on strike.” Commuters may wonder why this policy has only just been announced.