When are the strikes?

The strikes start at 0.01am on Monday and in effect run for the rest of the month. RMT union members will strike for 27 days – all the rest of December except Christmas Day and Boxing Day, when no trains run anyway, and 12 December, general election day, a hiatus too short to bring back full services.

How much disruption will they cause?

South Western Railway (SWR) expects to run about half of its trains most weekdays, with no trains after 11pm. Peak services are likely to be extremely busy where frequencies are cut, with queueing systems in place at busy stations. For commuters already used to standing on overcrowded trains, it could be a grim month even if their trains are running.

Why are they taking place?

The strikes are part of an ongoing row about the role and responsibilities of guards. New trains allow driver-only or driver-controlled operation – including closing the doors – and unions want to ensure guards keep a safety-critical role. Although SWR says it will guarantee a second crew member onboard, unions say they have not had sufficient assurances and believe that guards could be axed in the future if companies choose to do so.

Is there a chance of an agreement?

Two days of talks at Acas last week ended acrimoniously with each side publicly accusing the other of having no interest in calling off the strikes. Even a sudden reconciliation is unlikely to avert immediate disruption now contingency plans have been triggered. Both sides say they remain available for talks.

Are similar disputes taking place on other rail routes?

Yes – officially at Southern, Northern, Merseyrail and West Midlands. West Midlands is holding strikes every Saturday until the start of 2020.