People are facing 27 days of rail chaos throughout December as South Western Railway (SWR) workers go on strike.
The action is part of a long-running dispute over the role of guards on trains.
Members of the Rail, Maritime and Transport union will walk out between December 2 and New Year's Day, with mass disruption expected over the Christmas period.
South Western Railway has confirmed a "reduced service" will run across the network Monday 2 December until Friday 20 December.
This includes no SWR service between Bristol Temple Meads and Bath Spa.
The company is warning some routes will have no train service or replacement bus service. Departures are expected to finish earlier than usual too, at around 11pm.
Peak services are expected to be "much busier" according to SWR. The provider has said it "may have to introduce queueing" at busier stations.
An amended timetable is in place on Thursday 12 December.
South Western Railway tweeted there is insufficient time "to reinstate a full service" between strike days.
RMT General Secretary Mick Cash said their members have been left with "no choice" but to strike.
Our members have been left with no choice but to call a further 27 days of strike action on South Western Railway.
RMT members will not book on for duty from:
00:01 on Monday December 2 until 23:59 on Wednesday December 11
00:01 on Friday December 13 until 23:59 on Tuesday December 24
from 00:01 on Friday December 27 until 23:59 on January 1
South Western Railway has promised to keep guards on trains and says it will do everything possible to keep customers moving during the strikes.
We have done everything we can and more to meet the RMT’s outdated demands with our promise of a guard on every train, and a safety critical role for that guard. What we are not prepared to compromise on is the much needed modernisation of the service with improved performance, safety and customer service that our new fleet of modern suburban trains will vitally deliver for customers. We know our passengers will welcome over 10 million more passenger journeys a year arriving on time and this much needed improvement to our service is too important to compromise.