It means North Wales will have no Avanti services on strike days.
Avanti strongly advised its customers to travel either side of the strikes, saying that a 'significantly reduced' timetable will be in place on the two strike days. Fewer services will run during limited operating hours and trains which will run are expected to be busy.
On Tuesday, Avanti said it will run one train an hour between London Euston and each of Birmingham, Manchester, and Preston, with a limited service to Glasgow. One train every other hour between Liverpool and Crewe will also run.
On Thursday, January 2, the intercity operator will run one train an hour between Euston and each of Wolverhampton (via Birmingham), Crewe and Manchester.
There will also be a limited service between Glasgow and Preston.
These trains will operate during limited hours on both dates - with the first train of the day leaving Euston around 8am and the last train of the day from Euston departing before 5pm.
The greatly reduced timetables will mean North Wales, Blackpool and Edinburgh have no Avanti West Coast services on strike days.
On December 31, there will be no Avanti West Coast trains to or from Macclesfield. On January 2, there will be no Avanti West Coast service to or from Warrington Bank Quay or Wigan North Western.
Avanti said passengers who do travel should plan ahead, expect disruption, and check the details of their last train home.
Kathryn O'Brien, executive director of customer experience at Avanti West Coast, said: "We're disappointed b...