Passengers using West Midlands and London Northwestern Railway services face disruption between 29 January and 6 February due to ASLEF industrial action.
The leaders of the RMT and ASLEF have sent a joint letter to the Mayor of London asking for the Elizabeth Line and London Overground into public ownership.
The ASLEF Union will be holding industrial action this May and passengers are being asked to check their travel plans with changes to services expected.