Train and tube strikes are set to hit travellers over the Christmas period.
London Underground will stage a strike on Boxing Day, while London Midland drivers will walk out on December 23 for 24 hours.
Arriva Trains Wales is also planning industrial action, but a date has not been set yet.
Train drivers’ union Aslef wants to make a deal with London Midland, formed by the merger of Silverlink and Central Trains three years ago.
“Some drivers are being paid £1200 less than others for doing exactly the same job,” said official Mick Whelan.
The London Midland strike is expected to hit 130,000 passengers travelling from the Midlands to London, and around the north-west.
Tube drivers have voted to strike after seeking triple pay and a day off in lieu for working December 26.
Keith Norman, the union’s general secretary, said: ‘It is painfully obvious to any reasonable person that Boxing Day is not an ordinary working day and, therefore, it is no surprise that Aslef members have reacted in the way they have.’