Two-thirds of bus services in Greater Manchester, including school buses, will not run from Friday as about 2,000 drivers go on strike over pay.
Transport for Greater Manchester has warned passengers to plan ahead for the strikes, which are set to last until Monday, with tickets being accepted on trams and some trains instead.
Chief network officer Danny Vaughan said while services in Wigan and Bolton would still run, “most of south Manchester and East Manchester will be very badly affected”.
He said: “There are alternatives for people but they’re better off planning ahead and checking on our website to make sure that they can they can get around it when needed.”
The Unite union said drivers working for various operators under the publicly controlled Bee Network have rejected pay offers ranging between 3.5 and 6% after months of negotiations.
Regional officer Colin Hayden said: “The strikes this week, as well as the further action we have called, will cause travel chaos in Greater Manchester.”
Unite has said further strikes involving Stagecoach, First Bus Rochdale and Metroline staff on Manchester’s Bee Network would take place from 30 September to 2 October in addition to this weekend if an agreement is not reached.
Metroline Manchester, Stagecoach Manchester and First Bus Rochdale said they were committed to finding a resolution.
Mr Vaughan said: “Unfortunately for us we can’t step in and intervene directly, so pay is a matter for the bus operators with the union.
“We’ve been encouraging them all through the pay talks process to try to find an arrangement.
“Our primary concern is passengers and it’s really disappointing to see strikes the first time on the Bee Network.”
A full list of affected bus services can be found on the Bee Network website.
