More than 300 drivers are expected to walk out over 'fatigue concerns', according to the union.
Unite says that staff and patients could be affected by plans to move the service to Scarborough.
Staff at Arriva Luton are set to strike over allegations and the suspension of a union rep.
It comes amid accusations that Coventry City Council is guilty of strike-breaking attempts.
Councillor John Cotton urges the Unite union to reopen "realistic" negotiations in Birmingham.
Unite general secretary Sharon Graham says striking workers have the union's "unwavering support".
First Bus drivers in Doncaster are seeking pay parity with colleagues in Sheffield.
A judge rules the union repeatedly breached an injunction preventing the blocking of waste vehicles.
The union votes in favour of an "unprecedented" £580,000 cut, due to anger over ongoing action.
