Drivers and engineers at First Bus in Essex are set to strike on Monday of next week.
Drivers at First Bus depots in Colchester, Clacton, Harwich, Braintree and Chelmsford and elsewhere will strike over terms and conditions.
Engineers will take strike action at the same time over pay. First Bus drivers in Essex struck at the end of last year over pay.
The workers’ Unite union has raised concerns about terms and conditions for existing and new staff that were not included within the agreement that ended the pay dispute.