Talks with Acas failed to resolve the Aberdeen industrial action
Staff at First Bus in Aberdeen are planning further strikes in an ongoing row over pay.
The Unite union has held a series of meetings with workers to discuss escalating industrial action.
Workers have already staged a one-day stoppage earlier this month and are operating a strict work-to-rule policy.
A series of two-hour walk-outs are now scheduled to get under way from Tuesday. The company wants to impose a wage freeze this year.
First said a pay freeze was fair due to the current economic climate, and staff already being well paid.
But drivers, cleaners and garage staff are holding out for a 4% rise.
About 70% of those who voted backed the strike move.
Talks with the conciliation service Acas failed to find a resolution.
Similar strike action last year brought buses to a standstill before a deal was agreed.