Avon and Somerset Police closed the Lower Bristol Road in Bath at Rackfield Place outside the First depot after the crash at 03:00 GMT.
The A36 road closure, which was lifted at 14:00 GMT, had caused disruption and delays to commuters and bus services during rush hour.
Investigations are under way into how the collision happened.
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First said that while parts of its services had resumed a normal schedule, it would take a few hours for all services to return to normal.
Managing director James Freeman said: "We are hoping we will have a full service running in time for the evening commute.
"We would like to thank the public for their support and understanding and staff for going beyond their call of duty to help manage the situation and recovery."
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