Sunbus has moved to reassure commuters that its fleet is safe, after two wheels fell off a bus on Queensland's Sunshine Coast while it was travelling.
The bus was travelling to the region's university with five passengers onboard on Wednesday when the incident happened.
No-one was hurt.
Sunbus says an investigation involving police and the Transport Department has concluded it was an isolated case.
Sunbus says it has conducted a full safety check of its entire fleet and identified no potential reoccurrences of the incident.
But Transport Workers Union spokesman Peter Biagini says it is not good enough.
"The bus was going around a roundabout - thank God for that because it was going around slower," he said.
"I would hate to have seen what what would have happened if those wheels fell off while it was going full-speed down the highway.
"These sorts of things shouldn't be happening."