While sections of Stud Road already have a bus lane, Roads Minister Tim Pallas announced last year the left lane between Boronia Road, Bayswater, and David Street, Dandenong, would operate as a bus lane on three-lane sections of the road "there is no signed parking to be impacted".

However, the changes have been slammed by Trevor Smith, managing director of transport company Tieco, just off Stud Road in Rowville.

Despite claims from the Government that there had been "extensive consultation which resulted in positive feedback", Mr Smith says he did not know about the lanes until he saw them constructed last month.

"Historically, Stud Road has struggled with traffic. It doesn't need to be retarded by a bus lane." Mr Smith questioned how practical the new bus lanes would be, saying drivers would be "chopping and changing" between two and three lanes of traffic.

The 901 SmartBus service, which operates from Ringwood to Frankston, travels along Stud Road.

RACV chief engineer Peter Daly said the RACV supported SmartBus, but understood the frustrations of drivers in having a lane of traffic taken away.

Scoresby MP Kim Wells said the extra bus lane would mean "absolute traffic chaos" for residents and commuters.

VicRoads did not respond by deadline.