A bendy bus ended up stranded across a road in Sydney's northern beaches after becoming wedged on a median strip.

A witness told the ABC the driver of the State Transit bus tried to do a U-turn near the intersection of Avalon Parade and Barrenjoey Road in Avalon Beach about 8:00am.

A spokeswoman for State Transit said no one was onboard the bus at the time of the incident.

"Due to the turning vehicle's turning ability, the bus was unable to complete the manoeuvre and blocked all south-bound lanes and one north-bound lane of traffic as a result," she said.

"A State Transit mechanic attended the scene quickly and the bus was moved shortly after at around 8:30am.

"The driver involved was counselled and will be given additional training operating a bendy bus."

A sign post on the side of the road was removed temporarily to allow the vehicle to turn around.

No-one was hurt in the incident.

The Transport Management Centre said a mechanic was sent out to help move the bus.