Baffled motorists have been forced to dodge a tree planted in the middle of a Melbourne road by an inner-city council.

Drivers and cyclists must swerve about half a metre around the sapling at Mater Street in Collingwood.

The diversion takes them close to parked cars on the side of the road.

Yarra City Council says the young tree was planted as a traffic calming measure, but residents fear it will become a hazard when it grows.

Last month motorists in the NSW city of Newcastle were left similarly puzzled when workers forgot to remove a power pole from the middle of a road.

It was left there after the road was widened and the kerb moved back.