A new speed camera on a Wellington motorway is being switched on just in time for the Christmas rush.

The camera between Horokiwi and Petone was installed in October, but will start operating today.

Acting Wellington District Road Policing Manager, Senior Sergeant Ian Martin, says the stretch of road is busy during regular weekly traffic, and peaks during holidays.

He says the new camera will encourage motorists to slow down before they reach the Petone exit, and a tight curve which goes under an overbridge.