Rutting is the longitudinal vertical deformation of a pavement surface in a wheelpath, measured relative to a straight edge placed at right angles to the traffic flow and across the wheelpath, with a length/width ratio greater than 4:1.
A single instance of rutting is called a rut or wheel rut. Large ruts can hold enough water to result in vehicles aquaplaning in wet weather.
Rutting can occur in both sealed roads and unsealed roads.
Rutting is measured in millimetres. AustRoads guidelines express a preference for rut depth to be reported with reference to a 2 metre straight edge, with a depth reading to be taken every 100 metres.
This measurement can be obtained in a couple of ways: