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 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:
- Manually by placing a straight edge across a rut and measuring the distance from the bottom of the straight edge to the bottom of a the rut.
- Automatically, using a vehicle mounted non-contact multi-sensor transverse profile measurement device, e.g. laser profiling.