Road texture

Microtexture (MiTx) is the collaborative term for a material's crystallographic parameters and other aspects of microstructure: such as morphology, including size and shape distributions; chemical composition; and crystal orientation and relationships[1] While vehicle suspension deflection and dynamic tire loads are affected by longer wavelength (roughness), road texture affects the interaction between the road surface and the tire footprint.

Typically, road agencies do not monitor mix directly, but indirectly by brake friction tests.

Excessive MaTx increases rolling resistance and thus fuel consumption and CO2 emission, contributing to global warming.

Road agencies monitor macrotexture using measurements taken with highway speed laser or inertial profilometers.

Since MiTx has so short waves, it is preferably measured by dry friction brake tests rather than by profiling.

Profilographs that record texture in both left and right wheel paths can be used to identify road sections with hazardous split friction.

It is used by construction crews or certified consultants to measure the roughness of in-service road networks, as well as before and after milling off ridges and paving overlays.

IRI values range from 0 (equivalent to driving on a plate of glass) upwards to several hundred in/mile (a very rough road).

[3] Another type of profilograph system is for measuring the surface texture of a road and how it relates to the coefficient of friction and thus to skid resistance.

Macrotexture data can be used to calculate the speed-dependent part of friction between typical car tires and the road surface in both dry and wet conditions.

Road pavement profilometers (aka profilographs, as used in the famous 1958-1960 AASHO Road Test) use a distance measuring laser (suspended approximately 30 cm from the pavement) in combination with an odometer and an inertial unit (normally an accelerometer to detect vehicle movement in the vertical plane) that establishes a moving reference plane to which the laser distances are integrated.

IRI values range from 0 (equivalent to driving on a plate of glass) upwards to several hundred in/mi (a very rough road).

Another type of profilometer is for measuring the surface texture of a road and how it relates to the coefficient of friction and thus to skid resistance.

Macrotexture data can be used to calculate the speed-depending part of the friction number between typical car tires and the road surface.