General
The Texture Laser measures the pavement texture (MPD) with a high degree of accuracy. By combining the height information from the texture Scanner with the Inertial Motion Unit, the International Roughness Index (IRI) is calculated.
The laser units contain two sensors, a laser distance meter measuring the distance from the laser down to the road surface and a 3-axis gyro and accelerometer used for measuring the movement of the laser unit itself.
When the car is moving and measuring, data is collected from the laser units and stored by the PC. When the measurement is complete, the stored data is analysed and the longitudinal profile and IRI is created, one for each laser unit. MPD may also be calculated for each laser unit.
The ViaIRI+ consists of the following parts:
One or more laser units placed on the front bumper of the car.
Odometer.
ViaIRI+ texture laser.
An interface box placed inside the car in order to collect odometer signal and to distribute power and Ethernet.
A windows PC used for data collection and data presentation.
Longitudinal profile
The ViaIRI+ produces a longitudinal profile of the road. The profile is intended for IRI calculations and contains wavelengths of 50 meters or less. The profile is calculated for every 0.25 meter of the road.
IRI, International Roughness Index
ViaIRI+ calculates the IRI number from the longitudinal profile.
MPD, Mean Profile Depth
As an option, the ViaIRI+ may calculate the MPD for the road surface. The calculation of MDP requires high speed data collection, see technical data for more information.
