Texture and IRI measurement with high-speed laser.

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
• 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.

Software

The ViaIRI user interface is based on the following:

• Touch screen ready. The operator can start en end measurements using touch screen interface.
• Easy to operate. Large fonts and few numbers make it easy for the operator to observe the measurements when the measurements are being performed.
• Background verification of measured data. The user interface checks the data from the sensor unit ensuring that the stored data is valid.
• The user interface may also show live IRI and MPD if the IRI and/or MPD options are selected. Notice that the live data only will give an indication of the value, as they may differ slightly from the data calculated after the measurement. This is due to improved filtering when the measurement is completed.

All the sensor data is saved in an internal database. The report generator produces reports in .csv or .xml format, which can be easily loaded into Microsoft Excel for further analysis. The reports may also be provided in a custom format. The report contains information about the date the measurement is performed, location, system name etc. Lastly, there is a list of rows containing calculated values for a given distance.

The Analyzer shown to the right may be used to give a graphical presentation of the test results. This program makes it easy to analyse one measurement, or compare several measurements. The image shows three different measurements of longitudinal profile for the same road segment.

Technical specifications