ViaIRI

Texture and IRI measurement with high-speed laser.

General

The Texture Laser measures the pavement texture and height profile with a high degree of accuracy. By combining the height information from the texture laser with the Inertial Motion Unit (IMU), the International Roughness Index (IRI) is calculated. Other parameters, such as MPD and hilliness may also be calculated.

ViaIRI texture laser

The laser unit contains two sensors, a laser distance meter measuring the distance from the laser down to the road surface and a 3-axis gyro and accelerometer (IMU) 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, IRI and other parameters are created, one for each laser unit. Multiple laser units may be used to measure multi-track parameters.

The ViaIRI consists of the following parts:

  • One or more laser units with IMU placed on the front bumper or towing hook of the car
  • Odometer
  • GPS
  • An interface box placed inside the car in order to collect odometer signal and to distribute power and Local Area Network.
  • A windows PC used for data collection and data presentation.

Calculations

The measurement and calculations conform with ASTM E950, ASTM E1845 and World Bank Technical Paper 46 Class 1.

In addition ViaIRI supports Boeing Bump Index (FAA AC5380-9) and Ride Number (ASTM E1489)

Software

The ViaIRI user interface is based on the following:

  • Touch screen ready. The operator can start and 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.
Using ViaPPS Analyzer with ViaIRI measurements.

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

General, sensor unit
Operating temperature-10° to 60° C
Storage temperature-20° to 70° C
Relative humidity5-95% non-condensing
Power requirement12V, 20W
Laser
Laser typeRiftek RF607
Laser power< 80mW max
Laser class3B
Laser wavelength660 nm, (visible red)
Safety distance5.6 m
Measurement range250 mm
Measurement resolution0.025 mm
Maximum data rate70 KHz
Gyro
Accelerometer resolution1.9 µg
Gyro resolution0.22°/hour
Data collection
Laser sample rate70 KHz
Accelerometer sample rate2000 Hz
Gyro sample rate262 Hz
Odometer sample rate50 Hz
Measuring vehicle speed range20 - 120 kph