Road Roughness Meter


Range of Use

Roadmaster Road Roughness Meter is a device used to measure road roughness, based on the IRI measuring principle developed by the World Bank. Roadmaster system consists of a central unit, one or two accelerometers, an odometer or a DMI and a laptop pc. It can easily be installed in practically any vehicle - a car, van or truck.

Roadmaster can be provided with a GPS device and location data (latitude and longitude) is saved together with the IRI values, if desired.

Measuring principle

An accelerometer installed on the rear axle near the right wheel (and the right wheel path) measures its vertical acceleration. By using double integration this is converted to vertical movements of the rear axle and thus to the longitudinal profile of the road surface within certain wave lengths.

The longitudinal road profile is used as a input in the IRI equations. The driven distance is measured from the pulses from a DMI (optionally speedometer output of the vehicle).

As a result an IRI value is calculated for each 100m.

Roadmaster can be calibrated against the known road profile or Golden Car. In practice we have found out that Roadmaster results typically differ less than 5 to 10 % from an accelerometer-laser instrument based Road Monitor System which is used in Finland.

Roadmaster UI

Technical specifications

Measuring speed 30 to 100km/h (preferably 80km/h)
Sampling interval <2.5cm
Saving interval 100m (optionally 5, 10, 20, 50m or custom interval)
File format Plain text, human readable
Roughness accuracy +- 0.5 mm/m (Class III)
Roughness correction to true IRI Yes (can be calibrated with a "true IRI device")
Distance accuracy > 0.1 % with a DMI
Roughness units IRI (mm/m) or BI (mm/km)
Data storage capacity Depends on the PC hard disk, >100000 km (practically unlimited)
Roughness sensor An accelerometer attached on the wheel suspension, optionally two accelerometers (left / right)
GPS protocol NMEA 0183 (non standard / proprietary messages / protocols by request)