Road eye sensor
Road eye sensor with a diameter of 6-7 cm

Road eye (RE)/Intelligent Road (IR)

The Road eye sensor is an optical sensor for road condition classification on vehicles. The sensor consists of three laser diodes and a photo detector. As different phases of water (wet, ice and snow) reflect light differently due to absorption and scattering it is possible to draw conclusions from the Road eye measurements regarding road conditions and the surface roughness.

Classification of different road conditions is mainly based on the differences in absorption between the three wavelengths. The surface roughness is mainly based on the changes of intensity levels for one wavelength, respectively. Within CASTT there is two different projects where the sensor is utilized:

Road eye (RE)

The aim of the project is to use the Road eye to characterize winter road conditions in terms of surface material and structure that can be used by the automotive and automobile test companiesto increase the repeatability in vehicle testing.

The inventor of the Road eye sensor

Sten Löfving Optical sensors


Intelligent road (IR)

The aim of the project is to use the Road eye to characterize winter road conditions and use this as feedback to road condition forecasts to investigate the possibility to improve road weather and condition forecasts.


For vehicle testing repeatability is important, as a lot of vehicle testing is carried out outdoors the weather will play a part in the conditions of the testing. By classifying the road condition during the test it is possible to get a better picture of how the weather condition has affected the tests.

Measures of a test track.jpg
Measures of a test track during a day of sunny weather. It can be seen in the figure that as the sun shines on the asphalt the snow turns in to ice and the snow dragged out on the asphalt turns in to water, blue markings.

For road weather and condition forecasts it is important to map the road conditions to a position to get a good image on where slippery road conditions appear. 

Road Condition Classification

Video of logged and positioned road condition data. Red=ice, yellow=snow, blue=wet asphalt and black=dry asphalt.

For real time data go to:

I media

Mobilappen som varnar för halka – i nästa kurva

SR 8 okt 2012


Johan Casselgren berättar om halkvarnare

SVT 20 okt 2012



Major road safety award to Johan Casselgren at LTU



Johan Casselgren


Project leader: Johan Casselgren

The Road Eye research project is funded by the European Regional Development Fund's AVTEC project.

Sidansvarig och kontakt: Ted Karlsson

Publicerad: 23 januari 2012

Uppdaterad: 26 november 2013


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