Observator installed a Non-Invasive road sensor NIRS31 (of Firma Lufft) on a portal above the motorway A12 in The Netherlands. This set-up is a test in co-operation with Rijkswaterstaat (Department of Waterways and Public Works of The Netherlands). The test will last at least until summer next year.

During this test the data measured by the non invasive sensor will be checked with the data measured by sensors installed in the road surface on the same test site.

The measured data is being made transparent for both parties, by making use of our own online software program OMC-Data-Online.

The sensor measures the following parameters:

• Surface conditions such wetness, ice, snow and frost
• Water film height
• Ice percentage and determination of freeze temperature
• Friction

At the moment Rijkstwaterstaat measures temperature and salt concentration at 330 location in the surface of the main motorways. To be able to do maintenance or installation, they need to close down the road. This is not accepted any more. Also Rijkswaterstaat wants to measure more then just temperature and salt concentration. A new European Norm also mandates that additional parameters need to be measured to be able to monitor the road conditions. By optimizing road condition monitoring it will be possible to minimize the use of salt, which saves money and also the environment.

The measurement principle of this sensor (optical/spectroscopical): Water absorbs certain wave lengths differently. If there is a water layer on a runway or a highway, then the spectral characteristics are changed.