Field tests have been conducted to evaluate the performance of a new remote optical sensor, the Vaisala Remote Road Surface State Sensor DSC111. The sensor can be installed on any post by the roadside or on a gantry across the road. It is based on the transmission of an infrared light beam onto the road surface and the detection of the backscattered signal at selected wavelengths. The sensor can distinguish between water, black ice, white ice, snow and slush. Determination of road surface state is based on measuring the separate layer thickness of water, black ice and white ice (hoar frost). Field tests were conducted in Finland, the UK and North America. The sensor's detection threshold for any type of ice is low enough to enable it to be used to directly measure slipperiness or grip in the form of a friction reading.
Samenvatting