Nevertheless, local measurement is required and must be as accurate as possible for assessing the potential slipperiness of a given section of road. Consequently, by measuring the salt amount and the water layer thickness it is possible to arrive at a reliable estimation of the freezing properties of the road surface. It measures surface water thickness on the pavement using an optical reflection method. The latter method produced more accurate human.
If we exclude the chemical component, this classification is the same as that used by the human observers. Water and ice layer thickness measurement principle at work in the DRS sensor. The capability to detect snow on the road is significant advantage: The results are shown in comparison matrices that are similiar to the Utti comparison matrices.
The results are shown in the comparison matrices of Figures 9, 1 and From the point of view of actual driving grip, however, it is essential to know the amount of the frozen substance on the road surface.
Laboratory testing has shown that the grip between tire and asphalt is dangerously reduced when the layer of ice exceeds 5 micrometers in thickness, Nicolas The Columbus method allowed the human observers to directly characterize the road surface state in the sensor s precise location.
Therefore, the DRS optical detector is able to measure the thickness of ice on the road surface although, in comparison with water layer thickness measurement, measurement accuracy is somewhat reduced due to the slight difference in optical properties. Although the actual grip will depend to a great extent on the condition of the tire and on the roughness of the asphalt, this laboratory result suggests that a small amount of ice can create slippery conditions. This is especially true of clear ice black ice.
Therefore, the DRS cannot measure actual snow thickness on the road surface, although it does accurately detect the presence of snow directly on the road surface. The height depends on the model:
Posted by: Kalar | on October 2, 2012
The freezing process of a solution containing a de-icing chemical and water begins at the so-called liquidus temperature and continues, if the temperature continues to drop, until the solution is completely frozen. The road weather station was located beside a two-lane main highway carrying an average of 8,7 vehicles per day. The temperature at which freezing begins is usually expressed as the depression of freezing point, DFP.
In this case, employees of Vaisala Inc. The disadvantage of this method lies in the lack of close observation of the road surface condition, which led to a greater error rate in the human at certain times.
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