The objective of this study was to test the accumulation of snow forecast (hereinafter called the “Pilot”) developed by Foreca. The Pilot, the object of study, forecast the depth of snow by road section for the following 24 hours and reported the actual accumulation 12 hours backwards. The study monitored the development of snow depth by means of field measurements conducted in various parts of the pilot area and compared the results with the forecasts and actual snow accumulation reported by the Pilot.
The accumulation of snow increases in the model during snow fall (figure 1). When new snow have not falled during measure carrying time, the accumulation will reset. The line indicating the accumulation will turn to orange, when the accumulation reaches the ploughing threshold. The line turns to red, when the maximum snow depth is exceeded. The corresponding colours is seen also on the road map. The idea behind the Foreca Pilot is, that it makes easier to manage broad road networks in situation, where the snow fall intensity and quality requirements vary in the area.
Figure 1. Snow forecast pilot user interface. The view in situation, when the user have clicked a single road section.
In the study, the development of snow accumulation was measured and monitored in nine different snowfall situations in various parts of the pilot area at the beginning of 2017. Of these, the last seven measurement situations are described in detail in the report (table 1). The snow depth measurements were conducted at different points of the carriageway cross section, and in spots in natural state outside the carriageway.
Table 1. The summary of the measurements described in the report.
The study showed that the Pilot had usually forecast a significantly higher snow accumulation just before the snowfall began or still while it continued than what the Pilot reported as actual snow accumulation afterwards. On the other hand, as a rule, the snow accumulation established by the Pilot was quite close to the results of the field measurements. The difference between the Pilot forecast and the actual snow accumulation may have been at least partly related to the fact that the forecast did not take into account the potential melting of snow during snowfall. The snowfalls targeted in the study were generated when the temperature was about zero degrees centigrade or slightly below that.
Almost without exception, the largest snow accumulation rates were measured on the edges of the road. Here, the edge of the road refers to the part of a paved road at about where the edge line is located. The study also showed that snow accumulation on the edges of the road corresponded relatively well with the spots in natural state. Therefore, the highest snow accumulation rates on the carriageway cross section corresponded relatively well with the actual accumulation reported by the Pilot.
Taking into account that, at the moment, the entrepreneur and the customer for winter management lack any low-cost, comprehensive, and accurate assessment tools for assessing snow depth in large areas, the Pilot can be considered a potential tool for the assessment of snow accumulation. Moreover, it is worth noting that, in technical terms, the Pilot functioned almost flawlessly throughout the study. The user interface is very clear, easy to use, and intuitive.
The whole rapport (in Finnish) can be found from Finnish Transport Agency website.