（1） In winter, the method of throwing snow melting agent and mechanical snow removal is generally used for snow removal and antiskid. This method is better in the case of thin snow layer, and the snow can melt quickly. When the amount of snow gradually increases, it is easy to form compacted snow under the rolling of vehicles. In the process of continuous cooling, the road gradually freezes. After the formation of ice, the mechanical snow removal can only remove the surface ice and snow, and the speed of snow melting is greatly reduced. If the method of throwing snow melting agent is adopted, the mechanical snow removal has poor anti-skid effect, serious waste and poor anti-skid quality, which should be combined.
（2） Under the Expressway Overpass, due to the large temperature difference between the upper and lower deck of the large and medium-sized bridge, the temperature of the deck can generally be reduced by more than 2 degrees than that of the road surface. Under the same snowfall environment, the deck will freeze 2 hours earlier than the ordinary road surface. Due to the slow driving speed of vehicles, the phenomenon of skidding occurs in the curve and long steep slope, which is very easy to form ice. Due to the fact that the sunlight angle is mostly flat in winter, the road surface under the excavation section (shady place) and overpass is seldom exposed to sunlight, and the temperature is low. Generally, there is no ice on the road section, but ice has formed in these places. In addition, toll plazas and roads with large traffic flow will be covered with snow and ice. In this case, the automobile mechanical snow removal can only remove the surface snow, the ice on the road is difficult to melt into water, most of which disappear due to the change of time and environmental temperature, which needs a process. At this time, effective measures must be taken to remove the ice surface in time, but ordinary snow removal machinery is difficult to deal with the ice surface. The method of spreading anti-skid materials is used to solve the problem, but the use of snow melting agent will have a higher effect, but attention should be paid to avoid vehicle driving and wait for the snow to melt before releasing.
（3） Another situation is the early snow in winter. Due to the early snow, the ground temperature is relatively high. At the beginning, there will be some light rain. With the accumulation of time, the temperature will continue to decline, and the weather will gradually become cold. After 24 p.m., the road will quickly freeze. Although this situation is not too serious, because the temperature drops suddenly after the snowfall, the road will be frozen in a very short time It’s hard for human eyes to distinguish whether it’s frozen or not because of the black ice layer. Vehicles are easy to slip, and it’s easy to have a series of safety accidents. In this case, because the snow layer is too thin, the mechanical snow removal effect is not obvious, and the use of snow melting agent can see the obvious snow melting effect.