As any seasoned motorist will no doubt be well aware, the roads can be particularly hazardous during the winter. Of course, inclement weather can strike at any time of year and it's important to be prepared for the various dangers you're likely to face as a driver all year round. However, the combination of wintry showers, low temperatures and icy conditions can be especially treacherous - which is why it's just as well we have an army of gritters and ploughs to help us get through the colder weather. But if you're not an expert on the subject, you might be wondering just how ploughs, salt and grit are actually deployed to help keep our roads clear.
According to BBC News, the substance commonly referred to as grit - which is laid on the roads to prevent them from freezing up - is actually rock salt. It serves to lower the freezing point of moisture on the road surface, thereby preventing ice from forming and helping to melt ice and snow which has already gathered. When particularly bad weather is expected, several patrols of gritters may be sent out each day, at staggered intervals. This should help to ensure that any disruption as a result of snow or ice is kept to a minimum, thereby making it easier for people to go about their business and reducing the number of accidents.
The amount of rock salt deployed also depends on the anticipated severity of the weather. If only a light frost is expected, then around 10g of salt per square metre should be sufficient. However, nearer 40g may be needed if heavy snow is forecast. The timing of gritting also requires careful consideration. For example, laying salt on the roads in the middle of the rush hour is hardly going to be practical, and may even cause unnecessary disruption. This is why you often see gritters going about their business in the evening and night time, when there are generally fewer vehicles on the road.
While most people use air temperatures as a reliable gauge, they are of less use to gritters. There can sometimes be several degrees' difference between the air temperature and the road temperature, and this is something that needs to be taken into consideration. Some gritting teams use a number of different devices - including GPS and road sensors - to help them get a clearer idea of what conditions are like. In addition, some routes take priority over others - while main roads are almost certain to be gritted ahead of snowy or icy weather, side roads will probably be left alone.
However, there may be times when the gritting teams are caught off-guard or snowfall is more severe than anticipated. This is when the snowploughs are sent in to clear the way. According to Wikipedia, snowploughs work by using blades to clear snow out of the way, depositing it to the side or pushing it straight ahead. Snowploughs are frequently used at major airports to help keep traffic moving, and they may often be used to ensure that emergency crews can access areas which have been cut off by heavy snowfall.