As winter sets in, you may notice more and more gritting lorries out and about on the road. But you be wondering what exactly do the gritters lay on the road, and how do they clear the snow and ice away? We have spoken to a specialist Gritting Company to dispel six myths about road gritting. Sit tight, and take a non-skidding drive through some of the myths.
Myth 1: The winter wagons contain grit.
Untrue. The gritting lorries you see out on the road actually drop salt, and not grit.
Grit can block drains when washed away, and actually creates a sticky, slippery residue on the surface of the road. The alternative is salt.
White salt is expensive and is often used in the grounds of schools, hospitals and business parks, as it leaves less residue on floors and carpets when trodden in by pedestrians.
The salt used on roads is brown rock salt, which is often mistaken in it’s appearance for grit. Due to its more economical price, it is generally used on larger areas and roads instead of it’s white counterpart.
Myth 2: Salt will melt ice at any temperature.
Not true. Salt works by lowering the temperature at which water will freeze, preventing ice forming on the road surface. When salt is spread on top of ice or snow, it will begin to melt the surrounding ice. When melted, a salt and water substance is created which will then spread to other areas.
By using a higher concentration of salt, the freezing point will be lower. However salt is less effective below minus five degrees Celsius. At lower temperatures, ice and snow treated with salt will not melt as fast.
Myth 3: Once the salt has been spread on the road the ice will melt immediately.
False. The de-icing effect of using salt on the road relies on the salt being crushed and spread by passing vehicle’s tyres. This is why it is more common to see gritting lorries targeting busy roads than side roads due to the higher volume of traffic passing over and spreading the salt.
Myth 4: Deep snow on roads will melt quickly with salt spread on it.
Not true. Salt works best on snow that is less than 4cm. It is more common to see ploughing on roads with deep snow, with grit being applied afterwards to help remove the ice and snow.
Myth 5: Gritting is pointless if it snows after it is laid.
False. Grit works both ways. If there is a layer of snow on top of salt, then it will begin to melt the snow and ice from below. This is helped if traffic can help spread and melt the ice from other areas.