One of the key things good gritting services need to know is when to grit! It might sound simple, but getting it right helps the contractor to reduce costs and decrease any environmental impacts. This is where having a reliable and accurate Road Surface Temperature (RST) forecast can set a company apart.

Road Surface Temperature

Winter gritting is all about making sure your sites can be accessed safely through the winter months. This means making sure we know when ice will form and taking measures to stop this happening. The decision on whether a site needs gritting or not is often difficult as the RST can vary a lot from air temperature.

This is due to heat being absorbed by the road surface. During the day, heat given off by the sun and vehicles is absorbed by the road surface and then released over night. Effectively the road surface acts like a radiator, meaning the RST could be higher than the air temperature.

To complicate matters, there are a number of factors that can impact the RST. Shorter days and longer nights during the winter period means surfaces have less time to warm up and longer to cool down. Cloud cover at night is also a factor as they absorb some of the heat radiated by the road surface and re-radiate it back down. In simple terms, the clouds act like a blanket stopping the heat from escaping meaning the road surface stays warmer for longer.

Getting the right reading

So we know why the RST can differ from the air temperature, but what about taking accurate RST readings? As it would be impractical to install monitors at each individual site, it probably the most important aspect to getting a reliable, accurate forecast for sites spread all across the UK. The simplest solution would be to lay a grid over the map, splitting the area into sectors and take the average reading for that area. Basing your gritting visits on this might work well for some areas of the UK but for others you might encounter some issues.

To get the best forecasts, microclimates need to be taken into consideration. A microclimate describes a small-scale area with a distinctive climate, such as a valley, a stretch of coastline or an urban area. The weather variables in a microclimate, including temperature, may be subtly different to the conditions of the larger area as a whole. A good understanding of the UK climate is vital in order to understand and factor in microclimates. The Met Office, for example, takes readings at 2,700 forecast points across the UK and Ireland. These forecast points are used for areas that are most representative of the climate.

So as you can see, working out if your sites need gritting is not as simple as looking at the overnight temperature. Just because you see frost forming on your windscreen or the grass verges it doesn't necessarily mean the roads will be icy. All the work is aimed at ensuring your site are only gritted when they need to be. If you are looking for a winter services provider, always check that they use a reliable Road Surface Temperature forecast. If not you might be paying for gritting you don't need!

For more information visit  Mitie Landscapes