Find out about road gritting

Myths and facts of gritting

How many gritters and ploughs do Swindon Borough Council (SBC) have?

We have nine gritting lorries, eight of which are in regular use and we generally keep the ninth as a spare in case of a breakdown. We’ve also got eight ploughs. 

How many members of staff are involved in gritting activities?

There’s no-one in the Council’s Transportation Team who works on gritting full time. All gritting staff fit their work in around their other council full time jobs during the winter season (mid-October to mid-April).

There are two main teams of trained and qualified gritter drivers made up of eight drivers each, who are on standby 24-hours-a-day for gritting operations every other week. 

There is a team of five inspectors to oversee the gritting operations and act as eyes and ears for the decision makers during the night.

The decisions whether to go out gritting and monitor forecasts and conditions is made by a team of officers who are also on duty 24 hours a day during their rostered weeks.

When snow ploughing is necessary, there is a need to have a ‘mate’ with each driver. In these cases we have to rely on the good nature of any available staff to assist as ‘mates’.

How do SBC decide gritting treatments? 

Swindon Borough Council has two forecasting weather stations, one near Blagrove Roundabout on Great Western Way and one on Marlborough Road, just outside Chiseldon. Readings of the current weather conditions are sent from both stations to our specialist Weather Forecast provider every 10 minutes. These readings produce two daily forecasts which show the forecast air temperature, road surface temperature, wind speed and rain/snow. If there’s any uncertainty in the information received, we call the forecaster. 

From this information, gritting treatments are planned. If there’s any major changes to the forecast at any time of the day, the forecaster calls the decision maker to let them know. Additionally, a two to five day forecast is received daily to help us plan ahead for what gritting resources may be needed. 

Why haven’t I seen any gritters out and about? 

We have eight gritting vehicles to treat the 322km of road included on our gritting routes and it takes approximately three hours for one vehicle to treat its entire route. The vehicles normally start gritting at least four hours before the forecast says that the road surface temperature is to reach freezing point. If it has snowed, it’s likely that the gritters will be on the road continuously, but it may be three to four hours before they pass the same point twice as they will have to return to the depot to be refilled with salt. When heavy snowfall occurs, our priority is to keep the strategic network open. The gritters will be concentrated on the main roads and fitted with snowploughs, meaning that estate roads may not be treated as often. 

Why do gritters sometimes drive without spreading salt? 

Although it may look this way, the gritting vehicles we currently use are far more sophisticated than those of years gone by. The lorries now dispense the required amount of salt directly down on to the road. 
However, sometimes a vehicle might not be spreading any salt if it: hasn’t reached the starting point of its treatment route; is returning to the depot to refill; or is driving over a section of road which has already been treated by a fellow driver to get to the next part of their route. 

Every gritting vehicle is fitted with a GPS system which tracks its route and speed, and it’s part of the inspector’s job to make sure the lorries don’t deviate from their route. 

Why has a salt bin near me never been refilled? 

We locate bins in the most hazardous areas, looking at the gradient of roads and pavements, speed of traffic, whether there’s a safe area on public land for the bin without causing an obstruction as well as anyone in the local area who would be able to spread the grit. A list of all salt bin locations can be found on our Salt and grit bins locations webpage.

Who is responsible for the M4 and A419? 

The A419 and the M4 are both treated by contractors on behalf of Highways England. There is a list of all of their contracts available on the Highways England website.

Why don’t pavements in Swindon get gritted?

There are in the region of 1900km of pavements, alleyways and cycle paths in the borough and with the best will in the world it would simply be impossible to treat them all. There are around 500 salt boxes available across the borough and this salt can be used by residents on pavements and pedestrian areas.

When and why do SBC ‘handsalt’ roads?

All our programmed gritting routes are designed so that we can access the roads using one of our gritting lorries. When we experience severe snow conditions we try to attend other roads, particularly those on hills. However, due to accessibility or safety concerns sometimes we cannot use our gritting lorries. In these cases, we send smaller vehicles loaded with salt which is then spread by hand by our operatives. We usually concentrate on roads for treatment, but when handsalting steep hills, the operatives do apply salt to the footways to improve safety for pedestrians.

When do SBC decide that the plough should be used?

Contrary to popular belief, we cannot scrape snow ploughs along the road as this would just wear the rubber blade out within minutes. Instead the ploughs are set to run about one inch above the road surface, meaning we need to have at least two inches of snow on the road before the ploughs are used.

How does salt prevent the formation of ice?

Salt lowers the temperature at which water freezes, helping to prevent ice or frost forming on the carriageway. However, if temperatures were to fall below -10 degrees centigrade, salt generally loses its effectiveness. 

Does spreading salt on top of ice or snow melt it straight away? 

Salt will not melt ice or snow straight away. It takes time for the salt to mix with the snow and ice and melt it. However, cars driving over the snow and ice will speed up the process because it mixes the salt in faster.

What type of grit do SBC use? 

For our normal salting operations, we use a product known as Thorox+. This is rock salt generally mined within the UK with the addition of a by-product derived from the sugar refining process. There are several benefits to using this product as opposed to the traditional pure rock salt including:

  • It’s less corrosive to steel and aluminium
  • It causes less damage to concrete and asphalt road surface
  • It’s more free-flowing which makes it easier for the gritting equipment to spread without it blocking up the mechanism
  • It remains active on the carriageway surface for longer so we do not have to treat it as often

If we have to treat structures like footbridges, we can’t use the normal Thorox+ salt because, even though it’s less corrosive than pure rock salt, it could still damage the reinforced concrete structure. In these cases, we spread a product which contains urea as its active ingredient which is much less corrosive. We can’t use this urea product as our main de-icing material though, as it costs about 16x more per tonne than the Thorox+.

How much grit is used and how much does this cost?

It takes 25 tonnes of salt to treat all the main routes in Swindon during freezing weather, and more than double that when it snows. It costs around £5,000 for all vehicles and drivers to carry out a night’s operation so it’s important we only do this when we definitely have to. 

What distance of road do you cover when gritting? 

We concentrate on treating the routes that are most heavily used, which in Swindon is around 320km of roads. Swindon has over 800km of roads in total, so those which aren’t treated require extra care when the weather is bad. While we do our best, we cannot guarantee the routes we do treat will always be free of ice so if you see a problem, please let us know via the Report a Problem with Road Gritting webpage.

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