Salting FAQs

The county has the capacity to hold sufficient stock for an average winter. We will start the winter season at full stock capacity which is approximately 15,000 tonnes of salt.

A typical (non-snow weather conditions) gritting run uses approximately 200 tonnes of salt to complete the whole precautionary gritting network.

We have a constant record of how much salt we currently have and we are in contact with national suppliers to monitor deliveries. Stock levels are recorded on a weekly basis throughout the winter season and reported to Central Government. The stock information provided to Central Government has been used to ensure that deliveries of salt are distributed to the local authorities who are most in need of supplies to prevent authorities running out of salt at times of shortage.

It is responsible to have an emergency network agreed for use in the event of an emergency situation. A reduced network requires less staff, vehicles and salt to deliver. An emergency could be any type of situation which limits our ability to deliver a full network such as a fuel crisis, flu pandemic or salt supplies running low. The emergency network would not be introduced unless absolutely necessary. Before being introduced, all attempts would be made to publicise this change in service and keep the public informed.

Water freezes when it reaches 0C. Salt mixed with water or moisture lowers this freezing point. The colder the temperature and the more water present, the more salt is required to lower the freezing point. The effectiveness of salt begins to lessen at about -3/4C, and by -6C the quantity of salt required to remove snow or ice becomes ineffective. A small handful of salt (approximately 20g) can treat approximately 1m/3ft squared of cleared surface. If snow and ice have already formed on the roads and pavements, then adding salt will not help because there is no direct moisture for the salt to dissolve into. Snow and ice must be manually removed first.

Pre-salting areas before snow falls will not stop the snow from settling, but it will create a layer of moisture that will freeze at a lower temperature than the snow settling above it. This layer will reduce the risk of the snow bonding with the pavement, making it easier to remove.

If snow has compacted and bonded to the pavement and cannot be removed by hand, do not use salt on top of it. Instead spread cat litter, cinders or coarse graded/sharp sand (not building sand) or something similar over the area. This will become embedded in the ice and will make it safer to walk on.

It is not possible to provide an exact volume of salt we use each year, as spread rates per action vary depending on the weather and road conditions. The following is an estimate of tonnage of salt that was used last year: For Winter 17/18 - 108 runs and over 27,000 tonnes of salt used. (Note: This does not include salt used for secondary roads and footways).

The salting network consists of the following: 1) ’A’ roads that Essex Highways are responsible for. This excludes the A12, the A120 and the A130 which are administered by other organisations. 2) ‘B’ roads. 3) The primary road that links a rural settlement of over 50 houses to the main salting network 4) Roads served by at least 4 public bus services per day for 5 days per week or more. 5) Roads that link sites of national importance e.g. airports, ports, fuel refineries etc to the main salting network. 6) We also include roads which allow ambulance and fire stations access to the main salting network.

A decision to salt the roads is made based on weather conditions, road temperature and residual salt levels. We salt as often as is required and therefore do not have a standard number of runs that we do each year. The average number of runs for the last 5 winters was as follows: 13/14 = 51; 14/15 = 72; 15/16 = 49; 16/17 = 55; 17/18 = 108.

Decisions are made daily, based on local forecasts which give current weather conditions, predicted weather conditions, humidity, air and road surface temperatures and the amount of salt remaining on the roads. This decision is not taken lightly as each run uses approximately 200 tonnes of rock salt and costs include the salt, labour and fuel. From this information a decision is made whether to salt the roads and if so, at what time the gritting lorries should go out and how much salt to use. The decision is made centrally for the whole county and is published on our website. You can follow us on twitter at www.twitter.com/essexhighways. This site also provides general travel and traffic information for the roads of Essex. The gritting lorries are fitted with trackers and you can follow their progress on our website, as they travel along their routes.

The gritting lorries are instructed to go out based on weather condition information and road temperatures. We send the gritting lorries out before the surface temperatures fall and before or just after changing weather conditions. We also monitor salt levels that are already present on the roads. If sufficient salt remains on the road surface to be effective for the weather conditions, we may choose not go out. We also try to send the gritting lorries out ahead of peak hour traffic to ensure they are able to get around the network before the traffic builds up. This means that most salting runs are done either early morning and completed before 7am or late evening which may be why you have not seen the gritting lorries. Any further runs throughout the day are instructed as required.

No, we use rock salt. It is a common misconception that grit is used to treat ice and snow. From October 2013 we will be using a salt spreading system known as Pre Wetting. This applies salt particles covered in a liquid brine solution which means that the salt is distributed from the spreader in a more controlled manner than dry salt. This then starts working as soon as it hits the surface. Salt works by lowering the freezing point of any moisture that comes into contact with the road to -8C. If the road temperatures drop below this, the salt becomes ineffective and ice will begin to form.

All our gritting lorries are fitted with GPS tracking devices which allow us to monitor the vehicles progress against their prescribed route. This ensures that all vehicles complete their tasks and the network is salted as instructed. The trackers also enable the vehicle location to be displayed on our website. You can view where they are on the Track the gritters page.

Essex covers a large surface area and we also have a large coastline. The variations in temperature and weather patterns that can exist mean we have divided the county up into ‘weather domains’. The weather domains and a summary of the main areas within them are: West Uttlesford, Braintree, Harlow, Epping, Chelmsford and Brentwood East Colchester, Tendring and Maldon South Rochford, Basildon and Castle Point. When a decision is made, we consider the weather predictions for each area and instruct the gritting lorries to go out as necessary per area. When we publish the information on twitter we will use these area names.

Treating the roads and spreading salt does not guarantee that the roads will be free from ice and snow. Salt requires the friction of the traffic to work it through the snow. Salt works by reducing the freezing temperature of water. Snow and ice are solids which need to be broken down/melted by traffic movement. On quiet roads, there may not have been enough traction to ‘activate’ the salt. Our larger gritting lorries can be fitted with snow ploughs and are used as required to remove the heavy dumping of snow from the roads. The plough must have a clearance above the road to protect the road surface and to ensure the vehicle can manoeuvre around. This does leave a layer of snow on the roads. No guarantee can be given that roads will always be completely clear of ice or snow. On average our salting routes can take up to three hours to complete. If we are responding to a late change of forecast, or we have to wait for rain to clear before we can salt, road temperatures may fall by five degrees per hour causing wet roads to freeze before they are salted. 1) Peak hour snowfall - when rain turns to snow coinciding with peak hour. Early salting cannot take place as it would be washed away and the gritting lorries become delayed causing congestion. 2) Rain can wash salt off roads leaving them prone to re-icing. 3) In severe cold weather below -8 degrees even salt will not prevent ice from forming. 4) Dawn frost can occur on dry roads when early morning dew falls onto a cold road and freezes. It is impossible to forecast where and when this may happen. 5) It takes time for salt to become effective after roads have been salted.