Dorset Highways carries out precautionary salting of the network to prevent the formation of ice, as well as salting to remove snow and ice from the road network.
6mm dry rock salt is used for precautionary and post event salting. Grit sand is added to the salt or laid on its own to aid traffic movement during heavy snowfall.
Weather forecast
An effective and efficient winter service is only possible with reliable and accurate information about weather conditions. Dorset Highways utilises the best weather information available from its weather forecast provider, currently Meteo Group (DTN), to ensure that decisions are based on the most accurate data available.
During the winter service period Dorset Highways receives detailed weather forecasts and reports specifically dedicated to the roads, four weather domains and the 22 routes within the Dorset council area. This data is based upon national weather forecasts and the data collected from 11 roadside weather stations positioned across the county.
The timing of precautionary salting depends upon the prevailing weather conditions and will be arranged to ensure the network is treated before ice and frost form.
Experienced members of staff from Dorset Highways will act as Duty Engineers throughout the operational winter service period on a rota basis. The Duty Engineer is responsible for:
- receiving forecast information from the forecast provider
- monitoring current weather conditions
- issuing salting instructions for the precautionary network based on the and the 22 precautionary routes. Posting the forecast decision on the Icelert Bureau and on the Meteo group (DTN) system
- assisting and advising during snow events and severe weather events
- convening the Extreme Weather Event Board
- establishing liaison/contact with Dorset Police Control Room
- participating in any teleconferences convened
When we salt
Precautionary salting will take place on the scheduled network on a pre-planned basis to help prevent the formation of ice, frost and / or the accumulation of snow on carriageway surfaces.
Post salting will normally take place on the scheduled precautionary salting network to treat ice, frost and snow that has already formed on carriageways. Post salting may in exceptional circumstances also be carried out on roads or sections of roads beyond the scheduled precautionary salting routes.
Spot salting may take place on parts or sections of the scheduled salting routes either to help prevent formation of ice, frost and / or accumulations of snow or as a treatment to ice, frost and the accumulation of snow that has already formed on the carriageway. Spot salting may in exceptional circumstances also be required on roads beyond the precautionary salting network.
Instructions for precautionary salting of the network will be issued if road surface temperatures are expected to fall below 1ºC unless:
- road surfaces are expected to be dry and frost is not expected to form on the road surface
- residual salt on the road surface is expected to provide adequate protection against ice or frost forming
Instructions for salting of the precautionary network will also be issued if snowfall is expected.
The Duty Engineer will issue the instructions for precautionary salting of the network for each of the 22 precautionary routes. Any instructions for post and spot salting will be posted on the Icelert Bureau and on the Meteo group (DTN) system.
The Duty Engineer will issue instructions to pre-salt the Community Routes if snow is forecast or if temperatures are expected to fall below freezing for a prolonged period. These decisions will also be posted on the Icelert Bureau and on the Meteo group (DTN) system. There is an expectation that pre-salt action on the Community Routes network would be completed within six hour of the action being called.
The Precautionary Salted Network will be fully treated within 2.5 hours (20g per m2 spread rate or less) of instructed start time.
When an urgent instruction to treat the precautionary network is issued by the Duty Engineer then the treatment of the network will start within 1.5 hours.
Salt stocks
Salt stocks will be replenished before 1 November each year, with 13,500 tonnes in stock across five depots. Minimum stock levels (5,800 tonnes) are maintained throughout the core winter service period.
Dorset Highways will arrange for the Stock Control Spreadsheet, held within the winter service and emergency folder on the highways computer server. This is updated following each treatment of the network. Dependent on usage salt stock levels will be replenished as required to ensure minimum stocks are held. This will be subject to the control of the Governments ‘Salt Cell’.
Our salting routes
All A, B and well-used C class roads are treated, as well as:
- links to hospitals, large industrial estates, transport interchanges, emergency services (including manned Coastguard and RNLI) stations and identified critical infrastructure
- routes to all urban schools with more than 500 pupils and rural schools with more than 350 pupils
- primary bus routes with a substantial frequency (school bus routes are not included)
- main routes (that don’t meet criteria above) through towns and villages with populations of more than 750
Consideration will be given to salting diversion routes where interruptions to the precautionary network have occurred.
The aim of this criteria is to treat the roads used by the majority of the travelling public this amounts to around 28% of the overall Dorset Council road network.
Secondary network
During prolonged periods where temperature remain at or below freezing community link routes – serving smaller villages and hamlets – will be treated as resources allow.
These routes will also be pre-treated – where resources allow – when snow is forecast and will be ploughed and salted following snowfall once priority ploughing routes remain clear.
Footways and cycleways
There is no precautionary salting of footways, pedestrian precincts or cycleways by Dorset Highways as it is impractical and financially draining to carry out.
However, there is a certain amount of salt overspill onto footways and cycleways when precautionary salting is being carried out on adjacent roads.
Post-salting of footways and cycleways will be carried out on a priority basis during severe weather as resources permit.