We want to let you know about our plans for dealing with the winter maintenance on our roads, and you can find out information here on how our road gritting (Pre-Treatment and Reactive) operations are planned, the treatment resources we have, how we deal with Forecasting, Treatment Monitoring and Recording, the Treatment Materials we use, the Effectiveness of Salt, how we deal with our Footways, and what you can do to help such as the use of Grit Heaps and Grit Bins. We have provided information on severe weather conditions such as Dawn Frosts, Black Ice and Freezing Rain, and Heavy Rain and Snow Fall, and how we deal with them on our roads. You can also find out about the differences between our Council roads and the Trunk Roads, and read our Winter Driving advice for travellers.
The Roads (Scotland) Act 1984 provides the Council, as Roads Authority, with the duty to “take such steps as they consider reasonable to prevent snow and ice endangering the safe passage of pedestrians and vehicles over public roads”.
The Winter Maintenance Policy takes account of this, identifying the sections of the network where hazardous conditions are most likely to occur and with reference to population centers, public transport links and the location of resources, formulating a list of “Priority” routes. This includes routes on the main islands of Bute, Islay, Jura and Mull.
A review of Winter Maintenance operations was carried out in 2006 by a Members and Officers Policy Development Group, to review the department’s ability to provide a service within the confines of the Working Time Directive and Drivers Hours regulations. Adjustments to manning levels and times of various operations were introduced to produce the present level of service. The Winter Maintenance Policy agreed in October 2006 has been updated and adapted with service improvements each year and remains in place at present. A further review in 2010 of the resilience of the service, after the severe winters of 2008-9 and 2009-10, has resulted in amendments to sections 5-8 of the Policy, to include measures preserve salt supplies and maximise its efficient use.
The public road network of 2315 km, ranges from high speed A Class routes adjoining the Trunk road network through B and C class routes to a considerable length of single track roads, which all provide lifeline links to the population.
We are responsible for maintaining the road network and preserving accessibility throughout the winter months. Resources are mainly situated within the main towns, resulting in winter treatment routes of considerable length and a limited ability to move resources around in time of need. Operational plans are influenced by the requirements of the Drivers’ Hours Regulations and the Working Time Directive. The level of service achievable, given the dispersed nature of the population, dictates a priority of routes and variations in the pre-treatment time frames for each category of route. Despite these restrictions the current pre-treatment route network amounts to 52% of all public roads, however due to the peninsular type geography, most of these are “out and back” resulting in an overall efficiency of 48% on treated length versus distance travelled.
Road gritting (pre-treatment and reactive) operations
There are two separate elements to the Winter Service:
(1) Pre-Treatment of the Priority Network in advance of forecast hazards. Resources are made available ( including drivers on out of hours standby) to mobilise within agreed target times to prevent or remove hazards.
Pre Treatment Routes- Introduction and map of all routes
Mid Argyll, Kintyre and the Islands - Pre Treatment Routes
Oban, Lorn and the Isles - Pre Treatment Routes
Helensburgh and Lomond - Pre Treatment Routes
Bute and Cowal - Pre Treatment Routes
(2) Reactive treatments to recurring or persisting hazards, including precipitation (i.e. rain, hail, snow or hoar frost). The same resource (with assistance during normal working hours) re-treats the road network in order of priority until a hazard is removed. The reactive treatment operation routes are known as the Winter Route Category 4 (WRC4) tertiary network, and these are the routes next to or following on from the pre-treatment network where available resources will next be allocated. In some cases the reactive operations will start immediately after any Priority 1-3 treatments, if there is sufficient treatment material on board a vehicle, and it is deemed prudent to continue treatment. It should be noted however that, especially at the start and end of the season, hazards will have dissipated by daylight and further action may be considered wasteful. In long term persisting hazardous conditions, resources will progress through the network by level of priority and will eventually reach most roads, including the remainder of the roads not identified on the WRC4 maps, as resource capabilities allow.
The attached document shows the maps and descriptions of the Winter Route Category 4 network.
The Roads Operations Fleet includes 29 Econ Unibody multipurpose vehicles and 3 Bunce permanently mounted gritters, along with one sub-contractor, available to operate on the 31 pre-treatment routes and allow most of these to be completed within the desired 2 hour target. All these vehicles can be fitted with snow ploughs. Six routes, adjoining the Trunk network presently have two drivers allocated per day to provide a wider timescale for treatment, the remaining having only one operative on standby to react to conditions out with normal hours. However, there are several routes with a combined distance in excess of 130km which are difficult to treat to the above standard.
The attached document shows the vehicles that the Council has in operation for winter maintenance duties in each of the areas of Argyll.
The vehicle fleet and 37 drivers on standby , are managed and coordinated by 8 District Supervisors and 2 Managers. The management team is responsible for formulating the daily winter treatment plan, from the most up-to-date weather forecast. Winter standby operations are planned for the period 1 Nov – 15 April each season but can be extended as forecasts or conditions dictate. Out with normal working hours Drivers, Supervisors and Managers operate from home on a weekly 7 day shift basis, with all personnel changing at mid-day Friday, in normal circumstances.
The attached document shows the management and supervision structure within the Council for providing a 24-hour winter maintenance service.
Forecasting, Treatment Monitoring and Recording
We have 12 Road Surface and Weather monitoring stations situated throughout Argyll and Bute. Information is monitored by the management team through software operated and maintained by Vaisala Ltd, partners with the Weather Service Provider (WSP) MeteoGroup Ltd. The WSP produces 3 forecasts per day, covering nine different climatic domains and also specific forecasts for 8 of the weather station sites. This is posted on a special web site and reported by e-mail.
The attached document "Weather Forecast Domains and Stations" is a map of the weather forecast domains in Argyll and Bute, and shows the locations of the weather forecast stations
The management team formulates and issues a plan by 13:00hrs each day and this is distributed using a web based electronic system, Vaisala-IceMan. The team can access information in real time to record or monitor the progress of the plan. Treatment vehicles are operated by a single driver only for pre-treatments and supervisors monitor their progress by using the Cybit - Fleetstar satellite tracking system. Treatment runs are viewed on-screen in real time to provide a Health and Safety facility, information is archived for each vehicle and can be retrieved to confirm the general information on timing recorded in the IceMan system.
For further information on how we receive our forecasts and how we use the information to plan our winter maintenance service, please see the attached document "Weather Forecast and Monitoring"
Treatment of road surfaces to prevent or remove freezing is done by the application of 6mm crushed rock salt. This operation and the vehicles used, is commonly known as “gritting / gritters” but is more accurately referred to in the industry as “salting”. Salt can be spread at varying rates, ranging from 10g/m2 to 40g/m2 depending on the forecast or prevailing weather conditions. In circumstances of persisting heavy frosts or when snow accumulates the mix of materials will include “Grit” either in the form of sharp sand or fine crushed rock. The stockpiles in “Grit bins” and “Grit heaps” at the road side are of a similar combination of materials.
There are 9 mainland and 6 island salt stockpiles, with a combined storage capacity in excess of 10500 tonnes, of which only three at present are permanently roofed. In normal conditions this capacity equates to approximately 2/3 of the annual usage. A construction programme is planned for 2010-11 to increase the covered capacity from 5500 to 8500 tonnes which will allow closed season replenishment and result in environmental benefits by reducing losses due to precipitation. Due to the number of sites, weigh bridges are considered un-economic and a parallel programme is in place to procure all new vehicles with on-board weighing equipment. Salt usage and remaining stocks are recorded on a weekly basis and replenishment orders will be brought forward as necessary depending on operational requirements, and as the production and supply process allows.
Effectiveness of Salt
Rock salt prohibits water from becoming ice at Zero Deg. C. through a chemical reaction which reduces the freezing point. For this reaction to operate the solid salt crystals must go into a solution. In extremely cold but dry conditions the time for this reaction to occur may be considerably longer than if salt lands on a wet surface. In some circumstances it may there for be advantageous for a treatment to be carried out in a light drizzle, if clear cold weather is expected soon after. When temperatures drop lower than minus 6 Deg. C. , the chemical reaction reducing the freezing point of water becomes less and less effective. In such circumstances repeated “salting” may be wasteful, however the application of “grit” may provide additional traction to passing traffic by the mechanical action of the grit “grinding” the ice or snow under vehicle tyres. The relatively low traffic volumes on our roads mean that this could also take some considerable time to take effect, depending on the prevailing weather conditions.
Additional resources are available from within the department to participate in footway treatment operations in times of heavy snow or persisting freeze conditions. Due to the coastal location of the main towns there is no requirement for a pre-treatment programme for footways. In general, hazards are isolated and of short duration, the benefit in pre-treating far outweighed by the cost of the resources required to deliver a parallel footway service within the same timescale. Additional operatives from Roads, Streetscene and Refuse collection can be mobilized, during normal working hours, to treat persisting footway hazards, utilizing barrow gritters and specially adapted mowers with snow plough blades where available.
To find out more about our routes for treatment of footways, please see the attached document "Footway Treatment Routes"
Self Help - Grit Heaps and Grit Bins
Grit bins and roadside heaps are provided on routes which are not subject to pre-treatment or at strategic locations such as steep gradients or tight bends. They may also be located in urban areas to assist in footway clearance. These bins and heaps are provided to assist the public, please use them when necessary to assist in the clearance of public roads and footways. It should be noted however that in times of persisting hazards resources will be stretched, and it may not be possible to replenish all bins on request. At the start of the season, they will be filled with a 3 parts grit: 1 part salt mix; however if salt supply difficulties occur, as in previous seasons, only pure grit will be used to refill the bins.
“Flash Frosts” occur when the sun rises and thaws the roadside verges before the road surface itself. This means that moisture laden air comes into contact with the colder road surface to form a hoar frost. This frost can develop very quickly, within 10 – 15 minutes and they will form on top of dried rock salt left from an earlier treatment. The pressure of vehicles driving over this frost will cause it to melt and refreeze as ice on top of the salt. For the reasons given above regarding the lengths of routes, it is impossible to be in exactly the correct location to re-treat road surfaces as these conditions develop. Although a short lived phenomenon, drivers should be aware of this condition as it generally occurs around the morning “rush hour”
Black Ice and Freezing Rain
Black roads do not mean ice free roads. Winter weather can be variable and it is easy to get caught out by a sudden change. Black ice is extremely dangerous as it can be localised and not readily visible. Even in apparently mild conditions, the air temperature can be several degrees warmer than the road surface. In such circumstance even quite heavy rain can fall on to sub-zero road surfaces. This causes any previous salt to be washed off and then form a thin film of ice at the road surface. This is sometimes referred to as “freezing rain” and can cause severe disruption as repeated salt treatments are washed off immediately after application. In such circumstances resources can become stretched and the time to complete a successful treatment of the whole priority network can extend well beyond the target times. When these conditions exist only essential journeys should be undertaken as hazardous conditions could form anywhere on the network and could occur immediately after a treatment.
Heavy Rain, Snow fall and clearance
Due to the maritime aspect of Argyll and Bute, positioned on the Scottish west coast, the prevailing weather generally comes in over the Atlantic. This frequently means heavily moisture laden weather fronts passing over the country, sometimes with considerable speed. If the land temperatures have been reduced due to a period of clear cold weather the temperature difference on a warm front will cause precipitation to change from heavy rain to heavy snow as the showers make landfall. Heavy rainfall rates of 10mm – 50mm / hr are not uncommon. However this translates to ten times this depth if snow reaches ground level. Dry snow, with more air trapped within, can develop volumes three times greater than this. It is not uncommon there for to experience snow fall depths of 100mm-300mm for short durations as weather fronts pass by and depending on the moisture content, any pre-salting operations may very quickly become swamped.
Unlike pre-treatment for ice, snow has to fall on surfaces before it can be dealt with. The departmental resources detailed above are only sufficient to provide a pre-treatment facility against ice forming on the priority routes. Ploughing is only practical once snow depths approaching 50mm have been reached, until then salt and grit spreading will continue. When snow accumulates on the carriageway the hazard remains in place, unless a thaw develops, until it can be ploughed off. In all but single track roads snow clearance will automatically take at least twice the time of a salting run, as the ploughing vehicle must return to treat the opposite lane, however in practice, times can be considerably longer as ploughing speeds are dictated by the depth of snow, visibility, topography of the road and in some cases traffic volumes, much more than pre-salting. Generally grit will only be spread on the return trip, if snow has stopped falling, as most would be ploughed off otherwise.
In conditions where snow fall persists, available resources may be required to concentrate on the highest priority routes first until such time as there is an expectation that treatments will last. At this point the next priority routes will be treated, providing resources remain available. Unfortunately, these follow-on treatments can take a considerably longer time to achieve, if in the interim period, these roads have been driven on and any lying snow has been compacted.
Trunk Roads are the responsibility of the Transport Scotland, their appointed Management and Maintenance Agent for routes in Argyll is Scotland TranServ Ltd based in Perth. Whilst respective daily action plans are shared, these are based on different policies and there may be a difference in the extent and timing of treatments on Council routes where they adjoin the Trunk network. The Council has no agreement in place with Transport Scotland to use its resources to treat the Trunk Roads network.
Advice to Travelling Public - Take care
We endeavour to deliver as efficient a Winter Service, as prevailing weather conditions and available resources allow. However it is not possible to guarantee that all of a driver’s route will be completely treated. Drivers should take note of the prevailing weather conditions and any signs of potential road surface hazards and adjust their speed and driving style to accommodate potentially longer stopping distances and reduced visibility. Please be aware that there are differences in treatment policies and plans. This may result in a change of road conditions at the junctions of Trunk and Council roads.
Please drive carefully in Argyll and Bute.
Reporting roads faults ( including Winter conditions)
Normal Office Working Hours
Monday – Friday 09:00 -17:00 - Argyll and Bute Council ; Contact Centre tel. 01546 605514
Outside Normal Hours
17:00-09:00 overnight Monday – Thursday, Friday 17:00 – Monday 09:00, and Public Holidays
Roads and Lighting Faults ; R.A.L.F. , Tel. 0800 37 36 35