In general terms effective Winter Maintenance consists of applying precautionary treatments to the road surface in advance of predicted snow and ice conditions. This precautionary treatment is achieved by spreading salt on roads and footways to prevent the formation of ice, commonly referred to as “gritting”. The most practical de-icing material for use on Aberdeenshire’s roads is 10mm Rock Salt, this is a graded material supplied in accordance with the appropriate national standard, BS 3247:1991. Depending on particular circumstances a salt/sand mix may also be used. In addition to precautionary treatments it is also necessary to react to weather events by carrying out further gritting if ice reforms on the road surface and ploughing snow to clear roads following moderate or heavy snowfalls.
- Planned treatment map
- Precautionary treatments
- Post event treatments
- Priority routes
- Secondary treatments
The map shows which roads in Aberdeenshire will receive gritting treatment. For live updates on trunk roads treatment (A90 and A96 in Aberdeenshire) visit Traffic Scotland website.
These are the application of de-icers to road surfaces before the onset of freezing conditions (that is frost, snow or freezing rain).
The purpose of precautionary treatments is to prevent the formation of ice, or to weaken or prevent the bond of freezing rain or snow to road surfaces.
It is usually impractical to spread sufficient salt to melt freezing rain or more than a few millimetres of snow. Therefore, in advance of forecast snow or freezing rain, salt is spread to provide a debonding layer so that:
- snow is more readily removed by ploughing
- compacted snow and ice are more easily dispersed by traffic
It is very difficult to remove a layer of compacted snow or ice that is bonded to the road surface, so precautionary treatments are essential before heavy snowfall.
The majority of winter service treatments (and salt spread) in the UK are precautionary treatments in response to predicted frost conditions. The spread rates used are dependent on the condition predicted.
In an average winter Aberdeenshire Council would typically carry out in the region of 200 planned precautionary treatments on our Primary Treatment Network (extending to around 1,000 miles of our A and B class roads), typically at a spread rate of 10g/sq.m. This level of treatment alone requires approximately 25,000 tonnes of salt per season.
Post event treatments involve the ploughing of snow that has fallen and the application of de-icers (salt) and abrasives (sand) to ice and snow present on the road surface, or some combination of these.
Although de-icers will melt ice or snow directly, it is normally impractical to apply sufficient quantities of de-icer to melt all of a moderately thick snow layer. Ploughing is the only economical, efficient, effective and environmentally acceptable way to deal with all but very light snow.
We have to prioritise which routes are gritted and ploughed owing to the vastness of our road network. This means that in times of severe winter weather there may be a delay before we are in a position to treat more minor roads and residential streets.
We maintain a road network totalling approximately 5420km (3370 miles) in length, 10.3% of the non-trunk road network in Scotland. It is impractical to provide a precautionary treatment to all of the roads in Aberdeenshire, therefore we have developed a Primary Treatment Network consisting mainly of “A” class and other busy roads linking our communities. This network is made up of 32 different gritting routes, operating from 14 council depots located throughout Aberdeenshire and covers approximately 30% of our total road network.
All roads not included in the primary route network may receive reactive treatment, should prevailing weather forecasts indicate that snow or ice conditions might be expected to persist for a period in excess of 48 hours.
With regard to footway winter treatment it is important to recognise the finite resources that are available to the Council. As with the carriageway network, it is not possible to prevent frost or ice forming on all footways. In order to target resources a hierarchy of footways has been developed in order to prioritise the busy town centre areas where there is most pedestrian traffic.