Winter
Gritting Routes 2009/2010 (PDF 1Mb)
We salt the highway network to help the safe movement of all
highway users, buses, cyclists, motorists and pedestrians. It is
important in terms of both road safety and economy. Our winter
maintenance policies follow the principles set out by the Local
Authority Association's publication 'Code of Practice for
Maintenance Management - Delivering Best Value in Highway
Maintenance'. We spread salt to prevent ice from forming
on 950 kilometres of our roads network every night when
frost or icy conditions are forecast.
Our aim is to ensure that salt is spread on the highway before
ice forms. We achieve this by using a fleet of 16 gritters,
which are strategically based across the Cheshire West and Chester
area. These gritters spread about 11,000 tonnes of salt onto the
highway network in an average winter, the gritter fleet are
equipped with GPS tracking to enable
accurate monitoring of where they are and which roads have been
treated. Salting is normally completed within four hours and
usually before 7.00am.
With 2,253 kilometres of maintained roads, it would be
prohibitively expensive to treat the entire network. 950 kilometres
are normally treated, i.e. about 42% of the network. The Government
Highways Agency is responsible for salting all trunk roads and
motorways in the Cheshire West and Chester area.
Roads which are salted are dealt with in the following priority
order:
Priority 1 Routes
are all ‘A’ Class carriageways, and designated routes to A & E
Hospitals. Then in order to maximise efficiency and scale of
economy, other classes of carriageway which are required to be
driven as part of the route, in linking up the ‘A’ Class network,
will also receive this level of treatment. These will be as
identified on the Winter Gritting Route Plans;
Priority 2 Routes
are other major commuter roads (‘B’ class), major
commuter/distributor roads carrying 4 service buses or more per
hour between 06.00 and 10.00am, roads serving emergency
services/public transport centres/comprehensive and secondary
schools/higher education establishments, roads with gradients
greater than 10% and carrying more than 1000v/day and main access
roads to rural communities/villages. Third party funded public
highways are also treated, however this will only continue for the
duration of the external funding being made available. These will
be as identified on the Winter Gritting Route Plans;
Other Carriageways
it is Not considered practical because of
resources and costs to pre-treat all highways and other
carriageways will not be pre-treated. The aim is that these will
only be post-treated to remove ice or snow only after all the
Priority 1 and 2 routes are treated and open to traffic and when
snow or ice is likely to persist for a continuous period of 24
hours. This will also depend upon available resources.
Whenever snow is forecast we aim to pre-salt all the priority 1
and priority 2 routes prior to it falling. However this is not
always possible, for example when it starts as rain and turns to
snow. When this occurs salting is delayed until the rain stops in
order to prevent the salt from being washed away. This situation
can be even more difficult if it occurs during the rush hour as
traffic congestion impedes the gritters progress.
Once snow has fallen we will continue to work around the clock
until all roads are clear. Priority 1 and 2 roads will be cleared
first, followed by all other roads, although we sometimes have to
return to the priority 1 and 2 roads before all the other roads are
clear, to ensure they remain clear of ice and snow. This will often
be necessary towards the end of the day, especially when the snow
has been thawing all day and evening temperatures fall below
freezing causing the melt water to freeze.
During periods of snow we deploy our fleet of 16 gritters. We
also have a network of farmers that we can call on to help clear
the roads. However, salt will not instantaneously remove snow
or ice. The action of traffic is essential for salting to be
effective by breaking down the salt granules to form a saline
solution which melts the ice.
Weather forecasting and decision making
The Meteorological Office provides
us with weather forecasts which include road surface temperature
information. The forecasts form part of our computerised Ice
Prediction System, the system is monitored 24 hours a day
throughout the winter and gives the Winter Maintenance Duty
Officers the latest weather information as well as actual road
surface temperatures and other information from various sensor
sites. This information enables the Duty Officers to make their
operational decisions. Precautionary salting is carried out when
there is a clear probability of ice or snow, in that wet road
surfaces are expected to fall to or below 0º Celsius.
The Ice Prediction System allows the Duty Officer to make a more
accurate assessment of the need for salting - this results in a
reduction of the risk of failing to salt when required but also
provides a saving in costs since the number of unnecessary road
salting is reduced.
We use rocksalt and coated rocksalt as our anti-icing materials.
Our gritting fleet spreads salt onto the highway at spread rates
between 8 and 40gm/square metre depending on road surface
conditions. 8 or 10gm/square metre is normally spread when we
expect ice, and 40gm/square metre when we are trying to clear
a build up of snow and/or ice. We need to spread salt accurately as
it comes from a non-renewable source and in high concentrations, is
environmentally unfriendly and can damage vegetation.
Salt works by turning the ice or snow surrounding each granule
into a saline solution. The action of traffic is essential for
salting to be effective by breaking down the salt granules to form
a saline solution to either prevent ice from forming or to melt
it.
Ever wondered why it's brown? Find out on our Frequently
Asked Questions page.
Cycleways are salted where they form part of the 950 kilometres
of salted roads. Footpaths alongside carriageways and other
cycleways are not treated except where frosty/icy conditions last
for several days. Footpaths and cycleways may then be treated when
we have the capacity to do it.
Salt Bins
We give careful consideration to the location and provision of
salt bins so as to ensure that the maximum benefit is likely to be
obtained. As a rule, salt bins should only be provided in
residential areas adjacent to shopping areas, part way up on hills
steeper than 1 in 10 and in other areas where both need and usage
can be demonstrated which are not included on precautionary salting
routes.
No matter how accurate the forecast, there are situations where
we cannot salt the network prior to icy conditions. Such situations
are:
- When rain is followed by rapidly clearing skies, salting will
normally start after the rain has stopped (to avoid the salt being
washed away). Sometimes temperatures may fall by as much as 5°C per
hour and the wet roads may well freeze before we have been able to
salt them.
- 'Dawn frost' occurs on dry roads, when early morning dew
develops, falls on a cold road, and freezes on impact. It is
impossible to forecast with any accuracy where and when this will
occur.
- Rush hour snowfall. When rain turns to snow coinciding with the
rush hour, early salting cannot take place as it would be washed
away and gritters cannot make progress due to traffic
congestion.
We will, however, always carry out salting to remove ice. This
is not ideal and salt takes longer to act once ice has formed.
Avoid harsh steering, keep your speed down and beware of
vulnerable road users such as pedestrians and cyclists
Please slow down before you
turn. Roads bend, and so do cars!
For further information please
contact Highways Service - telephone 0300 123 7036