Winter Maintenance

The UK climate is unusual, being heavily influenced by a range of weather systems, many of which bring mild, wetter weather from the Atlantic on the Gulf Stream. In winter these can occasionally turn to sleet and snow, but more often than not the colder winter weather comes from the north and eastern Arctic or Baltic directions. These weather systems can bring severe, if often short lived, winter conditions to the British Road Network. To try and combat these conditions, and keep as much of the road network operating as is possible, all roads authorities have winter maintenance programmes, which include some or all of the following.

Planned Treatments

Gritting on the A632

Planned or preventative treatments, more commonly known as gritting, are carried out in advance of the onset of forecast cold weather. The majority of roads authorities have a fleet of lorries which can be adapted to be used as road Gritters, whether through the use of bespoke vehicles or demountable gritter bodies, adaptations to tipper bodies or other specially designed equipment. Gritter can come in a variety of sizes, ranging from small pick up trucks for local or narrow road treatments up to 32 Tonne, 4 axle lorries capable of treating many miles of roads before being refilled. Many of these vehicles have, in recent years, been given catchy names to make them more appealing to the general public.

In the past, these trucks applied the grit, or road salt, indiscriminately, or at the very least at the drivers discretion along selected routes. However, modern vehicles are nearly all computer controlled, and use a variety of sensors and weather data to apply the treatment in a more targeted manner. The data used includes weather forecasts, live temperature readings of both air and road surface, and how much and how recently road salt has been applied to the road. This all helps to reduce the volume of road salt being used by the roads authorities, which reduced costs, and limits any harm to the environment. The lorries have to travel at set speeds when treating, with the computers also reducing the flow of road salt when the vehicle slows down for corners or traffic. Often the maximum speed when treating is around 40mph, but with flashing orange lights and bright paintwork, these vehicles are highly visible on the road even in poor weather.

On the larger, bespoke gritter bodies, the grit is loaded into a large hopper unit mounted on the chassis, and then fed down into the 'spinner' which is mounted at the very rear of the vehicle. This is designed to allow an even spread of road salt across a standard S2 road width whilst the vehicle is travelling solely in its own lane. While this does mean that oncoming and overtaking traffic can be sprayed with road salt, it normally means that a gritter can treat the whole road in a single pass, without needing to make a return trip to treat the other lane. On 3 lane Motorways, the spinner is normally designed to allow the gritter to treat all of the lanes whilst travelling in the middle lane. It is likely that four and five lane motorways require two vehicles, however. Smaller vehicles operate in a similar way, although those which are converted for the winter season are probably a little less accurate in their spreading, and without the hopper shaped body, they are less efficient as they never completely empty the tipper body.

Adaptations to the standard designs have been tried in the past. One such adaptation was to try and direct the road salt to the front of the vehicle and treat the road in front of the gritter. This gave the benefit of allowing the weight of the gritter to press the salt into any lying snow or ice, and also therefore minimise any loss of traction experienced. However, as most modern gritters do not use this design, it seems likely that it proved unsatisfactory overall.

Grit Bins

Grit Bin in Harpenden

In addition to preventative treatments, most road authorities maintain a large number of public grit bins, particularly on steep hills, to enable the general public to apply grit to roads or pavements when the planned treatments prove insufficient. These grit bins are normally filled in the autumn, and checked throughout the winter, although in recent years some councils have asked the local communities to check the grit bins and report back via an online form when they need filling. This seems to be a cost saving measure, and undoubtedly means that there are many grit bins which are found to be empty when needed.

There are many types of grit bins in place around the country. Most of the newer ones are of plastic construction, self coloured in yellow. They have opening lids which have seals and channels to prevent water ingress and allow the grit to be readily dug out (shovels are not normally provided). However some older ones, particularly those installed by the Scottish Regional Councils between 1975 and 1996, are constructed from thin prefabricated concrete panels which slot together onsite. Some, but not all grit bins have bases, those without being sited on concrete slabs.

Snow Ploughs

A Snow Plough clearing a road at Kiltarlity in the Highlands

When a heavy blizzard dumps a lot of snow on the landscape, it is rare for the preventative treatment to be sufficient to keep the road open in itself. In order to keep the road open, snow ploughs are used, often mounted on the front of the larger gritter vehicles. These ploughs are large curved metal blades which can be adjusted hydraulically by the driver to change the angle and height from the road surface. The lower edge of the blade is a plastic or rubber strip, designed to minimise damage to the road surface, although they are normally set to plough a little above the road surface itself for the same reason. The curvature and angle of the blade are designed to push the snow away from the crown of the road and onto the verge.

Pavement plough on the A93 in Perth

On multi lane roads, such as motorways, ploughs often need to work in parallel, clearing each lane in turn from the outside to nearside so that the plough on the nearside lane is moving two or three lanes worth of snow. For more rural routes, smaller ploughs can be mounted onto tractors or other plant vehicles, some of which will also tow a gritter trailer, or have a small gritter hopper mounted on the rear PTO. Small vehicles such as these can also be used in urban areas to help clear pavements and footways.

It is rare for roads authorities to plan to completely plough roads in the first instance in severe conditions. Instead, a single lane is cleared, with some provision for vehicles to pass. Persistent heavy snowfall can build up much quicker than the authorities resources are able to plough the roads, resulting in more problems elsewhere. In these conditions, these days with multiple weather warnings and warnings not to travel unless essential, the volume of traffic on the roads is anticipated to be far lower than normal, meaning that a reduced clear road width can be sufficient until the snowfall eases and the road can be fully cleared.