
Winter conditions can be unpredictable, however most of the techniques which are required in cold environments are pretty much common sense:
Many sites have already published which deal with the above issues well, so if you need more information, try a Google search. This article discusses some of the more advanced safety based driving techniques for winter driving.
Icy roads provide significantly lower levels of grip than dry tarmac, so making the most of available traction is key to winter driving. Loss of traction can lead to wheelspin under acceleration, wheel lock under braking and sideways sliding while cornering. There are now many computer controlled systems which can control these actions to a limited extent, however there is no substitute for careful driving. Investing in a vehicle with ABS is the single most effective method of increasing your safety in slippery conditions. Traction control will control wheelspin to a limited extent, but bear in mind that such systems are reactive, which means you'll have to be in a certain amount of trouble before they will start to operate. Much better to avoid the problems to start with.
Note: If you're an experienced driver you may be able to use other techniques to help recover from these situations, and these are covered in the dedicated oversteer and understeer articles.
Understeer is when you turn the steering wheel but find that the car has a tendency to continue straight on (Figure 1). Oversteer is when the car tries to spin round due to a lack of traction at the rear (Figure 2). Both situations are more likely on winter roads but can be helped using the same techniques (which should make things easier to remember).
Figure 1: Understeer - the car continues straight on despite applying steering lock

Figure 2: Oversteer - the rear of the car breaks loose and a spin is likely if not corrected

If you do find yourself in an understeer or oversteer situation do not stamp on the brakes in panic as this will make things much worse. First you need to try and get the driven wheels turning at road speed and regain some traction. Pressing the clutch or flicking an automatic into neutral will remove the influence of the engine and help get the wheels rotating at a more natural rate. Hopefully this will create vital grip for avoiding obstacles and allow you to progressively apply the brakes. Point the steering in the direction of intended travel, but don't use excessive steering lock, if a car starts to understeer many people will panic and apply as much steering lock as they can, but this can make the car less likely to make the turn. When traction is regained, be prepared to take off the steering lock quickly in order to prevent another slide.
If you're car is fitted with electronic stability control systems such as DSC, ESP or other related acronyms the car can takes some of the control back from the driver by reducing throttle and braking individual wheels where necessary. In this case ensure the system is turned on (usually on by default) and make sure your steering is pointing in the intended direction - the car will do the rest. Modern traction and stability control systems will automatically make the best possible use of available grip and help you avoid an accident. If in doubt, gently use the brakes to slow to a halt.
Depending on the severity of the conditions, it may be worth considering specialist winter tyres. These vary from a Mud and Snow (M&S) rating through to studded tyres for icy roads. Surprisingly, with the correct tyres fitted, driving in quite severe conditions can become remarkably easy – you just have to pay a visit to Finland or other northern countries in the Winter for a demonstration.
Manufacturers of winter tyres use several methods to increase friction and help maximize control. Firstly, the rubber compounds are usually softer which allows optimum friction to be reached at lower temperatures (this however does make them wear faster when used in warmer conditions on dry tarmac). Secondly, winter tyres can have small 'sipes' which are formed into the rubber within a tread block - these provide grippy edges which are especially useful when driving in snow.
Sipes: the horizontal lines shown in the image below. These provide grippy edges which help when driving in snow.

Winter tyres usually also have an aggressive block-like tread pattern which can help to dig into the snow and provide traction (also useful in muddy conditions). Finally, small studs can be fitted to the tyre and these provide a great deal of benefit when driving in icy conditions, although in some countries these are only permitted in the coldest months as they damage road surfaces. Studded tyres can also increase your braking distance when on a clear dry road.
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If you're driving in deeper snow, it might be worth considering using snow chains, or at least having some in stored in your car. These are fitted to the driven wheels and can provide dramatic increases in traction. If you do choose to fit snow chains, ensure the manufacturer's instructions are followed carefully or damage to your car could result.
Graph 1 shows the dramatic difference in braking distance when on black ice compared to normal tarmac conditions, it's well worth bearing this in mind in the winter an adjust your driving style accordingly.
Graph 1: Stopping distance vs speed for dry asphalt and black ice

Source: http://www.csgnetwork.com/stopdistcalc.html
The table below summarises the levels of friction available in different winter conditions - the worst conditions observed provided only approximately a quarter of the grip of dry asphalt.
Table 1: Grip levels in different conditions (calculated as the coefficient of friction)
| Classification | Description | Grip available (coefficient of friction) |
| Dry Asphalt | This value is commonly used as the reference value for rubber tyres on dry asphalt. Concrete is typically lower. | 0.68 to 0.85 Average value of 0.72 |
| Partial Frost | Light or partial coating of frost on the road surface. Visible to the driver as intermittent frosting appearance. | Partial Frost had
a resistance level similar to the lower range of wet
asphalt. Average value of 0.63 |
| Frost | General white coating covering entire lane. Visible to the driver and completely recognizable as frost. | Frost was .10 less
than Partial Frost. Average value of 0.53. |
| Heavy Frost | Almost ice conditions. Heavy white coating and very visible to the driver | Heavy Frost had a
value close to the higher ranges of ice. Average of a 0.39. |
| Tracked Snow | Snow compacted by vehicles. | The test results
varied in range. Average was a 0.35 |
| Untracked Snow | Snow not compacted by prior vehicles. | The individual
readings were similar to Tracked Snow. Average of 0.35 |
| Snow & Ice | Generally known by motorists as compact snow and ice, or 'hard pack'. | Snow and Ice was
nearly identical to the frictional resistance found for
Black Ice, 0.25 to a high of 0.41 Average of 0.32 |
| Black Ice | Icy layer generally covering asphalt, difficult to see by the average driver. Often found on overpasses and elevated structures. | The ranges for
Black Ice varied from a low of 0.25 to a high of 0.41 Average of 0.32 |
| Sunny Ice | Ice that has been exposed to the heating rays of the sun. A water layer was not generally observed. | Sunny Ice yielded
low readings, Average of 0.24. |
| Wet Ice | Ice covered with a layer of water. Generally seen when the temperatures are around zero degrees Celsius. | Wet Ice, similar
to sunny ice, Average of 0.24. |
| Glare Ice | Ice that was the smoothest surface observed. Similar to wet ice except the water layer was not observed. | The lowest value
measured was Glare Ice. Average of 0.19. |
For even more winter driving tips, please see our blog article here