Winter driving tips - snow & ice
Winter conditions can be unpredictable, however most of the techniques required in cold environments are common sense.
Rules of thumb
- Keep speed as low as practically possible
- Increase the distance between cars
- Slow right down for corners, junctions and any other hazards
- If travelling long distances, be aware of changing conditions along your route
- Get all of your braking done on the straights, never brake during a corner if it can be avoided
- Be prepared for understeer and oversteer, and know how to correct when necessary
- Be prepared to use ABS or avoidance braking techniques
- Top up washer fluids and antifreeze
- Select 'snow' mode if available on automatic transmissions, or if an advanced electronic stability control system is fitted
- If you have to climb a slippery hill, ensure the top is clear before starting the ascent
Many websites have published information which deal with the above issues well, so if you need more of the basics, try a Google search. This article discusses some more advanced safety-based techniques for making progress in winter driving conditions.
Introduction to winter driving techniques
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 many automatic stability control systems which can control these actions to a limited extent, however there is no substitute for the correct technique.
Investing in a vehicle with ABS is the single most effective method of increasing your safety in slippery conditions, and luckily most modern cars have this as standard. Traction control systems can control wheelspin, but bear in mind that these technologies are reactive, which means you will already be in a certain amount of trouble before they start to operate. It's much better to avoid the problems to start with, and this is where technique comes in.
Top tips for driving on snow and ice
Pull away and accelerate gently and progressively.
In slippery conditions such as snow and ice, aggressive acceleration is likely to break traction at the driven wheels. The resulting wheelspin can lead to loss of steering control in a front wheel drive (FWD) car, or an oversteer slide in a rear wheel drive (RWD). Both of these situations will prevent you from going in the direction you want and can be difficult to recover from.
Recover from wheelspin
If you do notice wheelspin or the traction control systems fighting for grip, fight the urge to floor the throttle, and instead back off the gas and then reapply smoothly.
keep the engine speed (rpm) as low as possible
Keep a constant low throttle in order to maximise grip. Most diesel engines will cruise along happily in low gears without using any throttle as all.
Reduce torque at the wheels
Change up sooner rather than later, pull away in second gear if possible, and use the highest practical gear at all times. Higher gears reduce torque at the driven wheels and therefore lower the chances of wheelspin – especially important if you need to climb a slippery hill. Keep gear changes as smooth as possible, as it will be easy to spin the wheels in most gears when conditions are really challenging. If you drive an auto, make use of any winter settings at your disposal.
Avoid sudden driver inputs
These can include steering, braking, acceleration or gear changes. You only have a finite level of grip available so try not to overload your tyres unnecessarily. Driving smoothly will conserve grip, and make you safer on the roads.
Brake soon, and gently
If you do not have ABS fitted, be prepared to ease off the brakes when necessary to steer more effectively. Locked front wheels cannot steer!
Make the best use of ABS
If you do have ABS, you'll be able to tell it has triggered by feeling a pulsing sensation through the brake pedal. If this has occurred do not 'pump' the brakes, rather keep a firm pressure on the pedal for maximum effectiveness. ABS is designed to help you steer as you're slowing down so use this to your advantage and avoid obstacles.
Prevention is better than cure
Even if you do have ABS or traction control systems fitted, don't get into the habit of using the technology routinely, you'll be able to slow down in a shorter distance if you use threshold braking techniques.
recovering from slides in very slippery conditions
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 ahead (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).
If you do find yourself in an understeer or oversteer situation on a very slippery road try not stamp on the brakes in panic as this will make things worse. Ease off the throttle and keep the steering pointing in the direction of intended travel.
You also need to try and get the driven wheels turning at road speed to regain maximum traction. Press the clutch or flick an automatic into neutral to remove the influence of the engine and help get the wheels rotating at a more natural rate. With luck, this will create vital grip to avoid obstacles and allow you to progressively apply the brakes.
When traction is regained, be prepared to take off the steering lock quickly in order to prevent another slide in the opposite direction. Now apply the brakes smoothly and work out what to do next.
- During winter it's important to make sure you are adequately insured, especially when on a motorbike. To learn more, visit the Carole Nash Insurance Company.
Cars with electronic stability controls fitted
Most modern cars are fitted with electronic stability control systems which can be very helpful in slippery conditions. These technologies all work in roughly the same way and have two main methods of intervention:
- Reducing throttle
- Applying brake force to individual wheels
The quality of these systems do vary, but most can react very quickly and apply more precise corrections than most drivers can manage. Once stability control is activated, all the driver really needs to do is keep the steering pointing in the intended direction of travel and apply the brake when needed.
The only time you may want to think about turning these systems off is when the car is struggling to travel in deep snow, or as a last ditch attempt to pull away in extremely slippery conditions.
Stopping distances in varying winter conditions
Finally, we'll take a look at stopping distances to emphasise how important it is to slow down and brake early. Graph 1 shows the dramatic difference in braking distance when on black ice compared to normal tarmac conditions with the same tyre, it's well worth bearing this in mind in the winter an adjust your driving style accordingly.
Source: http://www.csgnetwork.com/stopdistcalc.html
Friction levels in different winter conditions
Graph 2 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.
Source: John E Hunter (1998)
Society of Accident Reconstructionists
Winter tyres
Depending on the severity of the conditions, it may be worth considering specialist winter tyres. The difference they make is remarkable. 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). The diagram below shows the effect of different rubber compounds on the stopping distances in different temperatures.
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. Thirdly, the tread tends to be wider and deeper which provides more bite when driving in the snow or on ice.
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.
Winter tyre performance
WHATCAR? magazine tested a selection of winter tyres braking from 25mph to a complete stop in a VW Golf in 2012. The results, which are dramatic, are shown below.
Driving in snow
Source: http://www.whatcar.com/car-news/winter-tyres-tested/snow-and-ice/259257
Driving on ice
Source: http://www.whatcar.com/car-news/winter-tyres-tested/snow-and-ice/259257
Snow chains
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.
Please take care on the roads this winter, and feel free to read our other winter driving tips below.
