Last reviewed 31 December 2021
For much of the UK in recent years, winter road conditions have been generally benign. Although certain parts of the country are still liable to snow and ice, these conditions may strike anywhere and the fact they are less frequently encountered means many drivers have little experience of dealing with them. High winds, fog and heavy rain are also likely to occur at any time of year.
The principles of driving in adverse conditions are essentially the same as for any other driving, although certain things may become more important. The key elements of defensive driving remain, as always, preparation, observation and anticipation. This article looks at these aspects with respect to adverse weather conditions.
Preparation before driving
Some fundamental aspects must be covered before the engine is even started. This is always the case and concerns three main elements: the vehicle, the driver and the route.
As far as the vehicle is concerned the standard daily walk-round checks will cover most things but there are one or two special points to cover.
Windows and mirrors should always be clean and completely unobscured and in winter this also applies to snow and ice. Clearing a hole to look through is not enough, the whole area of glass must be cleared or an offence will be committed. Snow that builds up on top of any vehicle must also be cleared before driving, as it may well blow off onto a following vehicle and cause an accident. Driving with a heavy snow build up on a vehicle can also be a prosecutable offence.
It will always be good practice to make sure the fuel tank is full before leaving the depot and that will be especially important in winter conditions so that the heater can be operated in case of a prolonged stop. Additional equipment such as snow chains should also be carried where they are required by local laws. One thing to remember is that headlights that switch themselves on automatically when light levels fall may well not react in daylight conditions to fog, rain or snow. It is therefore up to the driver to ensure that headlights are on when visibility is seriously reduced (less than 100m) during daytime.
In snow, when stopped for a break, the vehicle should be checked before setting off again to ensure that there has been no significant build-up of snow that may blow off or ice that may prevent the full range of operation of controls and windscreen wipers. Large goods vehicles will have a large clearance between the tyres and the wheel arches but smaller vehicles should certainly be checked after driving some distance in snow to see that there is no build-up of packed snow around the wheel arches that may restrict steering lock.
There are also some extra factors that need to be considered for the driver. Climate controlled cabs are all very well and drivers can get away with wearing just a t-shirt in all weathers but in case of a breakdown, a long, enforced halt, or even the need to leave the vehicle, some warm clothing and substantial footwear should at least be carried on any journey. Wet weather gear is advisable at any time of year. Driver preparation should also extend to having some food and drink (preferably hot) in the cab when on longer-distance runs.
Selection of the route becomes even more important when there are adverse weather conditions. When high winds and/or heavy snow are likely, routes over high ground, and even those over lower ground with long exposed sections, should be avoided wherever possible. Even without exceptional delays, journeys in bad weather will take longer so thought should be given to suitable stopping points for breaks and rest which may be in different places and at shorter intervals than usual.
Observation while driving
Once on the road, the usual all-round observation and scanning of the far, middle and near ground ahead will be even more important so that the driver is prepared to take any necessary action in response to adverse road conditions (see below).
Observation should extend to the likely developments in the weather and the impact on the road situation. Watching the clouds ahead and to the side from which the prevailing weather comes may give advance warning of heavy rain or snowfall affecting the road ahead and clear skies in winter, particularly at night, will indicate the likelihood of frost and icy roads.
Similarly, the nature of the road and its surroundings can also suggest where there are likely to be icy patches. For example, a road that runs under a cover of trees will generally not be so susceptible to ice as one that is exposed on one or both sides (but it is also necessary to watch out for fallen trees in high winds). Bridge decks are very likely to be icy as they are exposed not only at the sides but also from below.
Anticipation of hazards
When roads are likely to be, or are, slippery more anticipation than usual will be required. Under nearly all conditions a vehicle moving at a steady speed in a straight line will be in a stable condition but the sudden need to change speed or direction is when loss of control is most likely to happen. However, if the required degree of observation has been maintained there should be no sudden surprises and with ample warning, it should be possible to carry out all manoeuvres as slowly as necessary to avoid loss of control.
In very slippery surface conditions, braking can be avoided almost entirely if the speed is correct and the driver observes and anticipates sufficiently. Simply lifting, progressively, off the accelerator and allowing engine braking to slow the vehicle should be all that is needed.
The general rule is to always drive at a speed that will enable you to stop safely within the distance that can be seen clearly ahead and that will not only vary with bends in the road, etc but also with the general visibility, which may be greatly reduced by fog, heavy rain or snow.
An important part of anticipation is to allow sufficient distance from the vehicle in front to be able to stop safely whatever the vehicle ahead may do. The normal rule is to leave a 2-second gap, but this must be extended to 4 seconds in the wet and 10 seconds or more in snow and ice. In the worst conditions, the governing factor should be the distance judged to be necessary to stop by using engine braking without the brakes at all.
Driving tips for adverse weather
When driving on snow and ice, the basic rules of off-road driving should be followed:
drive as slowly as possible and as fast as necessary
always use progressive acceleration, gentle steering and progressive braking with no harsh movements
always use the highest possible gear and use a steady momentum to maintain forward motion
moving off in second gear will help prevent wheel spin
if the wheels start to spin, ease off the accelerator to allow them to grip again before gradually accelerating again to regain momentum.
Don’t drive onto a flooded road if the depth or length of the flood is unknown. Although a large vehicle may well have sufficient ground clearance and mass to prevent it from being drowned, there may be obstacles hidden under the water or manhole covers displaced, etc. When it is necessary to drive on a flooded road, drive in first gear in the middle of the road and maintain traffic in one direction at a time to prevent a “bow wave” that may swamp a vehicle coming in the opposite direction.
Such inconsiderate driving through flood water is an offence as is splashing pedestrians by driving too fast through puddles.