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Difficult driving conditions

Difficult driving conditions caused by snow, heavy rain, fog or slipperiness are challenging to drivers. Anticipatory driving is the best way to respond to these challenges of changing weather conditions. A proactive driver keeps a longer distance from those in front, plans the trip according to weather and identifies hazards in time. The right speed for the situation and sufficient safety distance from other road users also enable safe travel in poor and slippery road conditions.

Preparation for weather changes during the winter are made by activating the winter speed limits. In slippery conditions during the winter, braking distances are much longer than in summer. In addition, the dark season requires lower speeds. The current situation should always be taken into account when choosing a speed. There does not always have to be snow and ice on the road for it to be slippery. Mere asphalt wet from rain is much more slippery than dry road surfaces, and mud or leaves on the road are particularly slippery for motorcyclists and mopeds.

Winter catches drivers by surprise – once again?

The slippery conditions in autumn and winter seem to catch Finns by surprise every year. Varying road conditions also increase the risks of traffic accidents. In winter, for example, the risk of accidents is greatest at the beginning and end of the season. Stable weather conditions, be it good conditions in the summer or slipperiness in the winter, make it easier for drivers to behave in accordance with the conditions, but in sudden weather changes, the driver’s behaviour does not change sufficiently. Studies show that the rarer the weather, the higher the accident risk.

Advance information can also be obtained about any challenging weather to be expected, and checking the weather forecast for the next day is a recommended habit. When bad weather conditions are likely, you can reserve more time for your journey, replan the route, change the mode of travel or postpone your journey to wait for better weather.

Taking the weather into account with the correct speed and safe distance

In poor driving conditions, you can allow for more surprises caused by the weather by maintaining a proper safety distance and regulating the speed sensibly. Too short a distance from the driver ahead often leads to rear-end collisions. Many disastrous collisions with incoming traffic also originate from short distances. 

In high-traction weather conditions, the driver is forgiven many of their mistakes, while on a slippery road, the driver’s incorrect assessments result in immediate consequences. In slippery weather conditions, braking distances will increase considerably, and even good winter tyres will not produce the traction of summer weather.

If you drive at 80 km/h on a dry asphalt road, you need almost 50 m and about four seconds to stop. On a snowy road, stopping from a speed of 80 km/h requires a distance of almost 50 m more and about four seconds more than in summer. These seconds can be fatal. You can stop in the same distance as in summer only if your speed is 60 km/h or less.

Black ice and aquaplaning

A road is at its most slippery at an ambient temperature close to zero. Traction may vary greatly over just a short distance. If a moist and cloudy evening or night is followed by a cold and sunny morning, the air cools quickly and a thin and a transparent ice film called black ice can quickly form on the surface of the road. Sometimes black ice can also form in freezing temperatures when the road surface is heated, on which the momentarily thawed water quickly refreezes due to the icy surface.

Compared to other ice types, black ice is exceptionally slippery and difficult to detect. Black ice is often also found on bridges, where the air moving above and below the structure causes the temperature to change rapidly.

If there is a lot of water on the road, a tyre may lift off the road over a plane of water. In aquaplaning, the vehicle cannot be steered, because the tyres are no longer in contact with the road. If there is slush on the road, the car may also start slush-planing, even more so than aquaplaning during rainfall.

The best way to avoid loss of control is to reduce your speed and avoid driving in tracks. If you start aquaplaning or slush-planing, press the clutch fully down and allow the speed to decrease. Avoid strong steering movements.

In the autumn, in addition to rainfall, the surface of the road may be made slippery by leaves falling from trees and by mud. Moped and motorcycle riders in particular should take this into account.

How to maintain traction in slippery conditions

On a slippery road, it is worth remembering that the tyres will not lose their traction by themselves. The loss of traction is caused by the driver’s actions. To prevent loss of traction, try to:

  • Start and accelerate so that the driving wheels are not spinning.
  • Drive into curves at moderate speeds to prevent the vehicle sliding sideways.
  • Avoid driving at high speed through snowdrifts, water-filled tracks or puddles.
  • If you drive with an older vehicle without ABS, avoid lock-braking. If the wheels are locked, the vehicle cannot be steered, but it will move according to the gradient of the road and, in the worst case scenario, may end up in the incoming lane.
  • Avoid strong steering movements.
  • It is a good idea to avoid overtaking in bad weather. Careless overtaking in slippery conditions may result in loss of control of the vehicle, which in most cases occurs when the driver returns to their lane after overtaking.

Winter tyres

Winter tyres must be used from the beginning of November to the end of March, as long as weather conditions so require. Winter tyres can be either studded or non-studded. Non-studded winter tyres, so-called friction tyres, may be used all year round. However, for example, the Tyre Specialists of Finland (Opens in a new window) does not recommend friction tyres for year-round use due to their poor wet grip properties. Read more about winter tyres.

Visibility and observation

When driving in rain, fog, low light or dark, the hazards are the same as when driving in bright conditions. As much light as possible is needed on the road to observe them. Even efficient use of lights does not guarantee daytime visibility. It is therefore necessary to reduce the speed. Even a slight change allows for more time to react to surprises.

The high beam must be used whenever possible without glaring others. Focus your gaze at the extreme limits of the headlights. When encountering incoming traffic, you should look further away to the right side of the road and to avoid dazzling.

When encountering incoming traffic with low beam headlights, you can only see approximately 30 m away. At a speed of 100 km/h, this will take about one second. Not much can be done in that time.

To ensure visibility, it is advisable to clean the front and rear lights regularly, especially in muddy or snowy conditions. In addition to the outer surface, the windscreen should also be cleaned regularly from the inside. A dirty inner surface of the windscreen causes glare due to the bending of the light, especially for light coming at an angle.

The vehicle must not be left unlit in the road area.

Always have a reflector with you in the car, and dress warmly

Motorists know how hard it is to see a pedestrian without a reflector, even if the road is illuminated. Many people travelling by car feel that a reflector is not needed, but drivers also become pedestrians when they get out of the car. Reflectors are especially needed if the vehicle breaks down or assistance is needed in the dark.

It is not always self-evident that the journey will be comfortable in a warm car – either as a driver or as a passenger. When taking a car journey in the winter, it is important to dress warmly or at least bring the equipment suitable for outdoor conditions.

For the safety of those in the car, it is advisable to keep in the car or in the boot

  • warm clothes,
  • reflective vests or reflectors – the reflective vest is a better option, as it makes people getting out of the car visible to other passing traffic even in bright conditions, and
  • a flashlight. 

Winter speed limits

Speed limits are reduced on main roads for winter months. They are intended to improve road safety due to slippery road surfaces and dark time.

Many people feel that the start date of the speed limits for winter and dark time is early, as winter conditions, especially in southern Finland, can usually only be expected far into December.

Winter speeds are not only about slippery road surfaces, but also about speed limits in the dark. The aim of reducing speeds is to reduce the risk of accidents due to seasonal fluctuations.

Winter limits save lives

It has been estimated that the speed limits for winter and dark times save eight lives every year and keep another 36 people from getting injured. In the case of colliding with a deer, elk or reindeer, the greatest risk is in September–December, and the increase in speed significantly increases the risk of death or serious injury. Two thirds of the accidents resulting in personal injury occur during low-light or dark conditions, and 40% of them occur in an area with a speed limit of 100 km/h.

The speed limits for winter and dark time will be changed in October and November due to darkness and slippery night conditions. However, the weather conditions are monitored and changes are made accordingly. The restrictions are imposed before the snow arrives, because of the dark. After the winter has come, the main reason is slipperiness.

Remember also the safe distance

In poor driving conditions, you can allow for more surprises caused by the weather by maintaining a proper safety distance and regulating the speed sensibly. Too short a distance from the driver ahead often leads to rear-end collisions. Many disastrous collisions with incoming traffic also originate from short distances. 

In high-traction weather conditions, the driver is forgiven many of their mistakes, while on a slippery road, the driver’s incorrect assessments result in immediate consequences. In slippery weather conditions, braking distances will increase considerably, and even good winter tyres will not produce the traction of summer weather.

If you drive at 80 km/h on a dry asphalt road, you need almost 50 m and about four seconds to stop. On a snowy road, stopping from a speed of 80 km/h requires a distance of almost 50 m more and about four seconds more than in summer. These seconds can be fatal. You can stop in the same distance as in summer only if your speed is 60 km/h or less.