How weather indexes affect road traffic strategy

How weather indexes affect road traffic strategy

Posted on 20 Sep 2017

One of the strongest reasons to check the weather forecast is road traffic safety.
Unfortunately, any weather change leads to an increasing number of road traffic crashes. However contrary to popular belief, one of the main reasons behind traffic collisions is neither sudden snow fall nor unexpected rain, but driver’s lack of knowledge about the weather influence on road traffic safety on the whole. And consequently, a significant part of drivers do not pay proper attention to a current weather forecast and they choose an inappropriate for the present weather way of driving. For example, many drivers comply with road speed limits only when the weather is really nasty, and such measures as usage of fog lights and reduction of cases when a driver changes a lane are rarely used. Nevertheless, even a light rain or haze can lead to increasing braking distance of a vehicle and trigger an accident.  

And what is particularly bad, the aggravating weather conditions enlarge an amount of cases when pedestrians are involved in traffic collisions. A driver does not plan to be a killer, but sadly such accidents happen often nowadays. Statistics say that in town areas every tenth crash is a collision of a vehicle with pedestrian.

Let’s consider how weather indexes affect road traffic strategy

Temperature, cloud cover  

Influence of heat on human body is similar with alcohol effect: cognitive function becomes deficient and reaction time in an extraordinary situation increases. High temperatures have a relaxing action on a human body, vigilance is dulled, and heat provokes exacerbation of various chronic diseases, severe headaches and general deterioration of well-being.

Along with that, a vapor film is formed on a sun heated road and thus friction of a car with a road is sharply decreased. It means the increased braking distance.

Bright sun blinds a driver and gives dazzles on asphalt.

Visibility is low when it’s foggy, and distance to objects seems bigger than it is really is. And also perception of colors, except red, is changed. For instance, yellow appears reddish, green as yellowish. Fluctuation of temperature near zero causes water freezing or ice melting and it also changes friction of a car with a road. Frost brings icing of windshields and side mirrors.  


Downpour and rain give rise to the following dangerous conditions: downgrading visibility, friction reduction; water reaching brake pads reacts as a lubricant and highly decreases brake efficiency performance.

Icy rain causes icing of the road surface and thus friction is reduced to almost zero.

Sudden snow fall leads to poor overlook and also friction reduction.

Wet snowing brings little visibility, and friction reduction takes its toll on heavy-duty vehicles down the slopes.    


Stormy wind produces lateral force on a car and as a result a sudden change of a trajectory happens with some objects inside a car being scattered near a windshield which creates disorientation for a driver.

Atmospheric pressure

This factor can strongly influence driver’s well-being and lead to the loss of concentration. Reduction in atmospheric pressure is especially sharp and painfully perceived by people who have high intracranial pressure. Such people suffer from migraine attacks at those moments. With an increase in atmospheric pressure well-being of hypertensive patients, patients with bronchial asthma and allergy becomes worse.

In the days of magnetic storms, there is a sharp increase in possibility of hypertensive crises, heart attacks and strokes. And such person quite can be at this time behind the wheel.

The negative role of weather phenomena in traffic accidents has been taken into consideration by insurance companies and car manufacturers some time ago. Presence of convenient weather API lets take various measures in such cases.

Precautionary measures: weather monitoring and alerting system which provides customer notifications about extreme weather phenomena in customer regions, so as customers are warned to take necessary safeguard measures.    

Supervisory measures: major car manufacturers can collect data about the driver behavior on the road in different weather conditions. Evaluation of adequacy of the driver behavior influences a following disbursed insurance amount, and such approach is actively introduced. For many car owners this practice is significant stimulus to pay more attention to weather situation when planning a car ride.