Dangers of Driving in Winter Conditions

Winter driving conditions challenge most drivers, but Security Drivers are not in the “most drivers” club. Other drivers may have the option not to drive in winter weather conditions, but not driving in icy and snowy conditions is a luxury that most security drivers don’t have. 

An interesting metric from our (ISDA) Executive Vehicle & Secure Transportation Survey is – Seventy percent of survey participants drive in winter conditions—this number aligns with the national (U.S.) average.

These facts and statistics support the dangers of driving in a winter environment.

  • 17% of all vehicle crashes occur during winter conditions. There are about 156,000 crashes annually due to icy roads. 
  • Weather-related vehicle accidents kill more people annually than large-scale weather disasters. 
  • It takes up to 10 times longer to stop on snow and ice than on dry pavement.

The Winter Version of the Security Driver Triangle

Any form of driving, including winter driving, is a balance. For decades we have referred to that balance as the Security Driver Triangle. The triangle comprises three components: THE DRIVER, THE MACHINE, and THE ENVIRONMENT.

When measuring driver capability, you cannot separate the vehicle from the driver; both contribute, along with the environment, to the driver and the principal’s safety and security.

Skilled security drivers understand environmental changes that affect vehicle driver combinations. They anticipate changes in behavior and are ready to maximize the vehicle’s capability. Driving in winter conditions significantly decreases the vehicle’s capability. The security driver understands various vehicles’ characteristics and limitations, including All Wheel Drive (AWD).

There is a misconception about the capability of AWD and FWD in winter driving conditions.

A quick definition of AWD and FWD

All-wheel drive refers to automatic four-wheel-drive systems where the vehicle selects two- or four-wheel drive based on road conditions. Power gets directed to individual wheels with the best traction in slippery conditions. Forgetting out of snowed-in parking spots or tackling unplowed roads, AWD does little to aid turning and braking on snow and ice.

That’s not to say that AWD is not helpful in bad weather. It might be enough to get the vehicle up snow-covered hills and move it from a stop position where 2WD would not accomplish that.

The problem is that most 4WD/AWD drivers think they have a vehicle that can defy the laws of physics. No matter what vehicle the security driver is in, stopping on snow and ice will require up to 10 times the distance as stopping in normal conditions, and driving onto an off-ramp during black ice or wintry conditions will require a lot less speed than usual. The driver must anticipate that lower speed before getting to the off-ramp.

The Science of Winter Driving

If you are an ISDA-certified driver or attended an old Scotti School or Vehicle Dynamics Institute training program, you are trained and measured to use 80% of the vehicle’s capability to avoid or escape an emergency. That means the driver can apply 80% of the vehicle’s weight, pushing on the vehicle’s center of gravity in a braking or turning scenario or a combination of braking and turning. In winter driving conditions, the key phrase is “vehicle capability.” 

When driving from dry conditions to snow or ice, the traction to maneuver your vehicle (the vehicle capability) has decreased by 65%, so you suddenly have gone from an 80% driver to a 15% driver. This means you can only use 15% of the car’s capability to stop and turn, which is unpleasant.

Imagine that you cannot drive at a speed greater than 20 MPH without losing control; that is the difference between driving on ice and the pavement.

If the coefficient of friction between the tire and the road surface is low, you only have two options: decrease your speed and limit your steering. But, since you may have to use the steering to drive onto an off-ramp, your only real option is to lower your speed.  

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Summary

No 4WD or AWD system will compensate for the 65% decrease in traction. The less adhesion between the tire and the road, the lower the vehicle’s capability.

But using some simple math, consider that when you were driving on icy roads, the coefficient of friction is very low, so having the capability to use 80% doesn’t mean much because 80% of .1 is still a dangerous scenario.

Stopping on snow and ice may require up to 10 times more distance than in normal conditions. 

You can’t beat the laws of physics, so the only way you can survive driving in these conditions is to keep the speeds down. 

Using caution when driving in winter conditions can help keep yourselves and your clients safe on the roads. Stay safe, and drive carefully.

Additional Tips

Here are a few additional tips to help you stay safe on the roads this winter:

  • Slow down and leave extra space between you and other vehicles. It takes longer to stop or maneuver on slippery roads.
  • Keep your vehicle well-maintained, including regular checks on your tires, brakes, and windshield wipers.
  • Always clear snow and ice from your vehicle’s windows, mirrors, and lights before you drive.
  • Use your headlights when visibility is low, and don’t use high beams on snow-covered roads.
  • Avoid sudden movements, such as rapid acceleration or braking, as they can cause your vehicle to lose traction.
  • Be aware of black ice, a thin and almost transparent layer that can be hard to detect on the road.
  • Keep an emergency kit in your vehicle, including a blanket, food, and water, in case of a breakdown or unexpected stop.

References and Resources

Winter Weather Driving Tips

Episode 196 – Science of Winter Driving

Episode 159 – Cold Weather and Tire Pressure

Driving in Winter Weather

Cold Weather and Tire Pressure

What Does Cold Weather Do To Your Car? This Chart Will Show You