The Science Behind Winter Driving

Car driving on wintry roadCar driving on wintry road

Have you ever wondered why black ice forms, how snow tires work or what causes hydroplaning? Let’s take a look at the science behind some common winter driving conditions in order to better understand what leads to dangerous driving situations, and help us all prepare to travel more safely this winter.

What Is Black Ice?

Black ice is not actually black in color — it’s clear enough that you can see the road beneath it, making it appear “black.” Black ice may also be difficult to distinguish from a wet roadway and may appear wet and shiny.1 An absence of air bubbles allows it to blend in with any surface, making it difficult to see for pedestrians on sidewalks as well as for drivers on winter roads. Fog, light freezing rain, and melting and refreezing precipitation can all cause black ice to form.

Even if the air temperature is above freezing, cooler surface temperatures may mean black ice could still present a hazard on the roads. Vehicle exhaust moisture can also cause black ice to form on roadways, where drivers may not expect it, such as intersections where stopped vehicles may idle for brief periods of time allowing condensate to form. If you are driving in conditions in which black ice is possible, slow down, increase your following distance and know the local weather forecast. If slick road conditions are a possibility, then consider waiting until conditions improve.

To learn more about safe driving in wintry driving conditions, check out our winter driving safety tips.

How Does Traction Control Work?

Slippery surfaces can be dangerous for drivers, with reduced friction between road and tires sometimes leading to instability, difficulty steering and spinning wheels. Traction control technology, now a standard feature on many newer cars, can help your wheels gain traction on wet, snowy and icy roads.

Unlike the anti-lock braking system (ABS), which is designed to activate when reducing your speed, traction control can help you maintain control while accelerating, driving up an incline or even at steady speeds. When sensors determine that a wheel is spinning, the traction control software can either reduce power or apply the brakes to that wheel in an effort to regain traction. Traction control and anti-lock brakes are components of an electronic stability control (ESC) system, which can help detect when a skid is about to occur, and selectively apply brakes to different wheels to help you maintain control of your vehicle. Cars with anti-lock braking systems and traction control do not necessarily have an electronic stability control system, so check on your own vehicle to determine if you have this capability.

To learn more about safe driving in winter weather, read about driving in icy conditions.

What Causes Hydroplaning?

Hydroplaning occurs when tires ride above the road surface on a thin layer of water, reducing traction. Speed, the amount of water on the roadway, tire tread depth, tire air pressure and road surface characteristics are all factors that influence whether a vehicle is at risk of hydroplaning. It is possible for vehicles to hydroplane at speeds as low as 30 mph.

To reduce your risk of hydroplaning, avoid driving through standing water on roadways and slow down to help your tires channel water through their treads to improve traction. Watch for drivers of smaller, lighter vehicles which may be more likely to lose control of their vehicles. In addition, during times of limited visibility such as heavy rain, remember to turn your headlights on to help other drivers see you. One the most dangerous times to drive is right after it starts raining, as oils on the road can rise to the surface and contribute to slick conditions.

To learn more about driving in heavy rain and wind, check out our safety tips.

How Do Snow Tires Work?

Swapping out your “all season” tires for snow tires during the winter months may afford you better traction and performance in snowy, icy and slippery conditions. That’s because there is real science behind the design of snow tires: they’re made of a softer rubber compound that will not stiffen when temperatures drop as much as all-season tires will. While it’s less durable and subject to greater wear than the stiffer all season compounds, the softer rubber compound in snow tires helps to retain tire flexibility in cold weather, an important attribute for improving traction on slippery surfaces and helping drivers stay on the road. The addition of “sipes,” or grooves, on snow tires is designed to provide more “leading edges” on each tread block and this helps to increase traction on slippery road surfaces.

Learn more about whether you might need snow tires during the winter months.

As winter rolls in, there is a growing possibility of finding yourself driving in less than optimum conditions. Understanding the science behind some of these common conditions can help heighten your awareness to stay safe on the roads.