What Makes Ice so Bad for Driving?

            If you live in a place that gets hit with generally cold weather, and develops icy roads, then you know exactly how dangerous driving on the ice can be. There are a few key things that you must keep your eye on when driving in conditions that may have ice build up on the roads. The first is simply ice, where you can see it and feel it. The second is something much scarier and more dangerous, called black ice, that you cannot see because it is completely transparent with the pavement below. There are a few things that change when you are driving on ice. For the most part, they are obvious, however, they may not be so obvious until after it is too late.


            All tires and materials have some sort of coefficient of friction that occurs between them and the material they are coming in contact with. According to a PDF from West Virginia University, the coefficient of static friction between rubber (car tires) and asphalt is between 0.5 and 0.9. This is why generally, cars get very good traction in dry and ideal conditions. However, driving in conditions that cause ice build up and black ice to form are a completely different story. If you are in bad enough conditions that are close to, or below, 32 degrees Fahrenheit, the coefficient of static friction of your tires could go down to almost zero, which would mean that your tires no longer any traction on the slippery roads. According to a lecture given by  Dick Heckathorn, during conditions such as the ones described, the coefficient of static friction between rubber and ice can be as low as .005, which is a great deal lower than between rubber and dry asphalt.

            Now, you can add this in to what was talked about earlier in the chapter, with the force of going around a turn, and you can see that with an extremely low coefficient of friction, it would be very easy for the centrifugal force to overcome to force between the tires and ice, making ice extremely difficult to drive on. Ice, because it has such a low coefficient of friction makes driving much more dangerous because the force of the contact between your car tires is significantly reduces from that of tires and dry road.