Why do we get snow lanes

FARGO - Every time it snows you can see where tire tracks are on the road. But there is more going on than meets the eye.

Even without cars on the roadways, we can tell which areas see the most traffic by the snow-free lanes on the streets.

These lines after a snowfall quickly show us where tires have been pushing the snow away from underneath the wheels, especially when temperatures are mild, but we can see these lines even after snow is compacted and the temperature is too cold for salt and sand to be effective.

That’s because of frictional heating between the tires and the road. You can feel this yourself just by rubbing your hands together, the friction between the two creates heat. A quick check of the tire temperature before the car hits the road measures -11 degrees. As you drive, the frictional heating caused by accelerating, braking and turning increases the temperature of the tires. After driving around town the tire temperature is up to 27 degrees.

After a half an hour of highway driving that temperature can increase by as much as fifty degrees and some of that heat is transferred to the road. The pavement in the driving lanes can warm up three to five degrees more than the undriven pavement to the sides. This can be enough to melt some of the snow and ice in the more commonly driven lanes.

Though when the temperature stays below zero for a long time, that small increase in temperatures doesn’t make much of a difference which is why the roads are worse with a frigid forecast after a fresh fallen snow.