As we slowly start the annual transition to spring, the daylight hours lengthen, and the sun moves higher in the sky, giving more direct sunlight, warming everything it touches. But there is a very dangerous downside to this change of seasons. As the ground warms, the black pavement warms faster, bringing the frost out of the ground. This creates 2 very hazardous driving conditions: The most dangerous is frost covered roads. It’s almost impossible to see, far more difficult to see than black ice, but just as dangerous. Fortunately, it is only a serious danger from about 30 minutes before sunrise, to about 30 minutes after sunrise. The other danger is road damage. As the frost comes to the surface, it causes the road to heave upwards, and creates small air pockets under the road surface. As trucks drive across them, the weight can pop these bubbles, similar to the way you can pop bubble wrap, with the same effect. Except it’s the road surface that breaks to allow the air to escape. These small holes in the road surface will fill with water, which will freeze overnight. As we all know, when water freezes, it expands, adding more pressure stress to the road and road bed, causing more and more damage. The end result is potholes, and in extreme cases, sinkholes, which can swallow a car without warning. This is the reason for reduced weights during the spring thaw season. Lower weights cause less stress to the road, and reduce the damage when the road surface is the most vulnerable.
