Black ice

Winter smoothness ( colloquially road smoothness) occurs when forming a layer of ice on the road surface or other anti-friction coating. There are several causes:

• In packed snow existing snow by pressure, for example, cars or pedestrians is already compressed to a smooth layer. Especially smooth is this layer when it thaw slightly and freezes again. Also freezing slush snow leads to icy conditions.
• Unfrozen slush leads to slip effects when he is before blocking tires (see ABS) backed up and the resulting slides that forms wedge of slush on the road surface. This risk can also arise when winter maintenance done on insufficient cleared road surfaces.
• From black ice ( freezing rain ) is when on the road any water ( puddles ) freezes
• Mature smoothness occurs when the temperature of the road surface is below the dew point and thus freezes humidity. Since bridges cool at night more, here is the danger of slippery frost is particularly large.
• When driving on ice fresh precipitation freezes on impact with the ground. If normal raindrops freeze on the cold pavement immediately, this is called Freezing rain or " black ice ". Freezing rain is caused by supercooled raindrops freeze on the ground abruptly upon impact.
• Mud smoothness can occur despite appropriate safety duties, especially in rural areas when wet soil residues are transferred from agricultural land to a road.

Warning labels (etc.) does not relieve a traffic backup agent or a cause of road smoothness of the duty to combat icy roads, to the extent this is not legally regulated differently. Most municipal regulations require residents or winter maintenance to eliminate wintry smoothness in the period 7-20 clock, on weekends from 8 clock.

An ice warning system is a device for detecting and forecasting of ice or ice hazard on roads. Such systems are installed on many high-level roads ( highways and motorways ).