A hazard often overlooked but very associated with our recent spell of cold and warm winter weather is what is generically referred to as ‘Black Ice’. But what is black ice? How does it get there and what can we do about it?

Black ice is not, of course, black at all. It gained this moniker from its most common source of incidents, the roadway. It is, in fact, a thin layer of ice with very few air bubbles, and so clear that it’s transparent. This makes the black road beneath it crystal clear, looking either deceivingly normal or slightly wet in appearance. There are typically low levels of ice and snow nearby, making the roadway or walking area look clear.

The MOST deceptive part is, however, that it can form very quickly even when daytime temperatures are above freezing! This is because in the early day the warm air will start to melt the upper layers while the ground, still holding in the cold, keeps the underneath ice cool longer. Likewise, at night, the air cooling down quickly freezes the water on top back into a clear glaze, which you dismiss because of daytime temperatures.

But dismissal is the most dangerous part of black ice, on foot or in a vehicle. A slip and fall causes enough trauma when your body connects with the ground (still unprotected by any layer of snow or softer ice which normal winter conditions produce), but in a moving vehicle black ice can be a disaster. It’s estimated that the stopping distance for a vehicle on black ice is NINE TIMES that of a vehicle in ordinary conditions, and black ice first indicates it’s presence by a total absence of vehicle control.

Fortunately, we are not without resources of our own. Salt and calcium chloride can make driving and walking much safer in changing weather conditions, and an alertness while travelling can prevent most incidents from occurring. Remember that stopping and handling in a motor vehicle will be greatly impaired on black ice, and drive slower and more carefully in areas where it’s been reported.

Finally, remember that bridges freeze before roads, making them areas for extra attention in the winter! This is because cold air is able to circulate both above and below the accumulated moisture, freezing it faster. Drive safely on all roads, with attentiveness and care, and make the most of our winter!