COUNTY — Black ice, sometimes referred to as glare ice or clear ice, is a thin coating of glazed ice on a surface. Although it is not truly black, it is virtually transparent, which makes the black asphalt on roadways visible through it. The typically low levels of noticeable ice pellets, snow, or sleet surrounding black ice means that areas of the ice are often practically invisible to drivers.
Because it represents only a thin accumulation, black ice is highly transparent. Unlike snow or slush that generally accumulates in greater densities, black ice is incredibly difficult to see. Black ice is often interleaved with wet road, which is nearly identical in appearance. For this reason, it is especially hazardous when driving or walking on affected surfaces.
Bridges and overpasses can be especially dangerous for motorists. Black ice forms on bridges and overpasses first because air can circulate both above and below the surface of the elevated roadway, causing the bridge pavement temperature to drop more rapidly. Road warning signs with the advisory “Bridge Ices Before Road” indicate potentially dangerous roadways above bridge structures.
Winter driving conditions can be tricky for even the most experienced drivers. While a snow-covered road can be an obvious driving hazard, a road that just looks wet can also be deceivingly slippery.
Black ice is a dangerous wintertime hazard because the icy road may not always be visible to the driver. Melted snow or ice that refreezes may still look deceivingly like a dry road. And temperatures don’t have to be below freezing for black ice to develop. Black ice can occur if temperatures are near the freezing mark — or even a few degrees above it.
While a shiny road surface indicates an obviously wet or icy road, a road covered with black ice will look a little different. Keep an eye out for pavement that is slightly darker and a little duller looking than the rest of the road surface — this may indicate that black ice is present. Because black ice is so tricky to detect, a driver may not realize there is an icy road surface until his car begins to slide. Here are some winter driving safety tips in the event you encounter black ice:
• As soon as your car begins to slide on black ice, take your foot off the gas pedal. In fact, the last thing you want to do is give your car more gas. It is very important to slow down when you are driving on black ice or in any other winter road conditions.
• Don’t slam the brakes. While it may be a natural instinct to slam on your brakes, this will only cause your car to lose control and slide even more. Tap the brake pedal lightly instead of pushing down hard on it.
• Look for trouble spots ahead. If you have an idea that there may be black ice ahead (if you see cars ahead of you sliding, for example), downshift to a lower gear before you come onto the black ice. The lower gear will force you to drive more slowly and it will give you better control of your car.
• If your car does begin to skid on the ice, turn the wheel in the direction of the skid. This should help to steer your car back on the right track.
• You can improve your visibility by clearing all snow and ice from your vehicle. Be sure to remove ice and snow from hood, roof, trunk, turn signal lights, tail and headlights, windows, mirrors and fenders. Use your low beams when driving in an ice or snow storm. You’ll have better visibility.
• Allow for greater stopping distance during snow and ice storms. In order to bring your car to a safe stop, you must allow 8-10 seconds between you and the vehicle in front of you.
• Remember that posted speed limits are only to be followed during ideal weather conditions. Slow down while driving on snow or ice.
• When driving uphill on ice, pick a path that will allow the most traction. Monitor vehicles in front of you and steer clear of areas where they spin wheels or slide backward. Unpacked snow will give most vehicles sufficient uphill traction.
• To maintain control on curves and turns, reduce speed just before the turn. Any sudden acceleration or deceleration during a turn could send you into a skid.
• Never brake while driving on ice. If you are approaching a patch of ice, brake during your approach. Applying pressure to your brakes while on ice will only throw you into a skid.
• Maintain your tires. Tires that are in proper working condition and are adequately inflated provide better traction.
Of course, unless you absolutely have to be on the roadways, it is best to remain off of them until weather conditions improve. Drivers can get up to date information about road conditions on the SC DOT website at http://www.scdot.org/.