Black ice: ‘Be alert for its pres­ence’

Sackville Tribune - - WHEELS - BY RICHARD RUS­SELL WHEELS

One of the worst sit­u­a­tions any driver can en­counter is a sur­prise.

When that sur­prise is a to­tal loss of trac­tion or grip the re­sults are fright­en­ing and can of­ten lead to a crash.

The dic­tio­nary de­scribes black ice as “a thin, nearly in­vis­i­ble coat­ing of ice that forms on paved sur­faces.”

It can be all but in­vis­i­ble, and even blend in nicely with grey or darker sur­faces.

Early and late win­ter, are the most likely pe­ri­ods when we’ll en­counter black ice. It usu­ally forms at dawn or just prior to dusk, when a mil­lime­tre thin layer of mois­ture on the road is cre­ated by a dif­fer­ence be­tween air and sur­face tem­per­a­tures — con­den­sa­tion.

This tiny and of­ten in­vis­i­ble layer of mois­ture can also ap­pear at other times of the day and year as well. But it is par­tic­u­larly prom­i­nent at this time when the sun still has some punch but the ground is cool.

An­other sit­u­a­tion, which of­ten sur­prises mo­torists, oc­curs when the road is damp on a sunny day.

When the sun is out, it gen­er­ates enough sur­face heat to main­tain the mois­ture in a liq­uid state. But when it goes be­hind a cloud or is shaded by a tree or other ob­ject, the re­sul­tant mi­nor drop in tem­per­a­ture may be enough to con­vert that liq­uid to a solid — ice. Even a sin­gle de­gree can do it.

We are sep­a­rat­ing black ice from “nor­mal” ice, which is frozen sur­face wa­ter — but both re­quire the same re­ac­tion and de­gree of cau­tion.

The first step in sur­viv­ing an en­counter with black ice is to be alert for its pres­ence. If the road is damp and the ther­mome­ter hov­er­ing near the freez­ing point, look well down the road for signs of shady ar­eas cre­ated when the sun is blocked by an ob­ject.

Slow down and be very wary in­deed. Even if the road is dry, such shaded ar­eas might still be damp and con­tain the dreaded black ice as they haven’t been dried off by old sol.

An­other small re­minder you may be about to en­counter a prob­lem, is to watch on­com­ing ve­hi­cles for signs of mois­ture. Are their wipers on? Is there mois­ture drip­ping off the un­der­car­riage? Are the on­com­ing mo­torists driv­ing slowly or seem­ing to be dis­play­ing ex­tra cau­tion?

All of th­ese might be an in­di­ca­tion there is an un­pleas­ant sur­prise wait­ing for you over the next hill or around the com­ing cor­ner. This is espe­cially likely at dawn and dusk when the sun is low on the hori­zon and even mi­nor el­e­va­tion changes will cre­ate shad­ows and likely black ice spots.

If you do find your­self com­ing unto an area of black ice, slow down and try to keep the steer­ing straight, if pos­si­ble. Slow­ing down, means get­ting off the ac­cel­er­a­tor.

Do this smoothly, don’t snap your foot off the gas — this will trans­fer ad­di­tional weight unto the front tires too quickly, in­creas­ing the like­li­hood they won’t be able to cope with all the forces placed on them when they hit the ice.

If you have time to brake be­fore the ice, do so, but if not, avoid the brakes un­less you have ABS. If so-equipped you can ap­ply the brakes at any point.

If you en­counter black ice with the steer­ing and thus front wheels turned, you will likely en­counter what is known as un­der­steer — the front of the ve­hi­cle will keep go­ing straight re­gard­less of steer­ing in­put.

As with all- ve­hi­cle- con­trol is­sues, the main trick is to avoid sud­den move­ment and panic. Ease off the throt­tle. Avoid the nat­u­ral re­ac­tion to turn the wheel even more; do just the op­po­site — un­wind the steer­ing slightly, turn­ing in the di­rec­tion the ve­hi­cle is go­ing.

While this may be coun­ter­in­tu­itive, it will al­low the treads of the front tires to as­sume the cor­rect re­la­tion with the sur­face of the road, and re­gain grip sooner as speed comes down.

Be ready for the sec­ondary re­ac­tion when the front tires do re­gain grip as they come into con­tact with a bare road af­ter cross­ing over a patch of black ice.

If the steer­ing wheel is turned, the front tires will sud­denly have trac­tion and snatch the ve­hi­cle vi­o­lently in the di­rec­tion they are turned.

Re­mem­ber — look for con­di­tions that will cre­ate black ice and avoid panic and sud­den move­ment should you en­counter it.

123RF

The first step in sur­viv­ing an en­counter with black ice is to be alert for its pres­ence.

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