On a snow - covered road, drivers are usually cautious, but many take risks on snow - free roads, unaware that such ice may have formed.
Lumikattega maanteel on sõidukijuhid tavaliselt ettevaatlikud, ent paljud kaotavad ettevaatuse lumevabadel teedel, teadmata, et seal võib olla musta jääd.