ATLANTA — There are bad commutes, and then there is what happened here this week.

When a light snow started falling early Tuesday afternoon, Saquana Bonaparte, 31, left her factory job and headed out to get her daughter from school in one of the city’s northern suburbs.

She ended up inching along in her car for almost 12 hours and survived on a half bag of beef jerky and a small bottle of Mountain Dew. Unable to get to a bathroom, she did what she had to do as she drove. Twice.

Ms. Bonaparte spent the night on jammed roads with tens of thousands of other desperate Atlanta-area drivers who had never seen anything like the sheet of ice that coated the city.

“It was like something you would see if they told you the plague broke out and you had to run for your life,” she said.