All at Once, It's Winter

That's because having some precipitation first helps keep the chemicals in place on heavily traveled roads, said Branco Vlacich, who heads maintenance for VDOT's Northern Virginia district. Otherwise the salt would blow away, or be carried away by tires, and the magnesium chloride, which allows the salt to work at lower temperatures, could evaporate, he said.

County officials in Maryland, which maintain local roads, said there was little or nothing they would have done differently. Road crews were generally out by the time the snow started to stick, they said.

Prince George's County had 150 snow-removal trucks on the roads at 6 o'clock. Anne Arundel County deployed trucks at 7 and dropped 100 tons of salt by noon. Montgomery County had trucks on the road within 45 minutes of the first flakes.

"We were prepared," said Tom Pogue, public works spokesman in Montgomery.

Prince George's County had pre-salted hills, bridges and other areas prone to ice, said public works spokeswoman Susan Hubbard, who reported no major problems on county-maintained roads.

District transportation officials said they had crews out at midnight Wednesday applying a brine solution and salt on city roads. which helped. "We're lucky. The city's a heat island. Our road temperatures are warmer than in the suburbs," said Emeka C. Moneme, director of the D.C. Department of Transportation.

Bad driving also contributed to yesterday's problems, officials said.

"We continually are seeing single vehicles running into guardrails. That's one thing and one thing alone: people driving too fast for the conditions," Buck said.

As of the late evening, several counties in Maryland reported some of the heaviest snowfall in the region. The National Weather Service estimated that more than six inches fell in Glen Burnie, and that about five inches fell in Frederick, Montgomery and Howard counties. In Virginia, the service reported four inches in Arlington and 3 1/2 in Vienna.

Some took advantage of their car-bound captivity.

Kathy Morford, 50, of Haymarket, who teaches third grade in Centreville, tried to make use of her time as she crawled along I-66 at about 6 m.p.h.

"I'm from Louisiana, so I called my family" to catch up, Morford said, adding that the trip, which took more than an hour, took just 20 minutes Tuesday. "Good thing I've got lots of minutes on my cellphone."

Staff writers Jonathan Mummolo, Tom Jackman, Chris L. Jenkins, Daniel deVise, Bill Brubaker, and Raymond McCaffrey and Clarence Williams contributed to this report.