But Wednesday's storm added another factor to the mix, as some local officials blamed the federal government's decision for creating an early rush hour at exactly the time the snow came down in an unusually intense burst.
"I wonder how many of these we have to go through before we learn that if we keep people until 4 p.m. and dump people into the middle of the chaos, this is going to happen," said David F. Snyder, vice mayor of Falls Church, who has focused on emergency preparedness as a member of the Metropolitan Washington Council of Governments.
John Lisle, a spokesman for the D.C. Department of Transportation, said the government should have pushed workers to leave earlier. "Looking back, I wish we had told people at 3 o'clock, 'The storm's going to hit at 4 p.m. If you don't leave by then, you may not get home,' " he said.
But John Berry, the federal government's personnel management director, stood by his decision to release workers at 3 p.m. "The reality is, with human nature being what it is, many people did not choose to take advantage of the option" to leave early, he said. "They looked out the window, saw no snow and said, 'I can wait until I see snow.' "
The storm had been predicted all week, but hours of rain washed salt and other chemicals off roads that had been treated Tuesday night. Then, just as hundreds of thousands of federal workers were being sent home early, a sudden dump of heavy, wet snow - no more than half a foot - turned major thoroughfares into icy, slushy parking lots.
Cars and buses stalled along 16th Street NW and Connecticut Avenue, four tractor-trailers jackknifed on the Capital Beltway, and wreckers towed 17 trucks near the Wilson Bridge, scenes duplicated by the dozens on major commuter routes from Annapolis to Dulles.
As frustrating minutes turned into hours, commuters by the hundreds ran out of gas or left their cars, making it even more difficult for plows and tow trucks to get to arteries such as the Beltway, Interstate 66 and the George Washington Memorial Parkway.
"It just felt hopeless," said Shaun Gholston, 33, who said it took him 11 hours and 19 minutes to drive from Rockville to his Capitol Hill home, which usually takes 55 minutes. "Like I was never going to get home."
Wednesday began with a burst of bravado, as D.C. transportation officials said they were ready for the storm. They, like their suburban counterparts, had spent the night treating major roads to keep them from freezing. But then came the rain. Then the temperature dipped below freezing, the rain turned to snow and the federal workers hit the roads. Re-salting the roads was now impossible. In the District, traffic control officers were unavailable to man intersections because they had been ordered to drive plows, which immediately got stuck in traffic.