These tips are from Officer Sodimu of the Metropolitan Police Department.
"Plan ahead to avoid a bumpy road
Allow extra time in a travel schedule. Bad traffic can often be avoided with a little preparation. The heaviest travel days are usually before and after Thanksgiving, Christmas and New Year's Day. Consider taking an extra day off so that you aren't stuck in the pack. Also, try to minimize holiday stress by getting the bulk of your shopping done well before the holiday.
Make sure cars are well-equipped for travel. Breaking down in the dark, in bad weather or in the cold can crush the holiday spirit. It's a good idea to take the car in for a winter "check-up." A mechanic can inspect the antifreeze, battery, windshield wipers and other cold-weather components. Make sure that the tire pressure is at the recommended levels, as tires can be hazardous in wet weather when they are not filled to proper levels.
Think before you drive. the highways are a community. As much as we may want to think we are isolated in our steel and glass bubbles, driving is really a social interaction without words. To understand holiday driving conditions, think of the way people act outside of their cars in this time of year. Many are worried, preoccupied, hurried, distracted and all those states of mind that make them easily agitated and less careful. On the road, this means that everyone should be more vigilant than usual, give people more distance and be forgiving when someone does something rash or absent-minded. Avoid confrontations, and try not to let other drivers bring you out of the happy holiday zone.