Cut down on hassles by planning a detailed route that avoids construction detours and delays; interstate highway Web sites should provide the necessary information. Reduce your odds of getting lost by writing out directions clearly and legibly. Or print out instruc-tions from mapquest.com or yahoo.com.

Drive a Clean Machine

It won’t be a very merry Christmas if you spend the night before in the breakdown lane of the interstate. Prevent trouble by making sure your car is in excellent shape, with good tires, new wiper blades and a well-functioning heater and air-conditioner. “Unlike traffic congestion, the condition of your car is something you can control,” says Patricia Mokhtarian, Ph.D., an expert on commuting behavior at the Institute of Transportation Studies at the University of California at Davis.

Get the Timing Down

Make your exit between rush hours and leave home with plenty of time to spare. “Adjust your expectations,” advises Mokhtarian. “Be prepared for stop-and-go traffic, rather than mentally fighting it.”

Stay Comfy on the Road

Shift your weight around in your seat, roll your shoulders, crane your neck, extend your arms. If you’re the driver and can safely put the car on cruise control, do exercises to relax your leg muscles and back. Extend one leg to the floorboard, push against it for three counts, then relax. Do a set of 10, then shift to the other leg. If you typically get back pain on long trips, buy a seat back massager. “It plugs into your cigarette lighter, and you can get one with heat,” says Sue Elliott-Sink, spokesperson for the Specialty Equipment Market Association. Try the HoMedics 5 Point Car Seat Back Massager, $40, drugstore.com.

Don’t Speed

You’ll end up frazzled. Upping your pace from 60 mph to 70 mph reduces a 40-mile commute by just six minutes.

Bring Replenishments

Keep water and a few healthful snacks (whole-grain crackers, string cheese, nuts, fruit) on hand. “Hunger can make you irritable,” says Elliott-Sink. But limit the stimulants: Caffeinated beverages increase your need to make frequent bathroom stops. This can be annoying and may boost your anxiety about arriving on time.

Provide Entertainment

Pack plenty of books and games for the kids. Program the radio to favorite stations and load your CD carousel or tape player with popular music. Or listen to audiobooks (free or low cost from your library).

Eliminate Distractions

Empty trash from the car at every stop. Don’t let items clutter or roll around the floor, where they could interfere with your ability to apply the brakes.