I read about this in the news each winter when someone ventures cross-country over the mountains unprepared. All too often it starts when a driver thinks, This road on the map looks like it might be a shortcut...
Here are a couple of tips I've learned over the years from winter travel and also examining the case histories of those who've become stranded in the snow:
1. A few minutes of prep in your driveway prior to leaving can save you hours or days of suffering in the wilds. This means loading up your vehicle with a sleeping bag or wool blankets, insulated winter boots, mittens, wool cap, parka, extra wool socks, and calorie-rich foods such as PBJ, cheese, etc.
2. Bring a thermos with hot chocolate and a few tablespoons of butter. This is the classic hypothermia recipe if you start to get chilled. The sugar revs up your metabolism in minutes while the butter provides fuel over the next hour. Folks who work in the cold, like construction workers, would do well to have this brew with them.
3. Bring a shovel and a jug of cat litter or sand. The cat-litter or sand can help provide traction under your wheels if you get stuck in ice. I'd also bring a roll of duct tape and a Mylar blanket (more on this later).
4. A Nu-Wick candle, which is non-toxic, can provide up to 144 hours of light and help to warm the interior of your vehicle, or even boil up water. We have these in each of our vehicles along with a small 32-ounce cookpot for melting snow. Just keep in mind you need to have proper ventilation, so crack a window slightly open when using a candle.
Let's say you do all this and something beyond your control happens that thrusts you into a roadside emergency in the cold. What should you do?
I'd recommend staying with your vehicle rather than walking out because your car is a tremendous survival shelter and resource. Run your engine every 15 minutes on the hour to rewarm your body and conserve fuel. Again, crack the window and make sure the exhaust pipe is clear of ice/snow to prevent carbon monoxide poisoning.
Use duct tape and the Mylar blanket to seal off the unused portions of your vehicle's interior. Do this by taping up the blanket behind the passenger and driver's seats. Why heat the whole van or SUV when all you need is where you are sitting?
When the weather clears, make a huge ground-to-air signal panel in snow near your vehicle. Stomp out a 60-foot-plus X on the ground, and then fill it with sticks or pine boughs to provide contrast and help searchers flying above to find your location. With the weather clear, you may also want to build a fire (well away from your vehicle!) to melt snow, use for signaling if you hear a plane, and to conserve your vehicle's fuel.
A lot of roadside mishaps in the backcountry can be prevented by having a well-stocked vehicle and by avoiding the "shortcut" syndrome when trying to negotiate roads in the winter.