Should your vehicle break down or slide off the road:
Stay calm. It’s generally safest to stay buckled up inside your vehicle. Along with protecting you from the elements, your vehicle offers protection should other vehicles slide out of control. Getting out of your vehicle and walking near a highway is dangerous any time of year.
If possible, call 911 on your cell phone. Be ready to describe your location and situation. Follow any instructions. You may be told to stay where you are until help arrives.
Resist the urge to get out of your vehicle and shovel or push your vehicle free. Overexertion can greatly complicate your situation, and being outside your vehicle exposes you to dangers.
If necessary to stay warm, run your vehicle’s engine for brief periods (make sure the exhaust system is working properly and not blocked by snow). Using portable heaters inside vehicles or other enclosed spaces can be dangerous.
Keeping your dome light on during low-light conditions can make it easier for rescue crews to find you. Remember, the storm will end. You will be found.
Wisconsin State Patrol video on things to keep in mind if stranded.