I always get off. Nothing like being stuck on an expressway with 200 other cars and trucks because some cars and trucks couldn't play nice 3 miles ahead of you. Get off the highway. Slower speeds maybe but if you get stopped you can turn around and head back. You might be able to find fuel if you need it. There may be a secondary highway paralleling the expressway that was built 50 years ago. If you are on the expressway you have only two choices when things go wrong. Sit with a whole bunch of people going nowhere or 2nd. Sit with a bunch of people going nowhere. And when was the last time you heard of a 45 car/truck pileup with multiple fatalities on a secondary highway.