So, I'm watching Criminal Minds on A&E. Some woman just got ran down by a truck that was chasing her down a road with forest on either side. This brought something to mind.

 Why is it that when a person on foot is being chased by a vehicle on TV or on the big screen, they always run down the middle of the road? Is there some sort of force field on either side of the road that keeps them locked in? Are they so panicked that they can't run forward and to the left or right at the same time? What's the deal?