I had not seen the post, so your reason for asking is clearer now, but I don't think you're understanding what I mean by "it doesn't make a difference." My point is that you cannot look for one without looking for the other. You can't look for a space between cars without looking to see where the cars are. Ergo, you have to look for both. And yes, you can look for the cars without looking for a collision, because you can't prevent one without knowing where they are. Which is what I'm saying--it's all the same thing.