Going by your response to me, and your response to Vash about how he ought to be watching where he's going, I'm going to go out on a limb and say you don't drive. No matter how observant you are, you can always end up in an accident if someone else is going to decide to be a dick on the road. I've dealt with my share of dangerously aggressive drivers and they've got the potential to cause a lot of havoc. The only comfort in that though, is that that person will end up being more at fault than you are.