Intelligent Traffic Management?

jcwren asks: "I was driving to work one morning, cursing the so-called 'traffic engineers' who configured our glorious network of traffic lights, when a few questions occurred to me. Do cities actually have a traffic management system that's either learning or adaptive (fuzzy logic, pseudo-AI, whatever)? I seem to remember that years ago that Phoenix had a far better traffic control system than Atlanta has ever had. What are peoples' thoughts (logically, not emotionally) on how traffic is managed in their cities?"