That's the problem in Chicago. The lights change from green to yellow to red in like milliseconds. And because of traffic, the lights in the city cycle way faster that anywhere else I have been. AND, in most cases there are no green left turn arrows, and no turn lanes. So basically, if you need to make a left hand turn, the only way its gonna happen is if you sit in the middle of the intersection and wait for oncoming traffic to stop, and then roll through the yellow/red light. If done properly, this allows about one car to turn left on yellow each light cycle, but anyone who trains along will technically be running the red.
In my opinion, this system has ABSOLUTELY NOTHING to do with safety, and EVERYTHING to do with generating revenue for the city...
Bart