Hmm. Interesting. I have always contemplated this problem. First, I want to simplify the problem a bit and hope it'll apply to traffic jams. I think the problem is human reaction time. I must be missing something but hardly people talk about this. (although my solution might not be feasible). Let me explain.

So, lets say you are stopped behind 30 cars and the first car is waiting for the red to turn green. Now, as soon as it turns green, it takes a second (or two) for the first car to start moving. After that second, second car adds another second before starting to move. Based on this, you won't move your car until 30 seconds have passed. Isn't this one of the big issue? If all of 50 cars instantly start driving once it hits green, wouldn't it reduce traffic jam greatly. Now, I do realize this is not feasible but if computers were controlling the car, 50th car can move instantly after green.

On a side note, I realize the bottleneck situation can't be solved easily BUT again, I think human reaction (response) time is a huge part of it in most of these scenarios. If computers were driving, I wonder if we can have 10 times the car we have today without traffic jams.