Traffic Jam on a Petri Dish

A few years back I wasted hour after hour playing with the java settings, and watching "traffic" jams materialize and melt -- just like in real life. My favorite quirk: for one lane-narrowing scenario, I could make traffic flow along beautifully at 40 miles per hour, but seize up like glue at either 20 mph or 60 mph. Another fave (and very relevant to congestion pricing debates) was letting traffic flow along smoothly at, say 1,400 "cars" per hour, and then increasing traffic volumes to 1,500 -- and watching the traffic jam crystallize within moments.