[baldfat]

Traffic happens when distances are increased. Someone sees a slight slow down and they then slow down and give 20 seconds of space (I have seen cars and trucks give 200+ feet of distance for some odd reason. Then the flow is cut down to 10 cars a minute instead of 120.

[lotsofpulp]

Yes, but you can't fix that. And the faster you go, the longer it takes to stop (to the power of 2). Rule of thumb I've read is 1 car length for every 10mph to be able to stop in time in case if accident up ahead.

Obviously safety gets triaged with need to get somewhere in a reasonable amount of time, but at a certain point you hit a maximum and since we can't drive in unison, there will be a rubber banding effect.