Traffic ~ Theories on why it happens and why it suddenly clears up

  We ended up in traffic today. Strange thing traffic. I wanted to talk about a few theories I have about traffic and why it happens. Naturally I could just go and Google this and eventually I will but for today we’ll just have some fun writing out the mad ramblings of my overheated mind.

  Someone in a cement truck decided that they wanted to take a turn at presumably 30 or 40 miles per hour. Inertia sets in and the vehicle topples over and blocks the road leading off of the highway to 1st street. A single off-ramp blocked for miles. You wouldn’t think this would cause crippling near stopped traffic.

  You wouldn’t would you?

  You’d be wrong.

  The road went from completely fast moving and jovial to a dead grind for us at 2 in the afternoon. 2 in the afternoon on a Tuesday is not a special time. Lots of people aren’t getting off of work, lots of places aren’t getting supplies, basically nobody is out to lunch. This is what I would call downtime. Yet in this least active of times there are cars shoulder deep in one another.

Theory #1

Why stop and go traffic exists.

  I am not entirely convinced that oncoming traffic has a major influence on traffic. My reasoning for this today is that there were no onramps for ages and ages and yet we were still moving stop and go (indeed the next ramp connecting us to other roads was an offramp and it had a cement truck across it).

  Instead I think it has to do with impatience. People accelerate too quickly and bunch up with the cars in front of them. This results in the cars behind them bunching up and the cars behind that bunching up. Effectively you are creating that effect you get when you snap a wire. The parabola that travels down the wire is (in this case) the “stop” in the stop and go traffic. Each time a car accelerates too quickly they will have to stop and every single car behind them is hit by this phenomena.

  In this respect it only really takes one impatient person to start the chain and screw everyone. The ideal traffic solution if this is the case is to move slow enough that you never need to break. I actually spent the vast majority of our time in traffic crawling forward because my average forward momentum was just as efficient as the gun it and slam on the brakes approach of the pickup truck in front of us.

  I know I mentioned that offramps probably don’t have a major impact but I’m about to contradict that a bit. I also think that this accordion effect is caused by people switching lanes. There is a statistical reason why you think other lines are moving faster. Here is a video about it actually.

His videos are all great.

  You’ll note he mentions that people act unwisely and it makes their lives worse. That’s a theme for most confusing problems in life. In the video he mentions that a single person stopping will cause everyone behind them to be boned. Now imagine if that same problem were magnified. People could jump the line anywhere they wanted at any time they wanted and suddenly the density of the lighter line increases.

  In this way the line an impatient person is in will always be the worst line because impatient people will always flood the line that is moving.

Theory #2

Why does traffic just suddenly vanish?

  It happens every time. You are in traffic and then something arbitrary happens (in our case it was driving past the semi. The amount of places people could turn off had increased by 0% and yet traffic completely vanished at this exact moment). This doesn’t make sense when you take it at face value. There was traffic and now there suddenly isn’t traffic. Nothing has changed from your previous minute to your next. In theory there should be consistent  traffic until off-ramps start lightening delays. But we had 0 additional off-ramps to lower the quantity of cars in these lanes.

  My theory is that traffic acts like a zipper. You have the initial cause for the traffic. In this case that cause was the cement truck overturning like a fool. Next there is confusion as people try to turn off but can’t and you create a point of congestion. This congestion will first build up, the build up would be you zipping the pants all the way.


  If you were a person at the moment of traffic conception you would immediately understand why traffic let up. However the odds of you being one of those people more than once or twice in your entire life is pretty much slim and none. Think about how many times you’ve seen a major accident go down and cause traffic. Not many times I imagine if ever.

  The moment this initial cause of traffic (in this case confusion) is relieved traffic will begin to dissipate. It will do so from the front first because this is where you have the least number of chances for people to accelerate too quickly and cause the whip effect from the first theory.

  The traffic will then “unzip” backwards towards the end of the traffic length.


  Imagine where the line separates is when you experience the “sudden” end to the traffic. Statistically most of the time when you hit the moment of the unzip you will not be near a source that would reasonably have influenced the traffic positively or negatively. For you the traffic just was and then suddenly was not. Once the zip hits the back of the traffic the entire episode vanishes as if it had never existed in the first place.

  So that’s that. Those are my two theories on traffic. They might be right and they might be wrong. Those are really the two most likely outcomes to their validity.