Monday, November 10, 2008

Stopped Traffic--What Would Charlie Do?

We all have our own particular annoyances when driving. Mine is what I refer to as the “Imaginary Slow Down Zone,” affectionately referred to as ISDZ’s. This happens on highways, when the traffic comes to a crawl. You slowly approach the area where everyone starts to speed up, and you look around for an accident or any other reason which could have caused the slow down, but there is nothing there. Cars just resume speed. This phenomenon happens quite frequently in Columbus, Ohio, so I was sure that this had to be an isolated thing.

Columbus has the worst drivers on the planet. Particularly so, if you can see a #3 decal displayed anywhere on the vehicle. This type of driver suffers from the disease called, “the NASCAR” syndrome. They weave in and out of lanes at high speed, as if headed for the checkered flag. Severe accidents are so common in Columbus that they have a section on the nightly local news broadcast, which is titled, “Car Crash Dejour.” Points are given based on death count (this is not quite true, but just wait for sweeps week).

Now I admit that there have been many times when I used to commute to work on I-270, when the slow down ended and I had to pass six or more mangled cars and at least two or more emergency helicopters parked on the medium revving up for take-off, so I don’t want to take this too lightly.

I used to think that we were so gun-shy in Columbus that the ISDZ’s were some sort of post-traumatic-stress thing. But my wife and I found ourselves in one, on I-77 in West Virginia recently. Not only did the traffic come to a crawl, but it actually came to a complete stop. I really thought that there had to have been a terrible accident ahead when the eighteen wheelers turned their lights off. Surely they knew the scoop and were getting ready for a considerable wait. It was dark (really, really dark). After I finally came to a sense of acceptance, the traffic started up. So I waited to see what in the world had caused this. As we approached the spot where all the cars started to gain speed there was nothing. I mean NOTHING!

So I decided that there has to an explanation for his irritating phenomenon. The next step was to ask: what would Charlie Epps do? For those of you who are not familiar with Charlie, he is the fictional character on the TV Show “Numbers.” He is a math genius who can figure the mathematical roots of any conceivable problem.

So here’s what I found out to my dilemma--

There actually is a mathematical model that shows that traffic jams, like ISDZ’s, are mostly caused by a single driver who brakes too much when faced with any number of unexpected events. The driver behind him will also slow down and then the next, until the road is totally blocked several miles back. The traffic jam moves backwards, creating a “backward traveling wave,” miles upstream from the initial braking, several minutes after it was triggered. So, in other words, when someone taps their brakes, the traffic may come to a stand-still several miles behind them. Now it is pointed out that it is the heavy braking, usually caused by a driver reacting to some idiot with the “NASCAR” syndrome who has cut them off, that can affect traffic flow for many miles.

Thanks to the work of Dr. Gabor Orosz of the Dynamical Systems & Control research institute of the School of Engineering, Computing and Mathematics at the University of Exeter, UK, I can now impress my colleagues, friends, and family with the answer to this mystery, the next time one of them complains about all the unexplained traffic slow downs on the highway.

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