Tuesday, 4 March 2008

From theory to fact.

One of my first posts under the guise of Closet Liberal attacked what I believe is the myth of the rubber necker. Conventional wisdom holds it that when there is a traffic jam, its because people are slowing down too much to look at a roadside distraction (accident, car pull over, etc.).

I surmised that braking is a cumulative effect. When the first driver on a scene sees something, their first (understandable and desirable) reaction is to reduce speed. Since human reaction times are slower, and we tend to over-react, the next person behind slows down and slows down more than the leading driver. Cascade this all the way back in heavy traffic and you reach a point where cars are stopping completely. In other words, traffic jams are a systemic issue related to traffic density and carrying capacity of the road involved.

As part of my post I asked if anyone had crunched the numbers to prove my theory.

Now someone has done something better, they experimented.

"The researchers in Japan used a circular track with a circumference of 230m. They put 22 cars on the road and asked the drivers to go steadily at 30km/h around the track. While the flow was initially free, the effect of a driver altering his speed reverberated around the track and led to brief standstills."

I do so love being right.

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