Why spontaneous traffic jams are like detonation waves


We’re all familiar with phantom jams, traffic blockages that arise with no apparent cause and that melt away for no discernible reason.

Today Ruben Rosales and pals at MIT and the University of Alberta in Canada coin a new term for the waves that cause these hold ups: they call them jamitons.

And jamitons turn out to have an interesting property: they are self-sustained disturbances consisting of a shock matched to vehicle speed.

If that sounds familiar, it’s because you’re reminded of the way in which certain types of transonic disturbances can be self-sustaining. In the world of a chemists, these are known as detonation waves.

Rosales and co say jamitons and detonation waves are mathematical analogues.

That sounds interesting and useful and perhaps one day it will be. But you wouldn’t guess it from this paper.

Rosales and friends are unable to run with their analogy in any useful way. They say that the existence of jamitons in traffic flow are an indication that dangerous vehicle concentrations may occur (no, really?).

And they conclude: “such situations may be avoided by judicious selection of speed limits, carrying capacities, etc” (Wow!)

In other words, spontaneous traffic jams may cause avoidable crashes. Nothing gets past these guys.

Ref: arxiv.org/abs/0809.2828: On “Jamitons,” Self-Sustained Nonlinear Traffic Waves

3 Responses to “Why spontaneous traffic jams are like detonation waves”

  1. […] Physics arxiv Blog has a critical review of what I believe is the same […]

  2. […] Why spontaneous traffic jams are like detonation waves […]

  3. Wim says:

    Other explorations of these phenomena here (TU-Dresden) and here (Science Hobbyist).