Chart of the Day: The Traffic Jam Nonlinear Flow Loop



This chart is basically a re-drawing of the one that I put up last week, depicting flow rate vs. density for a traffic jam. The difference here is that it depicts a non-linear time sequence, showing how traffic flow increases, destabilizes, and then falls into a separate “congested” regime with lower flow rates.

Coincidentally, it is precisely this kind of behavior that ramp meters seek to control. If ramp meters can keep flow rates from plummeting into the “post-critical” phase of the cycle, then everyone traveling on the freeway is better off. In other words, when it comes to freeway behavior, congestion is a one-way street (topologically speaking, of course).

PS Image comes from Philip Ball’s interesting book, Critical Mass. is a non-profit and is volunteer run. We rely on your support to keep the servers running. If you value what you read, please consider becoming a member.


  1. Chart of the Day: Traffic Flow v. Traffic Density (Unstable Traffic States) | - June 3, 2014

    […] is the last of the chart triptych about the nonlinear dynamics of traffic congestion, again from Philip Ball’s popular science […]

  2. Sunday Summary | - June 8, 2014

    […] Charts of the Week: TV Watching vs. Giving Drivers the Finger illustrates an interesting correlation; posts by Gender shows just that and should be viewed in conjunction with Encouraging Diversity.  Plus two charts about traffic: Traffic Flow v. Traffic Density (Unstable Traffic States) and The Traffic Jam Nonlinear Flow Loop. […]

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