Why a Traffic Flow Suddenly Turns into a Traffic Jam (2013)

In setting out to understand how a phantom traffic jam forms, we first have to be aware of the many effects present in real traffic that could conceivably contribute to a jam: different types of vehicles and drivers, unpredictable behavior, on- and off-ramps, and lane switching, to name just a few. In macroscopic, or “fluid-dynamical,” models, each driver—interpreted as a traffic-fluid particle—observes the local density of traffic around her at any instant in time and accordingly decides on a target velocity: fast, when few cars are nearby, or slow, when the congestion level is high. In macroscopic traffic models, jamitons are the mathematical analog of detonation waves, which naturally occur in explosions.

Source: nautil.us