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Phantom traffic jams, also known as traffic waves, occur when a small perturbation with no obvious cause results in a chain of approximately equidistant moving vehicles increasing in local density.[1] The waves travel backwards relative to the cars themselves,[2] and their underlying cause is that traffic flow is inherently unstable at higher densities.[1]
Such traffic “shock waves” were first described by Lightman and Whitman in 1955.[3][4] The following year Paul Richards independently published a similar model.[5] Both papers were based on fluid dynamics, and the model is known as the Lighthill–Whitham–Richards model.[6]
The Lighthill-Whitham-Richards model, and similar first order models, model flow as a static function of the density.[6] In more mathematically sophisticated second order models, such as Payne-Whitham and Aw-Rascle, traffic flow is modeled by the evolution of a continuous vehicle density function and a continuous velocity function, rather than individual vehicles.[1]
See also
- Boid
Computational model of flocking developed by the computer graphics specialist Craig Reynolds in 1986.s
