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If you're interested in this as a science, you might look up the studies done from the 50s, such as by M J Lighthill and G B Whitham (1955) up to Nagatani (2002), and likely even more recent studies, where traffic is modeled as a wave, among other similar phenomenon.

My personal view--and I do not personally study such things scientifically, but only from personal experience such as yourself--centers on the idea of a feedback loop, where the medium is that of tail lights (stopping). Modeling from this micro-behavior should yield the emergent behavior of waves, etc.