Brazil nut effect in traffic

Granular convection in traffic movement.

Simply put the Brazil nut effect is this: Upon shaking, the larger nuts in a cereal/muesli bag come up to the surface and the smaller ones settle at the bottom. This granular convection has been studied in quite a bit of detail as the references in the wiki page suggest. My understanding of it involves movement of smaller particles within the gaps between the larger ones and those channels lead to gradual settling of small particles, or equivalently larger ones rising to the surface.

What’s that got to do with traffic? The effect has already been observed/studied in other areas like Geology and Astronomy. I see a connection with the traffic situation in India.

The inhomogeneity in vehicular sizes leads to a similar phenomenon wherein two-wheelers settle in front at a junction and larger/heavier vehicles are left behind. The parallels are there: a driving ‘force’-like thing similar to gravity responsible for moving vehicles in the same direction, signals appearing (ir)regularly function like shaking. The question is: Which simulation model reproduces this behaviour?

Murthy O V S N
Murthy O V S N

Physicist and educator in Bengaluru, India