lane exchange

When 2 cars in different lanes both switch into their counterpart's lane at the same time.

eg: Car A moves from the left lane into the right lane. At precisely the same time Car B moves from the right lane into the left lane.

Commonly the cars involved in the lane exchange are in close proximity (1-3 cars apart) however an exchange can take place over greater distance without either party being aware of it.

The lane exchange is Mother Nature's way of returning traffic pressure to equilibrium.