Multi-Commodity Nash Flows Over Time

Abstract: Motivated by the dynamic traffic assignment problem, we consider flows over time model with deterministic queuing. Dynamic equilibria, called Nash flows over time, have been studied intensively since their introduction by Koch and Skutella in 2009. Unfortunately, the original model can only handle a single commodity, i.e., all flow goes from one origin to one destination, therefore, this theory is not applicable to every-day traffic scenarios. For this reason we consider Nash flows over time in a setting with multiple commodities, each with a individual origin and destination. We prove their existence with the help of multi-commodity thin flows with resetting. This proof gives some interesting structural insights into the strategy profiles underlying the equilibria, as they emphasis the inter-commodity dependencies. Finally, we show that the two special cases of a common origin or a common destination can be reduced to the single-commodity case.