Continuum modelling of transportation networks

The standard discrete transportation models, which attempt to determine traffic flow on every link of a transportation network, are inapplicable to complex dense urban networks, in view of the amount of computation involved. In this paper we adopt a radically new point of view and construct a family of models based on the assumption of continuous traffic distribution over the network. We derive the flow conservation equations and the equilibrium conditions for user-optimized and system-optimized networks.