A Unified Perspective on Traffic Flow Theory, Part II: The Unified Diagram

Over more than half a century, traffic flow theorists have been pursuing two goals: (1) simple and efficient models to abstract vehicular traffic flow and (2) a unified framework in which existing traffic flow models fit and relate to each other. Continuing these efforts, we report our humble understanding in a trio of papers. The first paper (Part I) introduced a Field Theory with an emphasis on traffic flow modeling at the microscopic level. This paper (Part II) uses the Field Theory as a framework to relate existing microscopic and macroscopic models to each other. As such, a unified perspective can be casted on traffic flow modeling with bridges not only within but also between microscopic and macroscopic levels. The third paper (Part III) provides numerical and empirical results of the Field Theory and benchmarks some traffic flow models presented in the Unified Diagram.