Urban Dynamics describes an application area that is located somewhere in between World Dynamics and Industrial Dynamics. It includes application areas such as the studying of traffic flows in an inner city or along a freeway.

Most people today prefer a different world view for the description of traffic flows in the inner city, namely that of a process-oriented discrete event simulation, as this world view allows us to study better phenomena such as deadlock and starvation in a system.

Typical tools for such purposes would include ARENA, and there exists also a Modelica implementation of that tool and modeling methodology, called the ARENALib.

Yet, for the study of traffic flow along a freeway, the System Dynamics approach might still be the preferred way of dealing with such problems.

Whereas the discrete event world view follows an individual car through the system from one traffic light and intersection to the next, the System Dynamics world view discusses the problem at a slightly more aggregated level using traffic volume as its levels and traffic densities as its rates.

The Modelica implementations of the two methodologies would allow us to intersect discrete-event traffic models of an urban area with System-Dynamics traffic models of its surroundings. This application represents current research and has not much been tackled so far.

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References:

1. Kelton, W.D., R.P. Sadowski, and D.T. Sturrock (2003), Simulation with Arena, 3^rd Edition, McGraw-Hill, 672 p.
2. Prat, V.S., A.Urqu�a, and S. Dormido (2006), ARENALib: A Modelica Library for Discrete-Event System Simulation, Proc. 6^th Modelica Conference, Vienna, Austria, pp.539-548.