Simulation and molding are efficient techniques that can aid city and regional planners and engineers in optimizing the operation of urban systems such as traffic light control, highway toll automation, consensus building, public safety, and environmental protection. When modeling transportation systems like freeway systems, arterial, or downtown grid systems, planners and engineers are concerned with capturing the varied interactions between drivers, automobiles, and the infrastructure. Modeling and simulation are used to effectively optimize the design and operation of all these urban systems. In an urban simulation community workshop, citizens can work interactively in front of computers and, with the click of a mouse, walk up to their own front porch, looking at the proposed shopping mall alternatives across the street from virtually anywhere.