1Use of Simulation in Planningl

SIMULATION is a technique for representing the workings of a complex system such as the governmental activities of a large clt,y or the total economy of a multi-county region. Three types of simulation are identified in this presentation-- computer simulation, games and gaming simulation. Computer simulation is based on the man~pulative capabllltles of modern computers to explore complex, mathematical models of urban and regional systems. In games, on the other hand, the behawor of decision makers is simulated by condensing their roles Into a few repre-sentative forms and by applylng rules that closely depict their real llfe constraints. In gaming simulation, however, the computer prov~des both an environment for the game and a laboratory for expcrlmentatlon. Opera-tional gaming, finally, includes both games and gaming simulations and, hence, Involves the playing of games with or without usc of a computer. Our intent is to relate the three types of simulations to plannlng. We are trying to attain a better understanding, not only of what happens (which, for a complex system is already a difficult task) but, also, how and why these happenings occur. Our intent, therefore, IS to ident~fy practical uses of simulation in coping with and understanding problems of local and regional change and development. Our presentation 1s in two parts. Computer simulation models are 2presented, first, starting with the Chicago Area Transportation Stud,y (CA IS) Model as a prototype of the spec~al-purpose plannlng model (14, 69]. Computer model characteristics are described further with reff’rence to the recentl