Proceedings of the 2003 Winter Simulation Conference S. Chick, P. J. SÆnchez, D. Ferrin, and D. J. Morrice, eds. DEVELOPMENT AND VALIDATION OF A FLEXIBLE, OPEN ARCHITECTURE, TRANSPORTATION SIMULATION Michael Hunter School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta, GA 30332, U.S.A. Randy Machemehl Center for Transportation Research 3208 Red River The University of Texas at Austin Austin, TX 78705, U.S.A. ABSTRACT Simulation has been utilized in the planning and develop- ment of almost all sectors of the transportation field. The practicing transportation community primarily relies on simulation packages, as opposed to ground up simulation development. Unfortunately, the use of these simulation packages has several disadvantages, most notably the black box phenomenon and reduced modeling flexibility. The simulation approach described in this paper lays the foundation for a transportation simulation approach that minimizes the black box problem and increases model- ing flexibility, while still providing an easy to use package in which highly capable models may be quickly and accu- rately built. This simulation approach utilizes SIMAN and ARENA. This paper includes a brief discussion of the simulation approach, a comparison of the proposed simula- tion and CORSIM simulation results for an intersection and an arterial, and a comparison of the proposed simula- tion control delay to delays collected for a twelve intersec- tion grid north of downtown Chicago. 1 INTRODUCTION Simulation is vital in the planning and development of al- most all transportation sectors. Isolated intersections, en- tire networks, airport landside and airside operations, freight movement, and passenger terminals: all of these features of a transportation system may be analyzed through simulation. List and Troutbeck (1999) describe four basic paradigms for simulation development: program code, flowcharts, pseudo code, and worksheets; although in practice simulation development usually involves a combi- nation of two or more of these approaches. In these para- digms simulations are constructed from the ground up, ad- dressing issues such as event-based vs. time-based simulation, distribution selection and implementation, un- derlying vehicle movement (i.e. car-following equations, Newtonian mechanics, acceleration / deceleration parame- ters, etc.), and selection of a programming language. Such simulation development contains several significant disad- vantages, particularly extensive training requirements and excessive development time and costs. To alleviate these disadvantages the practicing transportation community primarily relies on simulation packages. A few (of the many) examples of transportation simulation packages available include CORSIM, WATSim, INTEGRATION, VISSIM, and TEXAS. When a practitioner uses a simula- tion package, the simulation development effort has al- ready been completed. With the inclusion of graphical user interfaces, models are approaching plug and play capabilities, in which models may be quickly and eco- nomically constructed. While overcoming the advantages of simulation de- velopment these packages have disadvantages, most nota- bly the black box phenomenon and reduced modeling flexibility. An end user can enter data and receive results with little understanding of how the simulation operates and limited knowledge of the inherent assumptions. Also, a user is bound by the methods and assumptions of the given simulation package. It is virtually impossible for an end user to conceptualize, design, and develop a simulation for a situation beyond the bounds set by the simulation package developer. 2 PROPOSED SIMULATION MODELING APPROACH OBJECTIVES The model described in this paper lays the foundation for a transportation simulation approach that minimizes the black box problem and increases modeling flexibility while still providing an easy to use package in which highly ca- pable models may be quickly and accurately built. For this simulation modeling approach, SIMAN (Pedgen, Shannon, and Sadowski 1995), a general-purpose simulation lan- guage, and ARENA (Kelton, Sadowski, and Sadowski 1998), a hierarchical simulation-modeling tool that auto- mates the creation of SIMAN, were used. With SIMAN 1642