The validity and usefulness of system simulation has been well-established for decades in areas such as computer and communications systems, general manufacturing systems, and military systems along with many other areas. Recent years have seen the technique become entrenched in specific areas such as automotive manufacturing, semiconductor fabrication, and automated warehouse design.Transportation simulation also has a long history as evidenced by publication of numerous transportation simulation papers in the Winter Simulation Conference Proceedings and other publications over the years. During the past few years the number of transportation simulation applications presented at WSC has increased, to the point that in WSC'98 for the first time there is an entire track -24 presentations organized into eight sessions along with this panel sessiondevoted to transportation simulation applications.Is transportation poised to be the next big growth area for discrete-event simulation? Is it already a major area, left relatively unnoticed over the years due to the number of different application subareas? Is the growth already happening? What are the opportunities, and what are the barriers? This panel will address these and other questions. Key challenges in this simulation effort were: