The Two-Fluid traffic model is a tool used to measure the quality of service in city traffic networks. The model has been calibrated for the central business district of Roanoke, Virginia and the results have been compared to those from various other cities around the world. In addition, the sensitivity of the Two-Fluid model parameters has been studied for different unit trip lengths used in calibration for the Roanoke CBD. The three-unit trip lengths tested were 1-mile, 2-mile, and 3-mile. Statistical analyses led to the conclusion that the model parameters are not significantly different for different trip lengths. Furthermore, parameter sensitivity was also established for three types of driver behavior, specifically, "aggressive," "normal," and "conservative." The two-fluid trends showed that the two-fluid curve corresponding to the aggressive driver fell below those of the normal and conservative drivers for off-peak traffic conditions but began to approach the normal trend during peak period. On the other hand, the conservative trend continuously maintained higher trip time values for any given stop time, as compared to the other two trends. This implies that aggressive driving behavior can decrease travel times during off-peak conditions, but has little effect during peak periods, where surrounding traffic does not allow excessive speed or lane changing. / M.S.