This study developed a validation procedure for a dynamic traffic assignment–based mesoscopic simulator and identified its relevant data requirements. Model inconsistencies at the network level can be detected through route-based validation with probe vehicle travel time data. Simultaneously, link-based validation uses point detector–based volume and speed data. A procedure for filtering the validation data set to make it consistent and comparable with the simulation results is outlined in the paper. Two assignment methods were tested with a detailed validation data set through a case study. The no-diversion assignment approach yielded higher travel time than the field-observed average time. In contrast, simulated travel time with the optimal diversion method implied a more rational behavior by drivers than was observed in the field, along with more diversion of trips on arterial routes in the vicinity of a work zone. Finally, a link-based performance comparison revealed worse queue spillback effects on the upstream links of the work zone than in reality.