To improve methods of evaluating the benefits from investments in the transport infrastructure, this paper attempts to develop a method for capturing changes in variations in travel time expenditure and shows empirical results from data from the German Mobility Panel, a multiday and multiperiod panel survey. The proposed methodology can simultaneously and explicitly deal with changes and variations. The empirical analysis indicates that over time, travel time expenditures become more dependent on situational attributes than on individual or household attributes; such dependence implies that travel time expenditures change toward diversification and that longer periods of behavioral observation to describe people's travel time expenditures become more important. The results also imply that understanding of the dynamic aspects of behavior is still important and remains a challenging issue to be revisited, not only for improving forecasting models but also for reconsidering the benefits from investment in transportation infrastructure.