Date of Completion


Embargo Period



Transportation planning, travel behavior, activity based modeling, time allocation, statistics, econometric, latent variable, multiple discrete continuous choices

Major Advisor

Karthik Konduri

Associate Advisor

Nicholas Lownes

Associate Advisor

John Ivan

Associate Advisor

Nalini Ravishanker

Associate Advisor

Naveen Eluru

Field of Study

Civil Engineering


Doctor of Philosophy

Open Access

Open Access


Historically, transportation planning relied on aggregate, trip-based procedures, namely, four-step modeling, for modeling travel demand. The aggregate approaches served well when the capacity oriented policies were of primary interest. However, in the last few decades, with the growing demand for travel and the increasing externalities (e.g. congestion, energy implications, pollution), there is a widespread acknowledgement that capacity oriented approach to transportation planning is unsustainable. Instead, the focus of the transportation planners has shifted towards sustainable demand management strategies wherein the idea is to alter existing behaviors and promote new behaviors such that demand for travel can be met while also reducing the externalities of travel choices. This swing in policy necessitated a shift to disaggregate, activity-based approaches for analyzing travel behavior. One of the fundamental differences between the trip- and activity-based travel behavior analyses lies in the treatment of time. In the trip-based approach, time is merely treated as a cost of accessing activity opportunities separated in space. On the other hand, activity-based approach, dwells on the understanding of time expenditure behavior of individual including how, where, and with whom individuals spend their time. Subsequently, trips are organically derived from activity engagement behavior.

As can be seen, a robust understanding of time engagement decision of individuals forms the backbone of current day transportation planning process. Individuals’ allocation of time has intrigued researchers not only from the field of transportation, but also from various other disciplines such as economics, philosophy, psychology, and sociology.

The overarching objective of this dissertation is to advance the time engagement research with the goal of enriching the state-of-the-art activity-based travel analysis techniques. To this end, the contributions of the research are twofold. First, on the substantive side, the dissertation utilizes a multidisciplinary approach by incorporating theories from various disciplines such as economics, and psychology to further our understanding of the time engagement decisions of individuals. Second, on the methodological side, the dissertation develops, and applies advanced econometric methodologies to characterize the time engagement behavior of the individuals. The substantive and methodological findings allowed for an enriched formulation of time engagement in activity-based travel behavior models.