A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item UNDERSTANDING AND MODELLING TIME USE, WELL BEING AND DYNAMICS IN ACTIVITY-TRAVEL BEHAVIOR: A CHOICE BASED APPROACH(2018) Dong, Han; Cirillo, Cinzia; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Understanding the determinants of activity and travel related choices is critical for policy-makers, planners and engineers who are in charge of the management and design of large scale transportation systems. These systems, and their externalities, are interwoven with human actions and communities’ evolution. Traditionally, individual decision-making and travel behaviour studies are based on random utility models (RUM) and discrete choice analysis. To extend the ability of modellers to represent and forecast complex travel behaviour, this dissertation expands existing models to accommodate the influence of variables other than the traditional socio-demographics or level of service variables. In this thesis, technology innovations, psychological factors, and perceptions of future uncertainty are integrated into the classical RUMs and their effects on activity-travel decision making are investigated. Technology innovations, such as telecommunication, online communities and entertainment, release individual’s time and space constraints. They also modify people’s activity and travel choices. An integrated discrete-continuous RUM is proposed to study individuals’ participation in leisure activities, which is an important component of activity scheduling analysis and tour/trip formation. Leisure alternatives considered include: computer/internet related activity, in-home activity, and out-of-home activity. Compared to previous discrete-continuous models, interdependence among activities and the related time usage is explored using a modelling structure that accommodate full correlation among decision variables of different types. Standard random utility models are extended by including attitudes and perceptions as latent variables; these constructs are expected to enhance the behavioural representation of the choice process. A simultaneous structural model is proposed to represent the mutual effects existing between psychological factors and activity choices. Biases due to endogeneity in psychological factors and activity choices are taken into consideration in the model. To further extend the behavioural realism of our model, this thesis proposes a new simultaneous equation model formulation that links psychological indicators to activity participation and time use decisions. Unlike previous studies, the proposed method allows the psychological factors to be correlated with time use decisions and serve as an attribute in time use choice model. A new iterative simulated maximization estimation method is also proposed to accommodate possible endogeneity bias in the model system. A simulation experiment shows that the estimation method produces consistent and unbiased estimation results. Moreover, a real case study is also implemented in the context of participation in leisure activities, linking emotions, activity involvement and time use. After exploring individual’s decisions on activity and time use choices, a dynamic discrete choice model framework is proposed to accommodate stochasticity in individual behaviour over time. Following previous studies, activity patterns are decomposed into tour and stop sequences. Accordingly, a tour choice model and a stop choice model are jointly formulated under a unified framework with a hierarchical structure where stop choices are assumed to be conditional on tour choices. The results indicate that individuals are sensitive to current and future changes in travel and activity characteristics and that a dynamic formulation better represents multi-day travel behaviour.Item Negative Construction Sectors That Inflate Gross Domestic Product: An Economic Case Study of Seattle Commercial Construction(2014) Christianson, Jeffrey James; Cui, Qingbin; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Gross Domestic Product (GDP) was created as a way to measure US production of products and services. GDP was not intended to guide policy making or as an indicator of the country's welfare. The commercial construction sectors of asbestos abatement, soil remediation, and building demolition are tangential to the actual cost of constructing a building and the country would be better off if these construction sectors were not necessary, even at the jeopardy of a reduced GDP. This thesis examines the specific costs of these construction sectors in Seattle commercial construction industry and determines that 1.66 percent of a Seattle commercial construction project's cost is spent on asbestos abatement, soil remediation, and building demolition. This research challenges the use of GDP and emphasizes the need for a different means to measure economic progress in consideration of the incurred environmental and social costs in the production of products and services.Item DYNAMIC DISCRETE CHOICE MODELS FOR CAR OWNERSHIP MODELING(2011) XU, RENTING; CIRILLO, CINZIA; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)With the continuous and rapid changes in modern societies, such as the introduction of advanced technologies, aggressive marketing strategies and innovative policies, it is more and more recognized by researchers in various disciplines from social science to economics that choice situations take place in a dynamic environment and that strong interdependencies exist among decisions made at different points in time. The increasing concerns about climate change, the development of high-tech vehicles, and the extensive applications of demand models in economics and transportation areas motivate this research on vehicle ownership based on disaggregate discrete choices. Over the next five to ten years, dramatic changes in the automotive marketplace are expected to occur and new opportunities might arise. Therefore, a methodology to model dynamic vehicle ownership choices is formulated and implemented in this dissertation for short and medium-term planning. In the proposed dynamic model framework, the car ownership problem is described as a regenerative optimal stopping problem; when a purchase is made, the current vehicle state (vehicle age, mileage driven, etc.) is regenerated. The model allows the estimation of the probability of buying a new vehicle or postponing this decision; if the decision to buy is made, the model further investigates the vehicle type choices. Dynamic models explicitly account for consumers' expectations of future vehicle quality or market evolution, arising endogenously from their purchase decisions. Both static and dynamic formulations are applied first to simulated data in order to test the ability to recover the true underlying parameters of the synthetic population. Results obtained attest that the dynamic model outperforms the static MNL in terms of goodness of fit, parameters bias and predictive power. In particular, it is found that MNL captures the general trends in choice probabilities, but fails to recover peaks in demand and behavioral changes due to rapidly evolving external conditions. The extension to a real case study required a data collection effort. A preliminary pilot survey was designed and executed in the State of Maryland in fall 2010; the survey was self-administrated and web-based. Choices were made under the hypothesis that an interval time period of six months passed from a decision to the successive decision and choices over a hypothetical time period of six years were recorded. Finally, the application of dynamic discrete choice models to vehicle ownership decisions in the context of the introduction of new technology is proposed. Results from the real case study confirm our initial expectations, as the model fit is significantly superior to the fit of the static model.