Browsing by Subject "travel demand"
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Item Accommodating Multiple Constraints in the Multiple Discrete-Continuous Extreme Value (MDCEV) Choice Model(Transportation Research Board of the National Academies, 2012) Castro, Marisol; Bhat, Chandra R.; Pendyala, Ram M.; Jara-Diaz, Sergio R.Multiple-discrete continuous choice models formulated and applied in recent years consider a single linear resource constraint, which, when combined with consumer preferences, determines the optimal consumption point. However, in reality, consumers face multiple resource constraints such as those associated with time, money, and capacity. Ignoring such multiple constraints and instead using a single constraint can, and in general will, lead to poor data fit and inconsistent preference estimation, which can then have a serious negative downstream effect on forecasting and welfare/policy analysis. In this paper, we extend the multiple-discrete continuous extreme value (MDCEV) model to accommodate multiple constraints. The formulation uses a flexible and general utility function form, and is applicable to the case of complete demand systems as well as incomplete demand systems. The proposed MC-MDCEV model is applied to time-use decisions, where individuals are assumed to maximize their utility from time-use in one or more activities subject to monetary and time availability constraints. The sample for the empirical exercise is generated by combining time-use information from the 2008 American Time Use Survey and expenditure records from the 2008 U.S. Consumer Expenditure Survey. The estimation results show that preferences can get severely mis-estimated, and the data fit can degrade substantially, when only a subset of active resource constraints is used.Item Joint Model of Participation in Nonwork Activities and Time-of-Day Choice Set Formation for Workers(National Academy of Sciences, 2011) Castro, Marisol; Eluru, Naveen; Bhat, Chandra R.; Pendyala, Ram M.Non-work activity and travel participation is an important component of overall travel demand that is complex to model as the greater degrees of flexibility associated with such travel induces larger variability and randomness in this behavior. This paper aims to offer a framework for modeling the participation in and travel mileage allocated to non-work activities during various time periods of the day for workers. Five time-of-day blocks are defined for workers based on the period of the day in relation to the work schedule. Individuals can choose to pursue non-work activities in one or multiple time blocks and travel miles to accomplish the activities. A multiple discrete-continuous extreme value (MCDEV) modeling approach is employed to model this phenomenon. A unique element of the paper is the addition of a latent choice set generation model as a first component in the model system. This choice set generation model can be used to determine the set of time-of-day periods that each individual will consider for the pursuit of non-work activities, while recognizing the fact that the consideration choice set is not explicitly observed (and is therefore latent) by the analyst. Thus, the model system presented in this paper is capable of modeling non-work activity engagement and associated travel mileage by time-ofday period while incorporating varying choice sets across individuals. The two-component model system is applied to a survey sample drawn from the San Francisco area of the United States, and shown to perform substantially better than a pure MDCEV model that assumes a constant choice set across the sample.