Browsing by Subject "activity-travel behavior"
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Item An analysis of the impact of information and communication technologies on non-maintenance shopping activities(Elsevier, 2003) Bhat, Chandra R.; Sivakumar, Aruna; Axhausen, Kay W.This paper examines the use and travel impacts of two forms of Information and Communication Technologies (ICTs): mobile telephones and computers. The travel impacts are examined in the context of participation in out-of-home non-maintenance shopping activities over a multiweek period through the modeling of the duration between successive shopping activity participations. The empirical analysis uses a continuous six-week travel survey collected in the cities of Halle and Karlsruhe in Germany in the Fall of 1999. The results indicate that the effects of ICTs on activity-travel patterns are mediated by individual sociodemographic and locational factors, as well as by unobserved individual characteristics. The results also show that the substitution between mobile phone use and shopping travel is grossly underestimated if the effects of common unobserved factors affecting mobile phone use and shopping travel are not considered. In addition, there is quite substantial intra-individual variation in intershopping duration.Item An Analysis of Weekly Out-of-Home Discretionary Activity Participation and Time-Use Behavior(Springer, 2009) Spissu, Erika; Pinjari, Abdul R.; Bhat, Chandra R.; Pendyala, Ram M.; Axhausen, Kay W.Activity-travel behavior research has hitherto focused on the modeling and understanding of daily time use and activity patterns and resulting travel demand. In this particular paper, an analysis and modeling of weekly activity-travel behavior is presented using a unique multi-week activity-travel behavior data set collected in and around Zurich, Switzerland. The paper focuses on six categories of discretionary activity participation to understand the determinants of, and the inter-personal and intra-personal variability in, weekly activity engagement at a detailed level. A panel version of the Mixed Multiple Discrete Continuous Extreme Value model (MMDCEV) that explicitly accounts for the panel (or repeated-observations) nature of the multi-week activity-travel behavior data set is developed and estimated on the data set. The model also controls for individual-level unobserved factors that lead to correlations in activity engagement preferences across different activity types. To our knowledge, this is the first formulation and application of a panel MMDCEV structure in the econometric literature. The analysis suggests the high prevalence of intra-personal variability in discretionary activity engagement over a multi-week period along with inter-personal variability that is typically considered in activitytravel modeling. In addition, the panel MMDCEV model helped identify the observed socioeconomic factors and unobserved individual specific factors that contribute to variability in multi-week discretionary activity participation.Item A comprehensive activity-travel pattern modeling system for non-workers with empirical focus on the organization of activity episodes(Transportation Research Board of the National Academies, 2002) Bhat, Chandra R.; Misra, RajulThis paper proposes a comprehensive continuous-time framework for representation and analysis of the activity-travel choices of non-workers. The paper also presents econometric formulations for components of the comprehensive framework that focus on the overall organization of activities (including number and type of activities, and activity sequencing) in the non-worker’s daily activity-travel pattern. The paper concludes with an empirical analysis using activity-travel data from the 1990 San Francisco Bay Area travel diary survey. A companion paper being prepared by the authors discusses the econometric formulations and associated empirical results for components of the overall framework that address the temporal and spatial attributes of the daily activity-travel pattern.Item An Exploration of the Relationship Between Timing and Duration of Maintenance Activities(Springer, 2004) Pendyala, Ram M.; Bhat, Chandra R.The timing and duration of an activity episode are two important temporal aspects of activity travel behavior. Understanding the causal relationship between these two variables would be useful in the development of activity-based travel demand modeling systems. This paper investigates the relationship between these two variables by considering two different causal structures - one structure in which time-of-day choice is determined first and influences duration and a second structure in which activity duration is determined first and affects time-of-day choice. These two structures are estimated within a discrete-continuous simultaneous equations framework employing a full-information maximum likelihood methodology that allows error covariance. The estimation is performed separately for commuter and non-commuter samples drawn from a 1996 household travel survey data set from the Tampa Bay area in Florida. The results of the model estimation effort show that the causal structure in which activity duration precedes or affects activity timing (time of day choice) performs better for the non-commuter sample. For the commuter sample, the findings were less conclusive with both causal structures offering equally good statistical measures of fit. In addition, for the commuter sample, all error correlations were found to be zero. These two findings suggest that time of day choice and activity episode duration are only loosely related for the commuter sample, possibly due to the relatively non-discretionary and inflexible work activity and travel.Item An exploratory analysis of fixed commitments in individual activity-travel patterns(Transportation Research Board of the National Academies, 2003) Frusti, Teresa; Bhat, Chandra R.; Axhausen, Kay W.This study examines the presence of fixed commitments in the activity-travel patterns of individuals. Data obtained from a 6-week travel diary survey undertaken in Germany is used in the empirical analysis. The results provide several important insights into the determinants of fixed commitments.Item Intershopping Duration: An Analysis Using Multiweek Data(Elsevier, 2004) Bhat, Chandra R.; Frusti, Teresa; Zhao, Huimin; Schonfelder, Stefan; Axhausen Kay W.This study examines the rhythms in the shopping activity participation of individuals over a multiweek period by modeling the duration between successive shopping participations. A hazard based duration model is used to model intershopping duration, and a latent segmentation method is applied to distinguish between erratic shoppers and regular shoppers. The paper applies the methodology to examine the regularity and frequency of shopping behavior of individuals using a continuous six-week travel survey collected in the cities of Halle and Karlsruhe in Germany in the fall of 1999. The empirical results underscore the need to adopt a flexible hazard model form for analyzing intershopping durations. The results also provide important insights into the determinants of the regularity and frequency of individuals' shopping activity participation behavior.Item A Joint Household Level Analysis of Work Arrangement Choices of Individuals(Transportation Research Board of the National Academies, 2012) Khan, Mubassira; Paleti, Rajesh; Bhat, Chandra R.; Pendyala, Ram M.This paper presents a comprehensive multi-dimensional multivariate binary probit model system capable of simultaneously representing multiple aspects of individual work arrangement decisions, while also accounting for interactions among household members in individual employment related choices. The model system is estimated on a survey sample drawn from the San Francisco Bay Area where a rich set of accessibility measures is available to account for built environment influences on work related decisions. Model results show that a host of demographic, socio-economic, built environment, and attitudinal variables influence individual choices regarding work arrangements; more importantly, the model shows that there is considerable interaction among household members in matters related to employment. The model system can be used to predict employment choices of individuals within larger microsimulation model systems of activity-travel demand.Item A joint tour-based model of tour complexity, passenger accompaniment, vehicle type choice, and tour length(2011-08-01) Paleti, Rajesh; Pendyala, Ram M.; Bhat, Chandra R.; Konduri, Karthik C.Tour-based model systems are increasingly being deployed to microsimulate daily activity-travel patterns of individuals. There are a host of tour attributes of interest that are modeled within these systems. However, a dimension that is often missed is that of vehicle type choice, a variable of considerable importance in the energy consumption and emissions estimation arena. Another issue that arises is that most tour attributes are modeled independently or sequentially with loose coupling across the models, thus ignoring important endogeneity effects that may exist across multiple tour dimensions. This paper considers four key dimensions of tours – tour complexity, passenger accompaniment, vehicle type choice, and tour length – with a view to developing a joint simultaneous equations model system of tour choices while accounting for the presence of correlated unobserved attributes affecting multiple dimensions through appropriate error covariance structures. The paper makes an important methodological contribution by describing and formulating a multi-dimensional joint choice model system capable of accommodating a variety of endogenous variable types (discrete and continuous). The paper makes an important empirical contribution by providing evidence on the nature of the relationships among these tour dimensions of interest within the context of a joint model. The model system is estimated on a sample of tours from the 2009 National Household Travel Survey of the United States. In general, it is found that there is significant evidence of correlated unobserved factors across these tour dimensions and that vehicle type choice affects tour length, a finding that could have important policy implications.