51 research outputs found
On Accommodating Flexible Spatial Dependence Structures in Unordered Multinomial Choice Models: Formulation and Application to Teenagers' Activity Participation
ABSTRACT The current paper proposes an approach to accommodate flexible spatial dependency structures in discrete choice models in general, and in unordered multinomial choice models in particular. The approach is applied to examine teenagers' participation in social and recreational activity episodes, a subject of considerable interest in the transportation, sociology, psychology, and adolescence development fields. The sample for the analysis is drawn from the 2000 San Francisco Bay Area Travel Survey (BATS) as well as other supplementary data sources. The analysis considers the effects of a variety of built environment and demographic variables on teenagers' activity behavior. In addition, spatial dependence effects (due to common unobserved residential neighborhood characteristics as well as diffusion/interaction effects) are accommodated. The variable effects indicate that parents' physical activity participation constitutes the most important factor influencing teenagers' physical activity participation levels, In addition, part-time student status, gender, and seasonal effects are also important determinants of teenagers' social-recreational activity participation. The analysis also finds strong spatial correlation effects in teenagers' activity participation behaviors
Factors Related to Accelerometer-determined Patterns of Physical Activity in Adults: The Houston TRAIN Study
Meeting U.S. Physical Activity (PA) Guidelines has health benefits. Yet, little is known about the factors related to changes in PA over time, particularly among minority populations. PURPOSE: To examine sociodemographic, PA preferences, and health factors related to accelerometer-derived patterns of 1-year PA change in the Houston Travel Related Activity in Neighborhoods (TRAIN) Study, a majority-minority cohort. METHODS: Participants wore an ActiGraph wGT3X-BT monitor and completed self-report surveys at baseline and follow-up. Valid wear time was defined as â„ 4 days, â„ 10 hrs/day. PA was stratified by meeting Guidelines using total MVPA, defined by Freedson. Four PA patterns were defined: (i) âmaintain highâ activity above Guidelines, (ii) âincreasedâ to meet Guidelines, (iii) âdecreasedâ from meet to not meet Guidelines, and (iv) âmaintained lowâ activity. Multinomial logistic regression was used to examine associations between studied factors and each PA pattern, with the âmaintain highâ group as referent. RESULTS: Complete data were available for 153 adults (19% maintained high activity, 8.5% increased, 13% decreased, 59.5% maintained low activity). Controlling for all variables, males (OR = 0.3, 95% CI = 0.1, 0.9) had lower odds of being in the âmaintain lowâ group. Blacks (vs. whites, OR = 18.8, 95% CI = 2.6, 275.0), those liking biking (vs. strongly liking, OR = 4.6, 95% CI = 1.3, 15.6), and older participants (vs. younger, on continuous scale, OR = 1.1, 95% CI = 1.0, 1.1) had higher odds of being in the âmaintain lowâ group. Factors directly associated with being in the âincreasedâ group were being black (vs. white, OR = 17.9, 95% CI = 1.3, 120.9), strong dislike for biking (vs. strongly liking OR = 25.2, 95% CI = 1.6, 401.3), and having more chronic diseases (vs. less, on continuous scale, 95% CI = 1.5, 11.7). Having low educational attainment (vs. high, OR = 0.04, 95% CI = 0.0, 0.9) was inversely associated with being in the âincreasedâ group. No studied factors were significantly associated with being in the âdecreasedâ group. CONCLUSION: PA patterns are dynamic and suggest that sociodemographic, PA preferences, and health factors relate to change patterns over time. Future studies should examine the role of these factors over longer follow-up periods, and consider these factors when designing interventions
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Flexible Spatial Dependence Structures for Unordered Multinomial Choice Models: Formulation and Application to Teenagersâ Activity Participation
At the time of publication I.N. Sener was at Texas Transportation Institute and C.R. Bhat was the University of Texas at Austin.The current paper proposes an approach to accommodate flexible spatial dependency structures in
discrete choice models in general, and in unordered multinomial choice models in particular. The
approach is applied to examine teenagersâ participation in social and recreational activity episodes, a
subject of considerable interest in the transportation, sociology, psychology, and adolescence
development fields. The sample for the analysis is drawn from the 2000 San Francisco Bay Area
Travel Survey (BATS) as well as other supplementary data sources. The analysis considers the
effects of a variety of built environment and demographic variables on teenagersâ activity behavior.
In addition, spatial dependence effects (due to common unobserved residential neighborhood
characteristics as well as diffusion/interaction effects) are accommodated. The variable effects
indicate that parentsâ physical activity participation constitutes the most important factor influencing
teenagersâ physical activity participation levels, In addition, part-time student status, gender, and
seasonal effects are also important determinants of teenagersâ social-recreational activity
participation. The analysis also finds strong spatial correlation effects in teenagersâ activity
participation behaviors.Civil, Architectural, and Environmental Engineerin
Modeling the Spatial and Temporal Dimensions of Recreational Activity Participation with a Focus on Physical Activities
At the time of publication I.N. Sener was at Texas Transportation Institute and C.R. Bhat was at the University of Texas at Austin.This study presents a unified framework to understand the weekday recreational activity
participation time-use of adults, with an emphasis on the time expended in physically active
recreation pursuits by location and by time-of-day. Such an analysis is important for a better
understanding of how individuals incorporate physical activity into their daily activities on a
typical weekday, and can inform the development of effective policy interventions to facilitate
physical activity. Furthermore, such a study of participation and time use in recreational activity
episodes contributes to activity-based travel demand modeling, since recreational activity
participation comprises a substantial share of individualsâ total non-work activity participation.
The methodology employed here is the multiple discrete continuous extreme value (MDCEV)
model, which provides a unified framework to explicitly and endogenously examine time use by
type, location, and timing. The data for the empirical analysis is drawn from the 2000 Bay Area
Travel Survey (BATS), supplemented with other secondary sources that provide information on
physical environment variables. To our knowledge, this is the first study to jointly address the
issues of âwhereâ, âwhenâ and âhow muchâ individuals choose to participate in âwhat type of
(recreational) activityâ.Civil, Architectural, and Environmental Engineerin
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Accommodating flexible spatial and social dependency structures in discrete choice models of activity-based travel demand modeling
textSpatial and social dependence shape human activity-travel pattern decisions and their antecedent choices. Although the transportation literature has long recognized the importance of considering spatial and social dependencies in modeling individualsâ choice behavior, there has been less research on techniques to accommodate these dependencies in discrete choice models, mainly because of the modeling complexities introduced by such interdependencies. The main goal of this dissertation, therefore, is to propose new modeling approaches for accommodating flexible spatial and social dependency structures in discrete choice models within the broader context of activity-based travel demand modeling. The primary objectives of this dissertation research are three-fold. The first objective is to develop a discrete choice modeling methodology that explicitly incorporates spatial dependency (or correlation) across location choice alternatives (whether the choice alternatives are contiguous or non-contiguous). This is achieved by incorporating flexible spatial correlations and patterns using a closed-form Generalized Extreme Value (GEV) structure. The second objective is to propose new approaches to accommodate spatial dependency (or correlation) across observational units for different aspatial discrete choice models, including binary choice and ordered-response choice models. This is achieved by adopting different copula-based methodologies, which offer flexible dependency structures to test for different forms of dependencies. Further, simple and practical approaches are proposed, obviating the need for any kind of simulation machinery and methods for estimation. Finally, the third objective is to formulate an enhanced methodology to capture the social dependency (or correlation) across observational units. In particular, a clustered copula-based approach is formulated to recognize the potential dependence due to cluster effects (such as family-related effects) in an ordered-response context. The proposed approaches are empirically applied in the context of both spatial and aspatial choice situations, including residential location and activity participation choices. In particular, the results show that ignoring spatial and social dependencies, when present, can lead to inconsistent and inefficient parameter estimates that, in turn, can result in misinformed policy actions and recommendations. The approaches proposed in this research are simple, flexible and easy-to-implement, applicable to data sets of any size, do not require any simulation machinery, and do not impose any restrictive assumptions on the dependency structure.Civil, Architectural, and Environmental Engineerin
On Jointly Analyzing the Physical Activity Participation Levels of Individuals in a Family Unit Using a Multivariate Copula Framework
At the time of publication Ipek N. Sener was at the Texas Transportation Institute, Naveen Eluru was at McGill University, and Chandra R. Bhat was at the University of Texas at Austin.The current paper focuses on analyzing and modeling the physical activity
participation levels (in terms of the number of daily âboutsâ or âepisodesâ of
physical activity during a weekend day) of all members of a family jointly.
Essentially, we consider a family as a âclusterâ of individuals whose physical
activity propensities may be affected by common household attributes (such as
household income and household structure) as well as unobserved family-related
factors (such as family life-style and health consciousness, and residential
location-related factors). The proposed copula-based clustered ordered-response
model structure allows the testing of various dependency forms among the
physical activity propensities of individuals of the same household (generated due
to the unobserved family-related factors), including non-linear and asymmetric
dependency forms. The proposed model system is applied to study physical
activity participations of individuals, using data drawn from the 2000 San
Francisco Bay Area Household Travel Survey (BATS). A number of individual
factors, physical environment factors, and social environment factors are
considered in the empirical analysis. The results indicate that reduced vehicle
ownership and increased bicycle ownership are important positive determinants ofweekend physical activity participation levels, though these results should be tempered by the possibility that individuals who are predisposed to physical activity may choose to own fewer motorized vehicles and more bicycles in the first place. Our results also suggest that policy interventions aimed at increasing childrenâs physical activity levels could potentially benefit from targeting entire family units rather than targeting only children. Finally, the results indicate strong and asymmetric dependence among the unobserved physical activity determinants of family members. In particular, the results show that unobserved factors (such as residence location-related constraints and family lifestyle preferences) result in individuals in a family having uniformly low physical activity, but there is less clustering of this kind at the high end of the physical activity propensity spectrum.Civil, Architectural, and Environmental Engineerin
On Jointly Analyzing the Physical Activity Participation Levels of Individuals in a Family Unit Using a Multivariate Copula Framework
At the time of publication Ipek N. Sener was at the Texas Transportation Institute, Naveen Eluru was at McGill University, and Chandra R. Bhat was at the University of Texas at Austin.The current paper focuses on analyzing and modeling the physical activity
participation levels (in terms of the number of daily âboutsâ or âepisodesâ of
physical activity during a weekend day) of all members of a family jointly.
Essentially, we consider a family as a âclusterâ of individuals whose physical
activity propensities may be affected by common household attributes (such as
household income and household structure) as well as unobserved family-related
factors (such as family life-style and health consciousness, and residential
location-related factors). The proposed copula-based clustered ordered-response
model structure allows the testing of various dependency forms among the
physical activity propensities of individuals of the same household (generated due
to the unobserved family-related factors), including non-linear and asymmetric
dependency forms. The proposed model system is applied to study physical
activity participations of individuals, using data drawn from the 2000 San
Francisco Bay Area Household Travel Survey (BATS). A number of individual
factors, physical environment factors, and social environment factors are
considered in the empirical analysis. The results indicate that reduced vehicle
ownership and increased bicycle ownership are important positive determinants ofweekend physical activity participation levels, though these results should be tempered by the possibility that individuals who are predisposed to physical activity may choose to own fewer motorized vehicles and more bicycles in the first place. Our results also suggest that policy interventions aimed at increasing childrenâs physical activity levels could potentially benefit from targeting entire family units rather than targeting only children. Finally, the results indicate strong and asymmetric dependence among the unobserved physical activity determinants of family members. In particular, the results show that unobserved factors (such as residence location-related constraints and family lifestyle preferences) result in individuals in a family having uniformly low physical activity, but there is less clustering of this kind at the high end of the physical activity propensity spectrum.Civil, Architectural, and Environmental Engineerin
Understanding Potential Exposure of Bicyclists on Roadways to Traffic-Related Air Pollution: Findings from El Paso, Texas, Using Strava Metro Data
As bicycling on roadways can cause adverse health effects, there is an urgent need to understand how bicycle routes expose bicyclists to traffic emissions. Limited resources for monitoring reveal that bicycle travel patterns may constrain such understanding at the network level. This study examined the potential exposure of bicyclists to traffic-related air pollution in El Paso, Texas, using Strava Metro data that revealed bicycle patterns across the city networks. An initial spatial mapping analysis was conducted to explore the spatial patterns of bicycling and traffic pollutant emission, followed by exploratory descriptive statistics. A spatial bicycle model was then developed to explore factors influencing bicycling activity in El Paso. Analysis results indicated significant associations between greater bicycle volume and both higher levels of particulate matter (PM2.5) emissions and more frequent bus services, implying adverse health concerns related to traffic-related air pollution. The results also indicated significant effects of various environmental characteristics (e.g., roadway, bicycle infrastructure, topography, and demographics) on bicycling. The findings encourage extending this study to provide guidance to bicyclists whose regular trips take place on heavily trafficked roads and during rush hours in this region and to evaluate the net health impacts of on-road bicycling for the general population
The effect of light rail transit on land-use development in a city without zoning
Light rail transit (LRT) has become a popular strategy to improve accessibility and mobility in the United States. It has also been touted as a tool to spur urban growth, higher-density development, and revitalization in large, auto-dependent cities like Houston, Texas. Although traditionally known as sprawling and highly auto-oriented, Houston has greatly expanded its light rail system in recent years. The city is also unique in that it is by far the largest city in the United States without zoning ordinances.
The city of Houston is used as a case study to examine land-use development around LRT stations. Analysis of parcel-level land-use data from 2005â2014 revealed a spike in commercial development along the original light rail corridor, approximately 4 to 10 years after its opening. Land-use development along the newer light rail corridors was more modest and not considerably different than the control corridors. Small changes in the levels of high-density residential housing and land-use mix near light rail stations indicated that efforts to encourage transit-oriented development have not yet had much effect
Planning for Bike Share Connectivity to Rail Transit
Bike sharing can play a role in providing access to transit stations and then to final destinations, but early implementation of these systems in North America has been opportunistic rather than strategic. This study evaluates local intermodal plan goals using trip data and associated infrastructure such as transit stops and bike share station locations in Austin, Texas, and Chicago, Illinois. Bike sharing use data from both cities suggest a weak relationship with existing rail stations that could be strengthened through collaborative, intermodal planning. The study suggests a planning framework and example language that could be tailored to help address the linkage between bike sharing and transit. Rather than an exhaustive study of the practice, this study provides evidence from these two cities that identify opportunities to improve intermodal planning. Cities that are planning or expanding a bike sharing system should consider carefully how to leverage this mode with existing modes of transport. Regardless of a cityâs status in implementing a bike sharing system, planners can leverage information on existing transport systems for planning at regional and local levels
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