Browsing by Subject "travel behavior"
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Item Connecting Land Use and Transportation Toward Sustainable Development: A Case Study of Houston-Galveston Metropolitan Area(2011-02-22) Lee, Jae SuHow do land use characteristics affect individual and household travel behavior in a regional context? Can the investigation justify the land use policies to reduce automobile dependence and achieve the goals of sustainable development in the metropolitan areas? Previous research enhanced our understanding of the connections between land use and travel behavior. It also provided implications for managing automobile-dependent travel behavior. However, there are questions still left unanswered about the causal connections between them, and the effectiveness of the land use policies to manage travel demand. To address the issues, attention is focused on the effects of land use measures on travel behavior outcomes from different modeling perspectives. The travel demand modeling explores the associations between land use and travel behavior. In addition, the causal modeling helps clarify the causal connections between them. It includes the structural equation models (SEMs) and the directed acyclic graphs (DAGs). The study focuses on six counties of the Houston-Galveston Area Council (HGAC) area. Travel behavior outcomes contain individual mode choice, household automobile trip generation and household total vehicle miles traveled (VMT). Three dimensions (i.e., density, diversity and design) of six land use measures are considered, which are computed using quarter-mile buffers for both trip origins and destinations. Different travel outcomes and modeling strategies are examined for different travel purposes. The significance of land use measures in affecting travel behavior is found to be evident, while varying to a certain degree according to trip purposes, travel outcomes and methodologies. For individual model choice, multinomial logit (MNL) models, the SEMs and the DAGs for different trip purposes support the hypothesis that land use measures directly affect individual mode choice behavior when other factors are kept constant. There is also evidence from causal models that land use factors indirectly influence it through travel time. For household automobile trip generation, there is no evidence to assert that land use measures at origin significantly affect household automobile trip rates when travel cost and socioeconomic variables are controlled. However, it is confirmed that land use measures have indirect causal connections with automobile trips through travel costs for all trip purposes. For household total VMT, it is found that land use patterns around residential locations are not only significantly associated, but also causally connected with household VMT. To summarize, compact development with high density and improved network design generally contribute to the reduction in automobile dependent travel patterns in the HGAC region.Item The correlational and causal investigation into the land use-transportation relationships: evidence from the Dallas-Fort Worth metropolitan area(Texas A&M University, 2006-10-30) Lee, SangkugThe role of land-use and related policies in reducing automobile dependence has been the subject of heated policy debate for over two decades. Previous research has shed light on the correlations between land-use and travel. Yet a crucial knowledge gap still exists in establishing causality between the two. Do changes in land-use characteristics cause behavioral changes in individuals?????? decisions on what transportation means to use for travel? How does land-use as a contextual factor shape the decision process and outcome of trip frequency and travel mode choice? These questions remain largely unanswered. Attempting to fill the gap, this study applied the directed acyclic graphs method to identify the causal relationship between land-use and travel in the 9-county Dallas- Fort Worth (D-FW) metropolitan area. The logit captivity (LC) model, an extension to the conventional multinomial logit, was utilized to capture the contribution of land-use in affecting individuals?????? decisions on travel mode choice. All the data for this study were obtained from the North Central Texas Council of Governments (NCTCOG). Evidence from the D-FW region confirms to a certain extent the causal effects of land-use on travel. For work trips, increases in regional accessibility, job density and share of commercial land-use reduce the use of automobiles. Higher regional accessibility, however, causes households to generate automobile trips and thus leads to the increase in vehicle miles of travel (VMT). For non-work trips, population density, job density and regional accessibility are direct causes of the choice of automobile, while only regional accessibility is causally connected to reducing automobile trips and VMT. The logit captivity model results indicate that land-use contributes to captive-driving choices for home-based work trips. Lack of land-use mix at trip origins increases the probabilities of trip-makers being captive to the automobile from 0.06% to 5.62% for driving-alone and from 0.38% to 3.55% for shared-ride.Item Validating the Relationship Between Urban Form and Travel Behavior with Vehicle Miles Travelled(2010-01-14) Kakumani, RajaneshThe validity of the influence of urban form on travel behavior has been a topic of interest in travel behavior research. Empirical research shows that urban form influences travel behavior causing less travel impacts. However, according to the conventional travel impact assessment following the ITE?s (Institute of Transportation Engineers) Trip Generation Handbook, developments with higher levels of urban form measures will generate a greater travel impacts because they generate higher number of trips. The ITE Trip Generation Handbook is typically used as a guideline to estimate the number of trips generated by a development. The hypothesis made in the present research is that a development defined with higher levels of land use mix, street connectivity and residential density will generate a higher number of trips because of the greater accessibility but they will be shorter in length. Therefore, the effective distance travelled will be less even though higher numbers of trips are generated. Considering the distance travelled on a roadway will be an appropriate unit for measuring the travel impacts, the research argues that VMT (Vehicle Miles Travelled) can be a better measurement unit than the number of trips to validate the influence of urban form on travel behavior.