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• 1. [Article] Issues in Trip Generation Methods for Transportation Impact Estimation of Land Use Development: A Review and Discussion of the State-of-the-Art Approaches

  As agencies develop more robust planning objectives for creating sustainable and livable communities, the research community has continued developing supportive tools and methods to provide more accurate ...

  Citation × Citation Citation Abstract Copy Title: Issues in Trip Generation Methods for Transportation Impact Estimation of Land Use Development: A Review and Discussion of the State-of-the-Art Approaches Author: Currans, Kristina Marie Year: 2017 As agencies develop more robust planning objectives for creating sustainable and livable communities, the research community has continued developing supportive tools and methods to provide more accurate and robust means for estimating transportation impacts for site-level development review. This paper is a review of the state-of-the-art trip generation methods for land use transportation impact estimation. First, it provides an overview of the more recent available and peer-reviewed estimation methods. Second, the authors offer a discussion of the successes of state-of-the-art approaches using common themes of research to identify corresponding consistency with theories of travel behavior and urban economics. These themes include: (a) the ability to estimate overall amounts of activity; (b) built environment and multimodal estimation; (c) socio-and economic demographics; (d) mixed and/or multiuse methods; and (e) land use (dis)aggregation. The main objective of this paper is to, throughout the discussion and conclusions, identify the largest and potentially problematic gaps in the state-of-the-art methods available for practice in order to allow researchers, agencies, and practitioners to both be aware of these limitations and forge forward new innovations to solve these on-going problems Title: Issues in Trip Generation Methods for Transportation Impact Estimation of Land Use Development: A Review and Discussion of the State-of-the-Art Approaches Author: Currans, Kristina Marie Year: 2017 As agencies develop more robust planning objectives for creating sustainable and livable communities, the research community has continued developing supportive tools and methods to provide more accurate and robust means for estimating transportation impacts for site-level development review. This paper is a review of the state-of-the-art trip generation methods for land use transportation impact estimation. First, it provides an overview of the more recent available and peer-reviewed estimation methods. Second, the authors offer a discussion of the successes of state-of-the-art approaches using common themes of research to identify corresponding consistency with theories of travel behavior and urban economics. These themes include: (a) the ability to estimate overall amounts of activity; (b) built environment and multimodal estimation; (c) socio-and economic demographics; (d) mixed and/or multiuse methods; and (e) land use (dis)aggregation. The main objective of this paper is to, throughout the discussion and conclusions, identify the largest and potentially problematic gaps in the state-of-the-art methods available for practice in order to allow researchers, agencies, and practitioners to both be aware of these limitations and forge forward new innovations to solve these on-going problems Close

• 2. [Article] Accessibility, Income, and Person Trip Generation: Multilevel Model of Activity at Food Retail Establishments in Portland, Oregon

  In the past decade, the methods for estimating multimodal transportation impacts of urban land use development have improved substantially. One assumption commonly made in these new methods is that overall ...

  Citation × Citation Citation Abstract Copy Title: Accessibility, Income, and Person Trip Generation: Multilevel Model of Activity at Food Retail Establishments in Portland, Oregon Author: Currans, Kristina Marie, Clifton, Kelly Year: 2017 In the past decade, the methods for estimating multimodal transportation impacts of urban land use development have improved substantially. One assumption commonly made in these new methods is that overall person-trip rates at similarly-sized establishments of the same land use do not vary across a region. This is an assumption of convenience to permit the adjustment of ITE Trip Generation vehicle trip rates for use in different urban environments. However, this assumption is inconsistent with theories of urban economics, which recognize that businesses pay a premium to locate in areas with high levels of accessibility to attract more customers. In addition, most transportation impact analyses have ignored income effects, even though socio-economics are a proven driver of travel behavior. To test this assumption and understand the effects of accessibility and income on levels of activity at the establishment level, we examine transaction counts for 97 grocery and convenience markets in Portland, Oregon. In a multilevel negative binomial regression, we test the relationship of regional accessibility, local accessibility, and income on weekly and daily transaction rates. While there was not enough evidence to suggest a significant relationship between accessibility and transaction rates, the results indicated a significant relationship with median income of the surrounding area. The implications point to the need to consider area-wide socio-demographics in site-level transportation impact analysis. The study also provides some important discussion about the use of transaction as a proxy for person-trip rates. Title: Accessibility, Income, and Person Trip Generation: Multilevel Model of Activity at Food Retail Establishments in Portland, Oregon Author: Currans, Kristina Marie, Clifton, Kelly Year: 2017 In the past decade, the methods for estimating multimodal transportation impacts of urban land use development have improved substantially. One assumption commonly made in these new methods is that overall person-trip rates at similarly-sized establishments of the same land use do not vary across a region. This is an assumption of convenience to permit the adjustment of ITE Trip Generation vehicle trip rates for use in different urban environments. However, this assumption is inconsistent with theories of urban economics, which recognize that businesses pay a premium to locate in areas with high levels of accessibility to attract more customers. In addition, most transportation impact analyses have ignored income effects, even though socio-economics are a proven driver of travel behavior. To test this assumption and understand the effects of accessibility and income on levels of activity at the establishment level, we examine transaction counts for 97 grocery and convenience markets in Portland, Oregon. In a multilevel negative binomial regression, we test the relationship of regional accessibility, local accessibility, and income on weekly and daily transaction rates. While there was not enough evidence to suggest a significant relationship between accessibility and transaction rates, the results indicated a significant relationship with median income of the surrounding area. The implications point to the need to consider area-wide socio-demographics in site-level transportation impact analysis. The study also provides some important discussion about the use of transaction as a proxy for person-trip rates. Close

• 3. [Article] Improving Trip Generation Methods for Livable Communities

  Recent efforts to improve trip generation data available for transportation impact analysis of new development include the collection of multimodal trip generation data, development of models that account ...

  Citation × Citation Citation Abstract Copy Title: Improving Trip Generation Methods for Livable Communities Author: Clifton, Kelly J., Larco, Nico, Currans, Kristina Marie, Wettach-Glosser, Jael Year: 2017 Recent efforts to improve trip generation data available for transportation impact analysis of new development include the collection of multimodal trip generation data, development of models that account for the built environment, and new recommendations for practice. Building on a long line of research on transportation and built environment, many studies have identified important features of the surrounding built environment that most impact trip rates and mode shares, building on a long line of research on transportation and the built environment. Despite these improvements in data and methods, less attention is placed on identifying the conditions of the site itself and the immediate surrounding environment that influence trip generation and mode choice. To fill this gap, this study builds upon previous work (Contextual Influences on Trip Generation (Project Number: OTREC 2011-407), 2012), re-examines the information collected in that study, and includes new site-level observations. The objective of this study is to examine establishment multimodal trip generation more closely from a finer-grained scale and identify site-level attributes of the built environment that help explain multimodal trip generation. From this, we have the additional objective of developing a framework for trip generation analysis that takes findings from this study into consideration. We placed emphasis on those sites in our previous study with a discord between the expected travel patterns, based upon the larger urban context and built environment of the site, and the observed. The research approach will make use of mixed methods. In addition to using archived data from the previous study, site visits provided direct observation of the overall performance of the site, including travel patterns on and around the site as well as specific site configuration, urban design details and traffic operations. The analysis of this combination of data provided a more complete picture of site-level trip generation and our findings highlight the influence of: people living nearby and using the site; the nature of the land use on the site; the development along arterial roadways; site permeability and access; and the local culture around walking and cycling. Finally, this report ends by reflecting on the numerous concerns identified from practice, the research findings from various recent studies, and the need for a sustainable process for evaluating the transportation impacts of new land development. We present a potential framework to advance the methods for how site plans fit into neighborhood and regional planning, using locally defined standards and goals. Here, we de-emphasize the site and its immediate environs as the primary (and only) scale of analysis and lessen the reliance on the problematic methodologies for estimating site-level travel demand. Rather, we argue that transportation impact analysis would benefit by first taking a district, neighborhood or area-wide approach with attention to the urban context—the built and social environment—where a site is located. At this larger scale, there is a better ability to understand the various elements that work together to shape travel demand and allows for a better assessment of how a specific site proposal will integrate into this larger context. This effort involves several faculty from across the country, including Kelly Clifton (PSU Engineering) and Nico Larco (UO Architecture) from our consortium and Susan Handy (UC Davis Environmental Studies) and Robert Schneider (UW Milwaukee Planning) as consultants/advisors. Title: Improving Trip Generation Methods for Livable Communities Author: Clifton, Kelly J., Larco, Nico, Currans, Kristina Marie, Wettach-Glosser, Jael Year: 2017 Recent efforts to improve trip generation data available for transportation impact analysis of new development include the collection of multimodal trip generation data, development of models that account for the built environment, and new recommendations for practice. Building on a long line of research on transportation and built environment, many studies have identified important features of the surrounding built environment that most impact trip rates and mode shares, building on a long line of research on transportation and the built environment. Despite these improvements in data and methods, less attention is placed on identifying the conditions of the site itself and the immediate surrounding environment that influence trip generation and mode choice. To fill this gap, this study builds upon previous work (Contextual Influences on Trip Generation (Project Number: OTREC 2011-407), 2012), re-examines the information collected in that study, and includes new site-level observations. The objective of this study is to examine establishment multimodal trip generation more closely from a finer-grained scale and identify site-level attributes of the built environment that help explain multimodal trip generation. From this, we have the additional objective of developing a framework for trip generation analysis that takes findings from this study into consideration. We placed emphasis on those sites in our previous study with a discord between the expected travel patterns, based upon the larger urban context and built environment of the site, and the observed. The research approach will make use of mixed methods. In addition to using archived data from the previous study, site visits provided direct observation of the overall performance of the site, including travel patterns on and around the site as well as specific site configuration, urban design details and traffic operations. The analysis of this combination of data provided a more complete picture of site-level trip generation and our findings highlight the influence of: people living nearby and using the site; the nature of the land use on the site; the development along arterial roadways; site permeability and access; and the local culture around walking and cycling. Finally, this report ends by reflecting on the numerous concerns identified from practice, the research findings from various recent studies, and the need for a sustainable process for evaluating the transportation impacts of new land development. We present a potential framework to advance the methods for how site plans fit into neighborhood and regional planning, using locally defined standards and goals. Here, we de-emphasize the site and its immediate environs as the primary (and only) scale of analysis and lessen the reliance on the problematic methodologies for estimating site-level travel demand. Rather, we argue that transportation impact analysis would benefit by first taking a district, neighborhood or area-wide approach with attention to the urban context—the built and social environment—where a site is located. At this larger scale, there is a better ability to understand the various elements that work together to shape travel demand and allows for a better assessment of how a specific site proposal will integrate into this larger context. This effort involves several faculty from across the country, including Kelly Clifton (PSU Engineering) and Nico Larco (UO Architecture) from our consortium and Susan Handy (UC Davis Environmental Studies) and Robert Schneider (UW Milwaukee Planning) as consultants/advisors. Close