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• 1. [Article] Contextual Influences on Trip Generation

  There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE ...

  Citation × Citation Citation Abstract Copy Title: Contextual Influences on Trip Generation Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2012 There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE rates represent travel behavior for development in single lots and uses, primarily measured in low-density suburban areas. Despite evidence that a more compact urban form, access to transit and a greater mix of uses generates fewer and shorter vehicle trips, local governments are often compelled to use current ITE trip generation rates to evaluate transportation impacts and calculate transportation system development charges (TSDCs). This is due to: a) the expense of collecting local data, b) lack of alternative sources of information, c) the strong industry bias toward using ITE published rates and d) the absence of a empirically tested methodology for adjusting those rates for development occurring in different land use and transportation contexts. Compounding these challenges, cities in Oregon are required to demonstrate that planning and zoning changes will not degrade the performance of state-owned transportation facilities compared to the levels of service documented in the Regional Transportation Plan under the Oregon Transportation Planning Rule, section -0060, and Oregon Highway Plan, Policy 1.F.6. These requirements can conflict with regional policies in Metro's 2040 Growth Concept that call for development of mixed-use centers and corridors to support jobs and freight reliability, a compact urban form and leverage transportation investments such as high capacity transit. Thus, there are gaps in the understanding about how best to evaluate, mitigate and plan for growth under these conditions. This research proposes to develop multi-modal trip generation rates that better reflect the relationship between land use, transportation and travel demand for specific land use types located in various urban settings. The project aims to collect local data (using multi-modal counts and establishment surveys) on a few specific land uses (deemed most problematic to estimate demand and occurring across the spectrum of urban conditions) to develop trip generation rates that are sensitive to demographic, land use and transportation contexts. These new trip rates will be compared to the ITE rates for the same land use category and a methodology for adjusting the ITE rates will be developed. This adjustment methodology will be validated, using additional data collected in this research. The research will be documented and made available to local partners and disseminated widely to reach out to other communities across the country. The research conducted for this project would account for how the built environment (e.g., both land use and transportation) influences travel behavior (number of trips, trip length, mode choice), and determine trip rates that reflect the entire activity spectrum of different development/place typologies. This is extremely important in determining the impact of different development types on the transportation system to: 1) avoid over-planning the system for the surrounding land uses; (2) suggest strategies and investment priorities to encourage more compact, mixed-use areas with more transportation choices and 3) avoid creating regulatory and/or financial barriers to compact form envisioned by local, regional and statewide plans (i.e. uniform TSDCs can result in lower impact development paying the same rates, and thus subsidizing development with higher impact costs to the transportation system). The documentation of the findings and methodology will be applicable to current and future growth and be transferable to other communities, locally and nationally, beyond the Portland region. Title: Contextual Influences on Trip Generation Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2012 There is national interest in building data that expands upon the existing Institute of Transportation Engineers (ITE) trip generation rates to include sites located in a multi-modal context. Current ITE rates represent travel behavior for development in single lots and uses, primarily measured in low-density suburban areas. Despite evidence that a more compact urban form, access to transit and a greater mix of uses generates fewer and shorter vehicle trips, local governments are often compelled to use current ITE trip generation rates to evaluate transportation impacts and calculate transportation system development charges (TSDCs). This is due to: a) the expense of collecting local data, b) lack of alternative sources of information, c) the strong industry bias toward using ITE published rates and d) the absence of a empirically tested methodology for adjusting those rates for development occurring in different land use and transportation contexts. Compounding these challenges, cities in Oregon are required to demonstrate that planning and zoning changes will not degrade the performance of state-owned transportation facilities compared to the levels of service documented in the Regional Transportation Plan under the Oregon Transportation Planning Rule, section -0060, and Oregon Highway Plan, Policy 1.F.6. These requirements can conflict with regional policies in Metro's 2040 Growth Concept that call for development of mixed-use centers and corridors to support jobs and freight reliability, a compact urban form and leverage transportation investments such as high capacity transit. Thus, there are gaps in the understanding about how best to evaluate, mitigate and plan for growth under these conditions. This research proposes to develop multi-modal trip generation rates that better reflect the relationship between land use, transportation and travel demand for specific land use types located in various urban settings. The project aims to collect local data (using multi-modal counts and establishment surveys) on a few specific land uses (deemed most problematic to estimate demand and occurring across the spectrum of urban conditions) to develop trip generation rates that are sensitive to demographic, land use and transportation contexts. These new trip rates will be compared to the ITE rates for the same land use category and a methodology for adjusting the ITE rates will be developed. This adjustment methodology will be validated, using additional data collected in this research. The research will be documented and made available to local partners and disseminated widely to reach out to other communities across the country. The research conducted for this project would account for how the built environment (e.g., both land use and transportation) influences travel behavior (number of trips, trip length, mode choice), and determine trip rates that reflect the entire activity spectrum of different development/place typologies. This is extremely important in determining the impact of different development types on the transportation system to: 1) avoid over-planning the system for the surrounding land uses; (2) suggest strategies and investment priorities to encourage more compact, mixed-use areas with more transportation choices and 3) avoid creating regulatory and/or financial barriers to compact form envisioned by local, regional and statewide plans (i.e. uniform TSDCs can result in lower impact development paying the same rates, and thus subsidizing development with higher impact costs to the transportation system). The documentation of the findings and methodology will be applicable to current and future growth and be transferable to other communities, locally and nationally, beyond the Portland region. Close

• 2. [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

• 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

• 4. [Article] Adjusting ITE’s Trip Generation Handbook for Urban Context

  This study examines the ways in which urban context affects vehicle trip generation rates across three land uses. An intercept travel survey was administered at 78 establishments (high-turnover restaurants, ...

  Citation × Citation Citation Abstract Copy Title: Adjusting ITE’s Trip Generation Handbook for Urban Context Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2015 This study examines the ways in which urban context affects vehicle trip generation rates across three land uses. An intercept travel survey was administered at 78 establishments (high-turnover restaurants, convenience markets, and drinking places) in the Portland, Oregon, region during 2011. This approach was developed to adjust the Institute of Transportation Engineers (ITE) Trip Generation Handbook vehicle trip rates based on built environment characteristics where the establishments were located. A number of policy-relevant built environment measures were used to estimate a set of nine models predicting an adjustment to ITE trip rates. Each model was estimated as a single measure: activity density, number of transit corridors, number of high-frequency bus lines, employment density, lot coverage, length of bicycle facilities, presence of rail transit, retail and service employment index, and intersection density. All of these models perform similarly (Adj. R2 0.76-0.77) in estimating trip rate adjustments. Data from 34 additional sites were collected to verify the adjustments. For convenience markets and drinking places, the adjustment models were an improvement to the ITE’s handbook method, while adjustments for restaurants tended to perform similarly to those from ITE’s estimation. The approach here is useful in guiding plans and policies for a short-term improvement to the ITE’s Trip Generation Handbook. The measures are useful for communities seeking to develop local adjustments to vehicle trip rate estimates, and all could be calculated from spatial data available in most locations. The paper concludes with a discussion on what long-term improvements to the ITE’s Trip Generation Handbook might entail, with further implications in planning and practice. Title: Adjusting ITE’s Trip Generation Handbook for Urban Context Author: Clifton, Kelly J., Currans, Kristina Marie, Muhs, Christopher D. Year: 2015 This study examines the ways in which urban context affects vehicle trip generation rates across three land uses. An intercept travel survey was administered at 78 establishments (high-turnover restaurants, convenience markets, and drinking places) in the Portland, Oregon, region during 2011. This approach was developed to adjust the Institute of Transportation Engineers (ITE) Trip Generation Handbook vehicle trip rates based on built environment characteristics where the establishments were located. A number of policy-relevant built environment measures were used to estimate a set of nine models predicting an adjustment to ITE trip rates. Each model was estimated as a single measure: activity density, number of transit corridors, number of high-frequency bus lines, employment density, lot coverage, length of bicycle facilities, presence of rail transit, retail and service employment index, and intersection density. All of these models perform similarly (Adj. R2 0.76-0.77) in estimating trip rate adjustments. Data from 34 additional sites were collected to verify the adjustments. For convenience markets and drinking places, the adjustment models were an improvement to the ITE’s handbook method, while adjustments for restaurants tended to perform similarly to those from ITE’s estimation. The approach here is useful in guiding plans and policies for a short-term improvement to the ITE’s Trip Generation Handbook. The measures are useful for communities seeking to develop local adjustments to vehicle trip rate estimates, and all could be calculated from spatial data available in most locations. The paper concludes with a discussion on what long-term improvements to the ITE’s Trip Generation Handbook might entail, with further implications in planning and practice. Close