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• 1. [Article] Toward a Spatial-Temporal Measure of Land-Use Mix

  Urban planning and public-health research has long been interested in the connection between land-use mix and travel. Interest from urban planners stems from the potential of transportation efficiency ...

  Citation × Citation Citation Abstract Copy Title: Toward a Spatial-Temporal Measure of Land-Use Mix Author: Gehrke, Steven R., Clifton, Kelly Year: 2015 Urban planning and public-health research has long been interested in the connection between land-use mix and travel. Interest from urban planners stems from the potential of transportation efficiency gains achieved by an increased land-use mix and subsequent shortening of trip lengths; whereas, public-health research advocates an increased land-use mix as an effective policy for facilitating greater physical activity. Yet, despite the transportation, land-use, and health benefits related to improving land-use mix and the extent of topical attention given by researchers, no consensus has been reached regarding the magnitude of its effect on travel. This absence of agreement may largely be attributed to the theoretical and methodological failings persistent in present attempts to accurately reflect land-use interaction and operationalize its quantification within a defined spatial extent. To better evaluate the impact of land-use mix on travel behavior and assess more temporal policies, a robust mix measure accounting for these two elements of land-use interaction and geographic scale as well as a temporal element of land-use mixing—missing from present specifications—must be introduced. This paper establishes the research agenda for a spatial-temporal land-use mix measure by (1) identifying the conceptual and methodological faults inherent to current land-use interaction and geographic-scale representations and (2) describing strategies and practical benefits of representing the temporal availability of land-use mixing in guiding innovative transportation/land-use policies. Title: Toward a Spatial-Temporal Measure of Land-Use Mix Author: Gehrke, Steven R., Clifton, Kelly Year: 2015 Urban planning and public-health research has long been interested in the connection between land-use mix and travel. Interest from urban planners stems from the potential of transportation efficiency gains achieved by an increased land-use mix and subsequent shortening of trip lengths; whereas, public-health research advocates an increased land-use mix as an effective policy for facilitating greater physical activity. Yet, despite the transportation, land-use, and health benefits related to improving land-use mix and the extent of topical attention given by researchers, no consensus has been reached regarding the magnitude of its effect on travel. This absence of agreement may largely be attributed to the theoretical and methodological failings persistent in present attempts to accurately reflect land-use interaction and operationalize its quantification within a defined spatial extent. To better evaluate the impact of land-use mix on travel behavior and assess more temporal policies, a robust mix measure accounting for these two elements of land-use interaction and geographic scale as well as a temporal element of land-use mixing—missing from present specifications—must be introduced. This paper establishes the research agenda for a spatial-temporal land-use mix measure by (1) identifying the conceptual and methodological faults inherent to current land-use interaction and geographic-scale representations and (2) describing strategies and practical benefits of representing the temporal availability of land-use mixing in guiding innovative transportation/land-use policies. Close

• 2. [Article] Do Characteristics of Walkable Environments Support Bicycling? Toward a Definition of Bicycle-Supported Development

  Does walkability equate with bikeability? Through a comprehensive review of studies of the built environment and bicycling, including mode choice, route choice, safety, and urban design literature, this ...

  Citation × Citation Citation Abstract Copy Title: Do Characteristics of Walkable Environments Support Bicycling? Toward a Definition of Bicycle-Supported Development Author: Muhs, Christopher D., Clifton, Kelly Year: 2016 Does walkability equate with bikeability? Through a comprehensive review of studies of the built environment and bicycling, including mode choice, route choice, safety, and urban design literature, this paper addresses this question. Previous work has raised the issue that the two modes are functionally different, despite them often being combined into a nonmotorized category, and has highlighted research challenges. Existing studies of bikeability have largely focused on infrastructure. This paper contributes to the literature on bicycling and the built environment by providing a thorough review of past research with a focus on the relationships between land use, urban form, and bicycling. Highly walkable and highly bikeable environments are quite different, and there is little consistency in the built-environment attributes associated with cycling across studies. We postulate that this inconsistency is due in part to a disconnect between theory and methods of measuring the environment for cycling along with data limitations, including sample sizes and our understanding being based mainly on cross-sectional data. Many research opportunities are present for land-use planning policies now that planning for cycling is a top priority for cities and regions across the world. Title: Do Characteristics of Walkable Environments Support Bicycling? Toward a Definition of Bicycle-Supported Development Author: Muhs, Christopher D., Clifton, Kelly Year: 2016 Does walkability equate with bikeability? Through a comprehensive review of studies of the built environment and bicycling, including mode choice, route choice, safety, and urban design literature, this paper addresses this question. Previous work has raised the issue that the two modes are functionally different, despite them often being combined into a nonmotorized category, and has highlighted research challenges. Existing studies of bikeability have largely focused on infrastructure. This paper contributes to the literature on bicycling and the built environment by providing a thorough review of past research with a focus on the relationships between land use, urban form, and bicycling. Highly walkable and highly bikeable environments are quite different, and there is little consistency in the built-environment attributes associated with cycling across studies. We postulate that this inconsistency is due in part to a disconnect between theory and methods of measuring the environment for cycling along with data limitations, including sample sizes and our understanding being based mainly on cross-sectional data. Many research opportunities are present for land-use planning policies now that planning for cycling is a top priority for cities and regions across the world. Close

• 3. [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

• 4. [Article] Wider Dissemination of Household Travel Survey Data Using Geographical Perturbation Methods

  Public agencies spend vast amounts of money collecting information about passenger travel in household travel surveys. These data are valuable for the rich and detailed information they provide, which ...

  Citation × Citation Citation Abstract Copy Title: Wider Dissemination of Household Travel Survey Data Using Geographical Perturbation Methods Author: Clifton, Kelly J., Gehrke, Steven R. Year: 2014 Public agencies spend vast amounts of money collecting information about passenger travel in household travel surveys. These data are valuable for the rich and detailed information they provide, which contribute to regional and statewide travel demand models. These data have utility beyond travel demand modeling in their application to transportation policy and travel behavior research. As the demand on these data increase, so have the quantity of information collected. Detailed geospatial referencing of the home, work and other travel destinations are common practice and permit the integration with other spatially archived data sources, such as land use characteristics, transportation system information, and other built environment, social and economic data. Other public agencies, private consultancies, non-profits and educational institutions may benefit from access to the original data with applications to areas such public health, equity, transportation safety and urban planning. Oregon Modeling Collaborative (OMC) has entered into an agreement with Oregon Modeling Steering Committee (OMSC) to host and make available Oregon Household Activity Survey (OHAS) datasets. But wide distribution of these important and expensive data is limited by the requirement to protect the confidentiality of survey participants, who are guaranteed anonymity in exchange for participation. Data are often aggregated to a geographic level such as Census tracts or transportation analysis zones (TAZs) before disseminating to the public, which limits the utility of this information. This project aims to develop a methodology to permit dissemination of these spatially-explicit data to a wider range of public constituents while at the same time, protecting the identities of study participants. Making use of these data, this project will use geographical perturbation methods to add noise to the original data to protect confidentiality while at the same time allowing the detailed geo-spatial referencing to be included in the disseminated data. The process includes: The coordinates (locations) will be geographically perturbed (masked) so that they do not reveal the identity of the traveler while at the same time retaining spatial relevance and resolution. Here the limits of the perturbation (minimum and maximum displacement) need to be determined that a) ensure confidentiality and b) minimize the errors introduced to the data. The original and perturbed (masked) data will be compared using various statistical approaches to develop a set of confidence measures for different types of transportation applications. For example, geographically perturbed (masked) may be more robust for automobile travel measures, such as vehicle miles traveled (VMT) or transit accessibility than for detailed pedestrian or bicycle trip attributes. This exercise will allow spatially-explicit OHAS data to be released to the public with some information about the confidence to which it can be applied. These data will be archived at Portland State University and made available to the public. The information and algorithms can be shared with other agencies collecting and archiving travel data, such as the National Household Travel Survey, metropolitan planning organizations and state departments of transportation, to permit wider dissemination of their data. Title: Wider Dissemination of Household Travel Survey Data Using Geographical Perturbation Methods Author: Clifton, Kelly J., Gehrke, Steven R. Year: 2014 Public agencies spend vast amounts of money collecting information about passenger travel in household travel surveys. These data are valuable for the rich and detailed information they provide, which contribute to regional and statewide travel demand models. These data have utility beyond travel demand modeling in their application to transportation policy and travel behavior research. As the demand on these data increase, so have the quantity of information collected. Detailed geospatial referencing of the home, work and other travel destinations are common practice and permit the integration with other spatially archived data sources, such as land use characteristics, transportation system information, and other built environment, social and economic data. Other public agencies, private consultancies, non-profits and educational institutions may benefit from access to the original data with applications to areas such public health, equity, transportation safety and urban planning. Oregon Modeling Collaborative (OMC) has entered into an agreement with Oregon Modeling Steering Committee (OMSC) to host and make available Oregon Household Activity Survey (OHAS) datasets. But wide distribution of these important and expensive data is limited by the requirement to protect the confidentiality of survey participants, who are guaranteed anonymity in exchange for participation. Data are often aggregated to a geographic level such as Census tracts or transportation analysis zones (TAZs) before disseminating to the public, which limits the utility of this information. This project aims to develop a methodology to permit dissemination of these spatially-explicit data to a wider range of public constituents while at the same time, protecting the identities of study participants. Making use of these data, this project will use geographical perturbation methods to add noise to the original data to protect confidentiality while at the same time allowing the detailed geo-spatial referencing to be included in the disseminated data. The process includes: The coordinates (locations) will be geographically perturbed (masked) so that they do not reveal the identity of the traveler while at the same time retaining spatial relevance and resolution. Here the limits of the perturbation (minimum and maximum displacement) need to be determined that a) ensure confidentiality and b) minimize the errors introduced to the data. The original and perturbed (masked) data will be compared using various statistical approaches to develop a set of confidence measures for different types of transportation applications. For example, geographically perturbed (masked) may be more robust for automobile travel measures, such as vehicle miles traveled (VMT) or transit accessibility than for detailed pedestrian or bicycle trip attributes. This exercise will allow spatially-explicit OHAS data to be released to the public with some information about the confidence to which it can be applied. These data will be archived at Portland State University and made available to the public. The information and algorithms can be shared with other agencies collecting and archiving travel data, such as the National Household Travel Survey, metropolitan planning organizations and state departments of transportation, to permit wider dissemination of their data. Close

• 5. [Article] Examining Consumer Behavior and Travel Choices

  This study represents a first attempt to answer a few of the questions that have arisen concerning multimodal transportation investments and the impacts of mode shifts on the business community. This research ...

  Citation × Citation Citation Abstract Copy Title: Examining Consumer Behavior and Travel Choices Author: Clifton, Kelly J., Muhs, Christopher Devlin, Morrissey, Sara, Morrissey, Tomás, Currans, Kristina Marie, Ritter, Chloe Year: 2013 This study represents a first attempt to answer a few of the questions that have arisen concerning multimodal transportation investments and the impacts of mode shifts on the business community. This research aims to merge the long history of scholarly work that examines the impacts of the built environment on non-work travel with the relatively new interest in consumer spending by mode of travel. This empirical study of travel choices and consumer spending across 89 businesses in the Portland metropolitan area shows there are important differences between the amounts customers spend on average at various businesses by their mode of travel. However, these differences become less pronounced when we control for demographics of the customer and other attributes of the trip. This study of consumer spending and travel choices has some compelling findings that suggest some key spending and frequency differences by mode of travel that will likely invigorate the discussion of the economic impacts of these modes. Key findings are: 1) Bicyclists, pedestrians and transit riders are competitive consumers: When demographics and socioeconomics are controlled for, mode choice does not have a statistically significant impact on consumer spending at convenience stores, drinking establishments and restaurants. When trip frequency is accounted for, the average monthly expenditures by customer modes of travel reveal that bicyclists, transit users and pedestrians are competitive consumers and, for all businesses except supermarkets, spend more on average than those who drive and 2) The built environment matters: We support previous literature and find that residential and employment density, the proximity to rail transit, and the amount of automobile and bicycle parking are all important in explaining the use of non-automobile modes. In particular, provision of bike parking and bike corrals are significant predictors of bike mode share at the establishment level. Other findings lend more insight into the relationship between consumer behavior and travel choices. For the non-work destinations studied, the automobile remains the dominant mode of travel. Patrons are largely arriving by private vehicle to most of the destinations in this study, particularly to grocery stores where larger quantities of goods tend to be purchased. But, high non-automobile mode shares and short travel distances exist in areas of concentrated urban activity. In sum, this study provides some empirical evidence to answer the questions of business owners about how mode shifts might impact their market shares and revenues. More work is needed to better understand the implications of future changes and to provide a robust assessment of the returns on these investments and their economic impacts. Title: Examining Consumer Behavior and Travel Choices Author: Clifton, Kelly J., Muhs, Christopher Devlin, Morrissey, Sara, Morrissey, Tomás, Currans, Kristina Marie, Ritter, Chloe Year: 2013 This study represents a first attempt to answer a few of the questions that have arisen concerning multimodal transportation investments and the impacts of mode shifts on the business community. This research aims to merge the long history of scholarly work that examines the impacts of the built environment on non-work travel with the relatively new interest in consumer spending by mode of travel. This empirical study of travel choices and consumer spending across 89 businesses in the Portland metropolitan area shows there are important differences between the amounts customers spend on average at various businesses by their mode of travel. However, these differences become less pronounced when we control for demographics of the customer and other attributes of the trip. This study of consumer spending and travel choices has some compelling findings that suggest some key spending and frequency differences by mode of travel that will likely invigorate the discussion of the economic impacts of these modes. Key findings are: 1) Bicyclists, pedestrians and transit riders are competitive consumers: When demographics and socioeconomics are controlled for, mode choice does not have a statistically significant impact on consumer spending at convenience stores, drinking establishments and restaurants. When trip frequency is accounted for, the average monthly expenditures by customer modes of travel reveal that bicyclists, transit users and pedestrians are competitive consumers and, for all businesses except supermarkets, spend more on average than those who drive and 2) The built environment matters: We support previous literature and find that residential and employment density, the proximity to rail transit, and the amount of automobile and bicycle parking are all important in explaining the use of non-automobile modes. In particular, provision of bike parking and bike corrals are significant predictors of bike mode share at the establishment level. Other findings lend more insight into the relationship between consumer behavior and travel choices. For the non-work destinations studied, the automobile remains the dominant mode of travel. Patrons are largely arriving by private vehicle to most of the destinations in this study, particularly to grocery stores where larger quantities of goods tend to be purchased. But, high non-automobile mode shares and short travel distances exist in areas of concentrated urban activity. In sum, this study provides some empirical evidence to answer the questions of business owners about how mode shifts might impact their market shares and revenues. More work is needed to better understand the implications of future changes and to provide a robust assessment of the returns on these investments and their economic impacts. Close