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• 1. [Article] A Level-of-Service Model for Protected Bike Lanes

  Several methods exist for quantifying the quality of service provided by a roadway from a bicyclist’s perspective; however, many of these models do not consider physically protected bike lanes and, of ...

  Citation × Citation Citation Abstract Copy Title: A Level-of-Service Model for Protected Bike Lanes Author: Foster, Nick, Monsere, Christopher, Dill, Jennifer, Clifton, Kelly Year: 2015 Several methods exist for quantifying the quality of service provided by a roadway from a bicyclist’s perspective; however, many of these models do not consider physically protected bike lanes and, of those that do, none is based on empirical data from the US. This is problematic as engineers, planners, and elected officials are increasingly looking to objective performance measures to help guide transportation project design and funding prioritization decisions. This paper addresses this gap by presenting a cumulative logistic model to predict user comfort on protected bike lanes developed from data collected during in-person video surveys. The surveys were conducted in Portland, OR with video footage gathered in Chicago, IL, Portland, OR and San Francisco, CA. The model is for road segments only and not signalized intersections. It complements the Highway Capacity Manual 2010 level-of- service methods by providing an analysis procedure for a facility type that is not currently included in the manual. The model indicates that the type of buffer, direction of travel (one-way vs. two-way), adjacent motor vehicle speed limit, and average daily motor vehicle volumes are all significant predictors of bicyclist comfort in protected bike lanes. The model predicts a mean value of ‘A’ or ‘B’ on an A (most comfortable) – F (least comfortable) scale for all protected bike lane clips used in the survey. Consistent with previous research findings, survey respondents report that protected bike lanes are generally more comfortable than other types of on-street infrastructure. Title: A Level-of-Service Model for Protected Bike Lanes Author: Foster, Nick, Monsere, Christopher, Dill, Jennifer, Clifton, Kelly Year: 2015 Several methods exist for quantifying the quality of service provided by a roadway from a bicyclist’s perspective; however, many of these models do not consider physically protected bike lanes and, of those that do, none is based on empirical data from the US. This is problematic as engineers, planners, and elected officials are increasingly looking to objective performance measures to help guide transportation project design and funding prioritization decisions. This paper addresses this gap by presenting a cumulative logistic model to predict user comfort on protected bike lanes developed from data collected during in-person video surveys. The surveys were conducted in Portland, OR with video footage gathered in Chicago, IL, Portland, OR and San Francisco, CA. The model is for road segments only and not signalized intersections. It complements the Highway Capacity Manual 2010 level-of- service methods by providing an analysis procedure for a facility type that is not currently included in the manual. The model indicates that the type of buffer, direction of travel (one-way vs. two-way), adjacent motor vehicle speed limit, and average daily motor vehicle volumes are all significant predictors of bicyclist comfort in protected bike lanes. The model predicts a mean value of ‘A’ or ‘B’ on an A (most comfortable) – F (least comfortable) scale for all protected bike lane clips used in the survey. Consistent with previous research findings, survey respondents report that protected bike lanes are generally more comfortable than other types of on-street infrastructure. Close

• 2. [Article] Towards Effective Design Treatment for Right Turns at Intersections with Bicycle Traffic

  The overall goal of this research was to quantify the safety performance of alternative traffic control strategies to mitigate right-turning vehicle-bicycle crashes at signalized intersections in Oregon. ...

  Citation × Citation Citation Abstract Copy Title: Towards Effective Design Treatment for Right Turns at Intersections with Bicycle Traffic Author: Hurwitz, David, Jannat, Mafruhatul, Warner, Jennifer, Monsere, Christopher M., Razmpa, Ali Year: 2015 The overall goal of this research was to quantify the safety performance of alternative traffic control strategies to mitigate right-turning vehicle-bicycle crashes at signalized intersections in Oregon. The ultimate aim was to provide useful design guidance to potentially mitigate these collision types at the critical intersection configurations. This report includes a comprehensive review of more than 150 scientific and technical articles that relate to bicycle-motor vehicle crashes. A total of 504 right-hook crashes were identified from vehicle path information in the Oregon crash data from 2007-2011, mapped and reviewed in detail to identify the frequency and severity of crashes by intersection lane configuration and traffic control. Based on these efforts, a two stage experiment was developed in the Oregon State University (OSU) high-fidelity driving simulator to investigate the causal factors of right-hook crashes at signalized intersections with a striped bike lane and no right-turn lane, and to then identify and evaluate alternative design treatments that could mitigate the occurrence of right-hook crashes. Experiment 1 investigated motorist and environmental related causal factors of right-hook crashes, using three different motorist performance measures: (1) visual attention, (2) situational awareness (SA) and (3) crash avoidance behavior. Data was collected from 51 participants (30 male and 21 female) turning right 820 times in 21 different experimental scenarios. It was determined that the worst case right-hook scenario occurred when a bicycle was approaching the intersection at a higher speed (16 mph) and positioned in the blind zone of the motorist. In crash and near crash situations (measured by time-to-collision) the most common cause was a failure of the driver to actively search for the adjacent bicyclist (situational awareness level 1), although failures were also determined to occur due to failures of projection (i.e. incorrectly assuming that the bicycle would yield or that there was enough time to turn in front of the bicycle). Elements of driver performance and gap acceptance collected in the first stage simulator experiment were field validated to provide additional confidence in the findings. The research reviewed 144 hours of video and identified 43 conflicts where the time-to-collision (TTC) measured less than 5 seconds. When field observations of scenarios most similar to those in the simulator were isolated, the analysis indicated that the distribution of the TTCs values observed in the simulator were consistent with those observed in the field. Experiment 2 evaluated several possible design treatments, (specifically: signage, pavement markings, curb radii, and protected intersection designs), based on the visual attention of motorist, their crash avoidance behavior, and the severity of the observed crashes. Data was collected from 28 participants (18 male and 10 female) turning right 596 times in 22 scenarios that were used. The resulting analysis of the driver performance indicators suggest that while various driver performance metrics can be measured robustly, and all of the treatments had some positive effect on measured driver performance, it is not yet clear how to map the magnitudes of the differences to expected crash outcomes. Additional work is recommended to address the limitations of this study and to further consider the potential effects of the right-hook crash mitigation strategies from this research. Title: Towards Effective Design Treatment for Right Turns at Intersections with Bicycle Traffic Author: Hurwitz, David, Jannat, Mafruhatul, Warner, Jennifer, Monsere, Christopher M., Razmpa, Ali Year: 2015 The overall goal of this research was to quantify the safety performance of alternative traffic control strategies to mitigate right-turning vehicle-bicycle crashes at signalized intersections in Oregon. The ultimate aim was to provide useful design guidance to potentially mitigate these collision types at the critical intersection configurations. This report includes a comprehensive review of more than 150 scientific and technical articles that relate to bicycle-motor vehicle crashes. A total of 504 right-hook crashes were identified from vehicle path information in the Oregon crash data from 2007-2011, mapped and reviewed in detail to identify the frequency and severity of crashes by intersection lane configuration and traffic control. Based on these efforts, a two stage experiment was developed in the Oregon State University (OSU) high-fidelity driving simulator to investigate the causal factors of right-hook crashes at signalized intersections with a striped bike lane and no right-turn lane, and to then identify and evaluate alternative design treatments that could mitigate the occurrence of right-hook crashes. Experiment 1 investigated motorist and environmental related causal factors of right-hook crashes, using three different motorist performance measures: (1) visual attention, (2) situational awareness (SA) and (3) crash avoidance behavior. Data was collected from 51 participants (30 male and 21 female) turning right 820 times in 21 different experimental scenarios. It was determined that the worst case right-hook scenario occurred when a bicycle was approaching the intersection at a higher speed (16 mph) and positioned in the blind zone of the motorist. In crash and near crash situations (measured by time-to-collision) the most common cause was a failure of the driver to actively search for the adjacent bicyclist (situational awareness level 1), although failures were also determined to occur due to failures of projection (i.e. incorrectly assuming that the bicycle would yield or that there was enough time to turn in front of the bicycle). Elements of driver performance and gap acceptance collected in the first stage simulator experiment were field validated to provide additional confidence in the findings. The research reviewed 144 hours of video and identified 43 conflicts where the time-to-collision (TTC) measured less than 5 seconds. When field observations of scenarios most similar to those in the simulator were isolated, the analysis indicated that the distribution of the TTCs values observed in the simulator were consistent with those observed in the field. Experiment 2 evaluated several possible design treatments, (specifically: signage, pavement markings, curb radii, and protected intersection designs), based on the visual attention of motorist, their crash avoidance behavior, and the severity of the observed crashes. Data was collected from 28 participants (18 male and 10 female) turning right 596 times in 22 scenarios that were used. The resulting analysis of the driver performance indicators suggest that while various driver performance metrics can be measured robustly, and all of the treatments had some positive effect on measured driver performance, it is not yet clear how to map the magnitudes of the differences to expected crash outcomes. Additional work is recommended to address the limitations of this study and to further consider the potential effects of the right-hook crash mitigation strategies from this research. Close