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• 1. [Article] Assessing the Impact of CMIP5 Climate Multi-Modeling on Estimating the Precipitation Seasonality and Timing

  This paper investigates the effect of a Bayesian Model Averaging (BMA) method on simulated precipitation over the Columbia River Basin using two statistically downscaled climate datasets, i.e., Bias-Correction ...

  Citation × Citation Citation Abstract Copy Title: Assessing the Impact of CMIP5 Climate Multi-Modeling on Estimating the Precipitation Seasonality and Timing Author: Demirel, Mehmet, Moradkhani, Hamid Year: 2015 This paper investigates the effect of a Bayesian Model Averaging (BMA) method on simulated precipitation over the Columbia River Basin using two statistically downscaled climate datasets, i.e., Bias-Correction Spatial Disaggregation (BCSD) and Multivariate Adaptive Constructed Analogs (MACA). To this end daily observed and simulated precipitation are used to calculate different indices focusing solely on seasonality, event-timing, and variability in timing (persistence) of the precipitation. The climate model weights are estimated for each cell (6 × 6 km) of the Columbia River Basin using daily time series for the historical period 1970–1999 from the ten Global Climate Models (GCMs) participating to the Coupled Model Intercomparison Project platform, Phase 5. The results show that BMA results in more than 15 % improvement/reduction in mean absolute error as compared to the individual GCMs. The improvement is, in general, higher for the MACA models than for the BCSD models. The results of variability in precipitation timing show that extreme precipitation events are mostly not persistent (i.e., occurring in different periods throughout the year), i.e., more than 75 % of the grid cells with an elevation above 900 m indicate persistence values less than 0.2 whereas nearly 70 % of the high elevation cells indicate such low persistence. Further we find that the variability in persistence is higher in high elevation cells than those with low elevation. The picture is different for MACA ensembles as the simulated persistence of extreme precipitation events is higher than that for the observed and BCSD datasets. Title: Assessing the Impact of CMIP5 Climate Multi-Modeling on Estimating the Precipitation Seasonality and Timing Author: Demirel, Mehmet, Moradkhani, Hamid Year: 2015 This paper investigates the effect of a Bayesian Model Averaging (BMA) method on simulated precipitation over the Columbia River Basin using two statistically downscaled climate datasets, i.e., Bias-Correction Spatial Disaggregation (BCSD) and Multivariate Adaptive Constructed Analogs (MACA). To this end daily observed and simulated precipitation are used to calculate different indices focusing solely on seasonality, event-timing, and variability in timing (persistence) of the precipitation. The climate model weights are estimated for each cell (6 × 6 km) of the Columbia River Basin using daily time series for the historical period 1970–1999 from the ten Global Climate Models (GCMs) participating to the Coupled Model Intercomparison Project platform, Phase 5. The results show that BMA results in more than 15 % improvement/reduction in mean absolute error as compared to the individual GCMs. The improvement is, in general, higher for the MACA models than for the BCSD models. The results of variability in precipitation timing show that extreme precipitation events are mostly not persistent (i.e., occurring in different periods throughout the year), i.e., more than 75 % of the grid cells with an elevation above 900 m indicate persistence values less than 0.2 whereas nearly 70 % of the high elevation cells indicate such low persistence. Further we find that the variability in persistence is higher in high elevation cells than those with low elevation. The picture is different for MACA ensembles as the simulated persistence of extreme precipitation events is higher than that for the observed and BCSD datasets. Close

• 2. [Article] Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media

  Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations ...

  Citation × Citation Citation Abstract Copy Title: Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media Author: Norwood, Sasha Norien Year: 2013 Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of emerging contaminants (e.g. pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g. chemical composition, shape, aggregation kinetics), solution chemistry (e.g. pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave following several stop flows. While lower aqueous-phase concentrations resulted in significantly longer breakthrough times, the total mass retained in the system was found to be independent of concentration. Additionally, experimental deposition rate coefficients (kd), used to describe deposition kinetics under "clean bed" conditions, were similar across the aqueous-phase concentrations studied. The use of calcium chloride electrolyte solution in transport studies resulted in enhanced mobility relative to potassium chloride suggesting that changes in groundwater solution chemistry could impact mobility of contaminants associated with biosolids. Predicted deposition rate coefficients, using three different models, were found to under- or over-predict values relative to those experimentally determined values depending on the model. This current research has shown that nanocolloids associated with biosolids, specifically Al2O3, are mobile through saturated porous media. Given the ubiquity of nanocolloidal materials, particularly engineered nanomaterials, coupled with the expected increase in land-application of biosolids, a clear understanding of their transport and fate is prudent to understanding the potential impact these emerging pollutants may have on our surface and groundwater bodies. Title: Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media Author: Norwood, Sasha Norien Year: 2013 Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of emerging contaminants (e.g. pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g. chemical composition, shape, aggregation kinetics), solution chemistry (e.g. pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave following several stop flows. While lower aqueous-phase concentrations resulted in significantly longer breakthrough times, the total mass retained in the system was found to be independent of concentration. Additionally, experimental deposition rate coefficients (kd), used to describe deposition kinetics under "clean bed" conditions, were similar across the aqueous-phase concentrations studied. The use of calcium chloride electrolyte solution in transport studies resulted in enhanced mobility relative to potassium chloride suggesting that changes in groundwater solution chemistry could impact mobility of contaminants associated with biosolids. Predicted deposition rate coefficients, using three different models, were found to under- or over-predict values relative to those experimentally determined values depending on the model. This current research has shown that nanocolloids associated with biosolids, specifically Al2O3, are mobile through saturated porous media. Given the ubiquity of nanocolloidal materials, particularly engineered nanomaterials, coupled with the expected increase in land-application of biosolids, a clear understanding of their transport and fate is prudent to understanding the potential impact these emerging pollutants may have on our surface and groundwater bodies. Close

• 3. [Article] Relative Sea-Level Trends in New York City During the Past 1500 Years

  New York City (NYC) is threatened by 21st-century relative sea-level (RSL) rise because it will experience a trend that exceeds the global mean and has high concentrations of low-lying infrastructure and ...

  Citation × Citation Citation Abstract Copy Title: Relative Sea-Level Trends in New York City During the Past 1500 Years Author: Kemp, Andrew C., Hill, Troy D., Vane, Christopher H., Cahill, Niamh, Orton, Philip M., Talke, Stefan A., Parnell, Andrew C., Sanborn, Kelsey, Hartig, Ellen K. Year: 2017 New York City (NYC) is threatened by 21st-century relative sea-level (RSL) rise because it will experience a trend that exceeds the global mean and has high concentrations of low-lying infrastructure and socioeconomic activity. To provide a long-term context for anticipated trends, we reconstructed RSL change during the past ~1500 years using a core of salt-marsh sediment from Pelham Bay in The Bronx. Foraminifera and bulk-sediment δ13C values were used as sea-level indicators. The history of sediment accumulation was established by radiocarbon dating and recognition of pollution and land-use trends of known age in down-core elemental, isotopic, and pollen profiles. The reconstruction was generated within a Bayesian hierarchical model to accommodate multiple proxies and to provide a unified statistical framework for quantifying uncertainty. We show that RSL in NYC rose by ~1.70 m since ~575 CE (including ~0.38 m since 1850 CE). The rate of RSL rise increased markedly at 1812–1913 CE from ~1.0 to ~2.5 mm/yr, which coincides with other reconstructions along the US Atlantic coast. We investigated the possible influence of tidal-range change in Long Island Sound on our reconstruction using a regional tidal model, and we demonstrate that this effect was likely small. However, future tidal-range change could exacerbate the impacts of RSL rise in communities bordering Long Island Sound. The current rate of RSL rise is the fastest that NYC has experienced for >1500 years, and its ongoing acceleration suggests that projections of 21st-century local RSL rise will be realized. Title: Relative Sea-Level Trends in New York City During the Past 1500 Years Author: Kemp, Andrew C., Hill, Troy D., Vane, Christopher H., Cahill, Niamh, Orton, Philip M., Talke, Stefan A., Parnell, Andrew C., Sanborn, Kelsey, Hartig, Ellen K. Year: 2017 New York City (NYC) is threatened by 21st-century relative sea-level (RSL) rise because it will experience a trend that exceeds the global mean and has high concentrations of low-lying infrastructure and socioeconomic activity. To provide a long-term context for anticipated trends, we reconstructed RSL change during the past ~1500 years using a core of salt-marsh sediment from Pelham Bay in The Bronx. Foraminifera and bulk-sediment δ13C values were used as sea-level indicators. The history of sediment accumulation was established by radiocarbon dating and recognition of pollution and land-use trends of known age in down-core elemental, isotopic, and pollen profiles. The reconstruction was generated within a Bayesian hierarchical model to accommodate multiple proxies and to provide a unified statistical framework for quantifying uncertainty. We show that RSL in NYC rose by ~1.70 m since ~575 CE (including ~0.38 m since 1850 CE). The rate of RSL rise increased markedly at 1812–1913 CE from ~1.0 to ~2.5 mm/yr, which coincides with other reconstructions along the US Atlantic coast. We investigated the possible influence of tidal-range change in Long Island Sound on our reconstruction using a regional tidal model, and we demonstrate that this effect was likely small. However, future tidal-range change could exacerbate the impacts of RSL rise in communities bordering Long Island Sound. The current rate of RSL rise is the fastest that NYC has experienced for >1500 years, and its ongoing acceleration suggests that projections of 21st-century local RSL rise will be realized. Close

• 4. [Article] Transient flow inverse study calculation of unsaturated permeability of wood

  One of the major processes in lumber industry is wood drying. This process consumes large amounts of energy and capital, and due to the length of time it takes, it acts as a governing factor in lumber ...

  Citation × Citation Citation Abstract Copy Title: Transient flow inverse study calculation of unsaturated permeability of wood Author: Piroozmandi, Farid Year: 1985 One of the major processes in lumber industry is wood drying. This process consumes large amounts of energy and capital, and due to the length of time it takes, it acts as a governing factor in lumber production levels. Development of improvements in processes and equipment used in wood drying can be expedited through computer simulation of various drying procedures. These numerical simulations depend on the accuracy of numerical models representing wood transport properties, including functional dependency of liquid permeability through wood with respect to local saturation level. Data available in the literature mainly represent wood permeability properties at fully saturated levels. This is an indication of steady state flow methods used in determining these values which are based on wide spread use of similar methods utilized in studies on fluid flow through soil. This research determines unsaturated wood permeability using transient liquid flow methods that are more representative of actual drying process. Initially saturated wood samples are spun in a low speed centrifuge to induce liquid migration through the cell structures. Transient local moisture profiles along the sample are measured using a scanning gamma ray densitometer. Numerical integration and curve fitting procedures are used to process these data. Finally, utilizing liquid continuity equation the functional dependency of permeability with respect to saturation is calculated. Some permeability results appear to be reasonable when compared with actual wood behavior during drying. Measurement procedures prove to yield accurate results for moisture content and saturation levels in wood with less than 5% relative error in average saturation level of .75. However, due to natural inhomogeneities in wood cellular structure, the final calculated results for unsaturated permeability show high levels of uncertainty (up to 112% relative error). Title: Transient flow inverse study calculation of unsaturated permeability of wood Author: Piroozmandi, Farid Year: 1985 One of the major processes in lumber industry is wood drying. This process consumes large amounts of energy and capital, and due to the length of time it takes, it acts as a governing factor in lumber production levels. Development of improvements in processes and equipment used in wood drying can be expedited through computer simulation of various drying procedures. These numerical simulations depend on the accuracy of numerical models representing wood transport properties, including functional dependency of liquid permeability through wood with respect to local saturation level. Data available in the literature mainly represent wood permeability properties at fully saturated levels. This is an indication of steady state flow methods used in determining these values which are based on wide spread use of similar methods utilized in studies on fluid flow through soil. This research determines unsaturated wood permeability using transient liquid flow methods that are more representative of actual drying process. Initially saturated wood samples are spun in a low speed centrifuge to induce liquid migration through the cell structures. Transient local moisture profiles along the sample are measured using a scanning gamma ray densitometer. Numerical integration and curve fitting procedures are used to process these data. Finally, utilizing liquid continuity equation the functional dependency of permeability with respect to saturation is calculated. Some permeability results appear to be reasonable when compared with actual wood behavior during drying. Measurement procedures prove to yield accurate results for moisture content and saturation levels in wood with less than 5% relative error in average saturation level of .75. However, due to natural inhomogeneities in wood cellular structure, the final calculated results for unsaturated permeability show high levels of uncertainty (up to 112% relative error). Close

• 5. [Article] The Influence of Oceanic Swell on Flows Over an Estuarine Intertidal Mudflat in San Francisco Bay

  this study, we examine the role that remotely forced ocean waves play in the hydrodynamics of an intertidal, estuarine mudflat. The observations indicate that long-period (10–20 s) ocean waves are a potentially ...

  Citation × Citation Citation Abstract Copy Title: The Influence of Oceanic Swell on Flows Over an Estuarine Intertidal Mudflat in San Francisco Bay Author: Talke, Stefan, Stacey, M. Year: 2003 this study, we examine the role that remotely forced ocean waves play in the hydrodynamics of an intertidal, estuarine mudflat. The observations indicate that long-period (10–20 s) ocean waves are a potentially important source of near-bed energy and shear stress in this environment. Over a two-week period in February 2001, we deployed an autonomous SonTek Hydra system on a mudflat in Central San Francisco Bay, and measured velocity and sediment concentration approximately 10 cm from the bed using an acoustic Doppler velocimeter (ADV) and an optical backscatter sensor (OBS). The experiment continued through wet (high tide) and dry (low tide) periods over an entire spring–neap cycle, and thus included the variation of near-bed velocity over a range of timescales. Results show that during large ebb tides, tidally forced flows dominate the near-bed dynamics during calm conditions. Wind waves dominate whenever the wind direction exposes the mudflat to wind coming off the bay (from the south and southwest), as occurs during winter storms. During periods when tidal forcing is limited and wind waves are small, remotely forced ocean swells become an important energy source. These motions appear in the burst samples at frequencies between 0.1 and 0.04 Hz and their energy correlates well (ρ>0.8) with ocean swell measured from a buoy offshore of San Francisco. Spectral analysis of data shows that the average energy of ocean waves per tide varied between 2 and 15% of total energy load. Moreover, extreme values in the distribution of ocean waves bring episodic bursts of greater energy onto the estuarine mudflat, which may influence local suspension of sediments. Title: The Influence of Oceanic Swell on Flows Over an Estuarine Intertidal Mudflat in San Francisco Bay Author: Talke, Stefan, Stacey, M. Year: 2003 this study, we examine the role that remotely forced ocean waves play in the hydrodynamics of an intertidal, estuarine mudflat. The observations indicate that long-period (10–20 s) ocean waves are a potentially important source of near-bed energy and shear stress in this environment. Over a two-week period in February 2001, we deployed an autonomous SonTek Hydra system on a mudflat in Central San Francisco Bay, and measured velocity and sediment concentration approximately 10 cm from the bed using an acoustic Doppler velocimeter (ADV) and an optical backscatter sensor (OBS). The experiment continued through wet (high tide) and dry (low tide) periods over an entire spring–neap cycle, and thus included the variation of near-bed velocity over a range of timescales. Results show that during large ebb tides, tidally forced flows dominate the near-bed dynamics during calm conditions. Wind waves dominate whenever the wind direction exposes the mudflat to wind coming off the bay (from the south and southwest), as occurs during winter storms. During periods when tidal forcing is limited and wind waves are small, remotely forced ocean swells become an important energy source. These motions appear in the burst samples at frequencies between 0.1 and 0.04 Hz and their energy correlates well (ρ>0.8) with ocean swell measured from a buoy offshore of San Francisco. Spectral analysis of data shows that the average energy of ocean waves per tide varied between 2 and 15% of total energy load. Moreover, extreme values in the distribution of ocean waves bring episodic bursts of greater energy onto the estuarine mudflat, which may influence local suspension of sediments. Close

• 6. [Article] Strength And Fatigue Of Three Glass Fiber Reinforced Composite Bridge Decks With Mechanical Deck To Stringer Connections

  Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated ...

  Citation × Citation Citation Abstract Copy Title: Strength And Fatigue Of Three Glass Fiber Reinforced Composite Bridge Decks With Mechanical Deck To Stringer Connections Author: Gleason, Andrew, Dusicka, Peter Year: 2012 Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated existing deck, improve driver safety and introduce bridge water runoff treatment. This report outlines the testing methods and results of an experimental program aimed primarily at evaluating a new open cell deck. While most FRP panels are connected via shear studs that are grouted within isolated pockets, the panels in this case were bolted directly to the steel stringers. Two different FRP deck options were evaluated for comparison: one with open cells and the other with more conventional closed box extrusions. The objective was to evaluate the strength of the FRP to steel stringer connection with individual bolt connection tests, the strength and fatigue resistance of the FRP decks themselves, and the relative lateral stiffness contribution of the panels. Additional related tests were also included to complement the research effort such as the inclusion of tests on a closed box deck removed from the Broadway Bridge in Portland, OR, and strength tests of a retrofit attachment option of FRP deck to stringer using bolted clamps. While the monotonic, flexural, and shear strength of the deck exceeded the design values, the associated failure mode of the open cell panels was consistently via shear flow through the stem near the top flange. The residual displacement of failed FRP decks was found to be minimal, which would make visual identification of failed panels without applied load difficult in the field. Fatigue strength evaluation was conducted with two different protocols, where one was run to over 6 million cycles based on AASHTO defined loading and the other to 2 million cycles with higher than AASHTO defined loading. Fatigue failure was observed in only one specimen that was subjected to the higher loading condition, providing a sense of fatigue life of this material. Fatigue failure mode initiated in flexural fiber rupture, which was different to monotonic tests under the same loading configurations. Bolted deck to steel stringer connection tests indicated failure modes in the FRP with strength values that were in certain configurations well below the strength of the bolts. For cases where the bolted FRP deck was counted on to provide lateral stiffness, such as the case in the raised configuration of the bascule span, the closed cell was found to have approximately twice the stiffness. The results of these tests provide valuable data that can be applied to FRP bridge deck designs that utilize bolted connections and open and closed cell deck configurations under high traffic volumes. Title: Strength And Fatigue Of Three Glass Fiber Reinforced Composite Bridge Decks With Mechanical Deck To Stringer Connections Author: Gleason, Andrew, Dusicka, Peter Year: 2012 Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated existing deck, improve driver safety and introduce bridge water runoff treatment. This report outlines the testing methods and results of an experimental program aimed primarily at evaluating a new open cell deck. While most FRP panels are connected via shear studs that are grouted within isolated pockets, the panels in this case were bolted directly to the steel stringers. Two different FRP deck options were evaluated for comparison: one with open cells and the other with more conventional closed box extrusions. The objective was to evaluate the strength of the FRP to steel stringer connection with individual bolt connection tests, the strength and fatigue resistance of the FRP decks themselves, and the relative lateral stiffness contribution of the panels. Additional related tests were also included to complement the research effort such as the inclusion of tests on a closed box deck removed from the Broadway Bridge in Portland, OR, and strength tests of a retrofit attachment option of FRP deck to stringer using bolted clamps. While the monotonic, flexural, and shear strength of the deck exceeded the design values, the associated failure mode of the open cell panels was consistently via shear flow through the stem near the top flange. The residual displacement of failed FRP decks was found to be minimal, which would make visual identification of failed panels without applied load difficult in the field. Fatigue strength evaluation was conducted with two different protocols, where one was run to over 6 million cycles based on AASHTO defined loading and the other to 2 million cycles with higher than AASHTO defined loading. Fatigue failure was observed in only one specimen that was subjected to the higher loading condition, providing a sense of fatigue life of this material. Fatigue failure mode initiated in flexural fiber rupture, which was different to monotonic tests under the same loading configurations. Bolted deck to steel stringer connection tests indicated failure modes in the FRP with strength values that were in certain configurations well below the strength of the bolts. For cases where the bolted FRP deck was counted on to provide lateral stiffness, such as the case in the raised configuration of the bascule span, the closed cell was found to have approximately twice the stiffness. The results of these tests provide valuable data that can be applied to FRP bridge deck designs that utilize bolted connections and open and closed cell deck configurations under high traffic volumes. Close

• 7. [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