Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of poli...Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of policy and planning decisions. In this paper we quantify the expected air quality impacts of increased traffic due to a proposed new university campus extension in Chapel Hill, North Carolina. In so doing, we build the evidence base for quantitative HIA in the United States and develop an improved approach for forecasting traffic effects on exposure to ambient fine particulate matter (PM2.5) in air. Very few previous US HIAs have quantified health impacts and instead have relied on stakeholder intuition to decide whether effects will be positive, negative, or neutral. Our method uses an air dispersion model known as CAL3QHCR to predict changes in exposure to airborne, traffic-related PM2.5 that could occur due to the proposed new campus development. We employ CAL3QHCR in a new way to better represent variability in road grade, vehicle driving patterns (speed, acceleration, deceleration, and idling), and meteorology. In a comparison of model predictions to measured PM2.5 concentrations, we found that the model estimated PM2.5 dispersion to within a factor of two for 75% of data points, which is within the typical benchmark used for model performance evaluation. Applying the model to present-day conditions in the study area, we found that current traffic contributes a relatively small amount to ambient PM2.5 concentrations: about 0.14 μg/m3 in the most exposed neighborhood—relatively low in comparison to the current US National Ambient Air Quality Standard of 12 μg/m3. Notably, even though the new campus is expected to bring an additional 40,000 daily trips to the study community by the year 2025, vehicle-related PM2.5 emissions are expected to decrease compared to current conditions due to anticipated improvements in vehicle technologies and cleaner fuels.展开更多
The reduction of speed limits in urban roads through traffic calming schemes intends to ensure safer traffic conditions among road users by reducing the probability related to the occurrence of severe accident.Looking...The reduction of speed limits in urban roads through traffic calming schemes intends to ensure safer traffic conditions among road users by reducing the probability related to the occurrence of severe accident.Looking it from a different perspective,traffic calming measures can potentially resolve congestion problems at the same time by lowering the overall accessibility and attractiveness of private cars in urban areas.This study proposes a new methodological approach to explore and assess the direct impacts of traffic calming in the transport system efficiency of a metropolitan area.The multi-agent transport simulation(MATSim)and Open-Berlin scenario are utilized to perform this simulation experiment.By developing a new external tool,the free flow speed and road capacity of each network link is updated based on new speed limits and different compliance rates,which are defined per road hierarchy level.The test scenarios that are formulated present radical conditions,where the speed limit in most urban roads of Berlin drops to 30 km/h or even 15 km/h.The findings of this study show a considerably high increase in trips,passenger hours,and passenger kilometers using public transport modes,when traffic calming links are introduced,the reserve change is observed in private cars trips.Although the speed limits are decreased in inner urban roads in most of the scenarios,the decrease of average travel speed of private cars is not so high as it was expected.Surprisingly,private cars are used for longer distances in all test scenarios.Car drivers seem to use already existed motorways and private road to commute.In simulations,driver compliance to the new speed limits seems to be a determinant factor that is strongly influenced by the design interventions applied in a traffic calming area.展开更多
文摘Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of policy and planning decisions. In this paper we quantify the expected air quality impacts of increased traffic due to a proposed new university campus extension in Chapel Hill, North Carolina. In so doing, we build the evidence base for quantitative HIA in the United States and develop an improved approach for forecasting traffic effects on exposure to ambient fine particulate matter (PM2.5) in air. Very few previous US HIAs have quantified health impacts and instead have relied on stakeholder intuition to decide whether effects will be positive, negative, or neutral. Our method uses an air dispersion model known as CAL3QHCR to predict changes in exposure to airborne, traffic-related PM2.5 that could occur due to the proposed new campus development. We employ CAL3QHCR in a new way to better represent variability in road grade, vehicle driving patterns (speed, acceleration, deceleration, and idling), and meteorology. In a comparison of model predictions to measured PM2.5 concentrations, we found that the model estimated PM2.5 dispersion to within a factor of two for 75% of data points, which is within the typical benchmark used for model performance evaluation. Applying the model to present-day conditions in the study area, we found that current traffic contributes a relatively small amount to ambient PM2.5 concentrations: about 0.14 μg/m3 in the most exposed neighborhood—relatively low in comparison to the current US National Ambient Air Quality Standard of 12 μg/m3. Notably, even though the new campus is expected to bring an additional 40,000 daily trips to the study community by the year 2025, vehicle-related PM2.5 emissions are expected to decrease compared to current conditions due to anticipated improvements in vehicle technologies and cleaner fuels.
文摘The reduction of speed limits in urban roads through traffic calming schemes intends to ensure safer traffic conditions among road users by reducing the probability related to the occurrence of severe accident.Looking it from a different perspective,traffic calming measures can potentially resolve congestion problems at the same time by lowering the overall accessibility and attractiveness of private cars in urban areas.This study proposes a new methodological approach to explore and assess the direct impacts of traffic calming in the transport system efficiency of a metropolitan area.The multi-agent transport simulation(MATSim)and Open-Berlin scenario are utilized to perform this simulation experiment.By developing a new external tool,the free flow speed and road capacity of each network link is updated based on new speed limits and different compliance rates,which are defined per road hierarchy level.The test scenarios that are formulated present radical conditions,where the speed limit in most urban roads of Berlin drops to 30 km/h or even 15 km/h.The findings of this study show a considerably high increase in trips,passenger hours,and passenger kilometers using public transport modes,when traffic calming links are introduced,the reserve change is observed in private cars trips.Although the speed limits are decreased in inner urban roads in most of the scenarios,the decrease of average travel speed of private cars is not so high as it was expected.Surprisingly,private cars are used for longer distances in all test scenarios.Car drivers seem to use already existed motorways and private road to commute.In simulations,driver compliance to the new speed limits seems to be a determinant factor that is strongly influenced by the design interventions applied in a traffic calming area.
