A key strategy for successful access management is the adoption of driveway spacing guidelines that consider both safety and operations.The goal is to provide sufficient distance from one driveway to the next so that ...A key strategy for successful access management is the adoption of driveway spacing guidelines that consider both safety and operations.The goal is to provide sufficient distance from one driveway to the next so that drivers can perceive and react to the conditions at each potential conflict point in succession.State DOTs across the country have adopted different driveway spacing standards that vary according to the access class and characteristics of the adjacent roadway,such as type of roadway,posted speed limit,and traffic volume.Utilizing the VISSIM microscopic traffic simulation tool and FHWA’s Surrogate Safety Assessment Model(SSAM),this research examined safety implications of four different driveway spacing policies representing 13 states.The analysis involved calibrating the VISSIM model for an arterial roadway corridor in West Columbia,SC,and then using the calibrated model to simulate various operational changes to the corridor,including speed limits,traffic volumes,and the associated minimum driveway spacing criteria for the four different policies.SSAM was used to analyze vehicle trajectories derived from VISSIM to determine the number of conflict points.Experimental results indicate that posted speed limit and traffic volume are the primary impact factors for driveway safety,and thus,these parameters should be considered in establishing minimum driveway spacing.Findings from this study indicate that there are significant differences in safety impacts between the different driveway spacing policies adopted by various state DOTs.展开更多
Air quality is a critical factor in maintaining health and well-being, influencing both current conditions and future outcomes. Hospitals are one of the sensitive areas of our society, for they are built as sanctuarie...Air quality is a critical factor in maintaining health and well-being, influencing both current conditions and future outcomes. Hospitals are one of the sensitive areas of our society, for they are built as sanctuaries for treatment and recovery, making the quality of paramount importance. This study investigates the impact of traffic-related emissions on indoor air quality within a Level 5 Hospital outpatient ward. Measurements were taken over five consecutive days, revealing that while CO2 levels generally remained within safe limits, there were instances where concentrations exceeded 3000 ppm, categorizing them as “Hazardous.” Notably, particulate matter (PM2.5 and PM10) levels fluctuated significantly, with peak concentrations observed during working hours correlating with increased vehicle activity. The data indicated that PM2.5 levels reached as high as 75 µg/m3, with 91.68% of recorded values exceeding the World Health Organization’s (WHO) and Environmental Protection Agency 24-hour mean threshold of 25 µg/m3. Similarly, PM10 concentrations peaked at 120 µg/m3, with 61.19% of values surpassing the WHO threshold of 50 µg/m3, both of which pose serious health risks, particularly to vulnerable populations such as pregnant women, infants, and the elderly. Additionally, the study highlighted the critical role of wind direction in pollutant dispersion, with specific patterns contributing to elevated indoor concentrations. These findings underscore the urgent need for targeted interventions and proactive air quality management strategies in healthcare facilities, including the strategic design of hospital wards away from primary emission sources and the promotion of electric vehicle use to mitigate traffic-related emissions.展开更多
Conflicts are common phenomena in the field of traffic engineering, while are also the main cause of all the traffic problems. The vehicle access driveway of large shopping mall is often the conflict area of urban roa...Conflicts are common phenomena in the field of traffic engineering, while are also the main cause of all the traffic problems. The vehicle access driveway of large shopping mall is often the conflict area of urban roads, traffic engineers and city managers face a great challenge as to make the traffic enter and exit the shopping mall safely and or-derly. This paper studies the issues of access management of large shopping mall with a focus on Carrefour shopping mall in Shuangjin district, Beijing. This shopping mall attracts and generates lots of traffic during peak hours, those huge numbers of vehicles come in and out of the shopping mall through the access driveway, resulting in a lot of conflicts to the urban road traffic flow and deteriorating highly smooth movement of traffic on the urban roadway. The impacts of the existing design and layout of access driveway on surrounding traffic operation are also studied in this paper. Some countermeasure of improvements had proposed to decrease traffic conflicts and make sure that the traffic conditions get better off, all the improvement countermeasures are based on the access management principles. Results from this study can be a good reference on other similar driveways at large shopping mall areas.展开更多
文摘A key strategy for successful access management is the adoption of driveway spacing guidelines that consider both safety and operations.The goal is to provide sufficient distance from one driveway to the next so that drivers can perceive and react to the conditions at each potential conflict point in succession.State DOTs across the country have adopted different driveway spacing standards that vary according to the access class and characteristics of the adjacent roadway,such as type of roadway,posted speed limit,and traffic volume.Utilizing the VISSIM microscopic traffic simulation tool and FHWA’s Surrogate Safety Assessment Model(SSAM),this research examined safety implications of four different driveway spacing policies representing 13 states.The analysis involved calibrating the VISSIM model for an arterial roadway corridor in West Columbia,SC,and then using the calibrated model to simulate various operational changes to the corridor,including speed limits,traffic volumes,and the associated minimum driveway spacing criteria for the four different policies.SSAM was used to analyze vehicle trajectories derived from VISSIM to determine the number of conflict points.Experimental results indicate that posted speed limit and traffic volume are the primary impact factors for driveway safety,and thus,these parameters should be considered in establishing minimum driveway spacing.Findings from this study indicate that there are significant differences in safety impacts between the different driveway spacing policies adopted by various state DOTs.
文摘Air quality is a critical factor in maintaining health and well-being, influencing both current conditions and future outcomes. Hospitals are one of the sensitive areas of our society, for they are built as sanctuaries for treatment and recovery, making the quality of paramount importance. This study investigates the impact of traffic-related emissions on indoor air quality within a Level 5 Hospital outpatient ward. Measurements were taken over five consecutive days, revealing that while CO2 levels generally remained within safe limits, there were instances where concentrations exceeded 3000 ppm, categorizing them as “Hazardous.” Notably, particulate matter (PM2.5 and PM10) levels fluctuated significantly, with peak concentrations observed during working hours correlating with increased vehicle activity. The data indicated that PM2.5 levels reached as high as 75 µg/m3, with 91.68% of recorded values exceeding the World Health Organization’s (WHO) and Environmental Protection Agency 24-hour mean threshold of 25 µg/m3. Similarly, PM10 concentrations peaked at 120 µg/m3, with 61.19% of values surpassing the WHO threshold of 50 µg/m3, both of which pose serious health risks, particularly to vulnerable populations such as pregnant women, infants, and the elderly. Additionally, the study highlighted the critical role of wind direction in pollutant dispersion, with specific patterns contributing to elevated indoor concentrations. These findings underscore the urgent need for targeted interventions and proactive air quality management strategies in healthcare facilities, including the strategic design of hospital wards away from primary emission sources and the promotion of electric vehicle use to mitigate traffic-related emissions.
文摘Conflicts are common phenomena in the field of traffic engineering, while are also the main cause of all the traffic problems. The vehicle access driveway of large shopping mall is often the conflict area of urban roads, traffic engineers and city managers face a great challenge as to make the traffic enter and exit the shopping mall safely and or-derly. This paper studies the issues of access management of large shopping mall with a focus on Carrefour shopping mall in Shuangjin district, Beijing. This shopping mall attracts and generates lots of traffic during peak hours, those huge numbers of vehicles come in and out of the shopping mall through the access driveway, resulting in a lot of conflicts to the urban road traffic flow and deteriorating highly smooth movement of traffic on the urban roadway. The impacts of the existing design and layout of access driveway on surrounding traffic operation are also studied in this paper. Some countermeasure of improvements had proposed to decrease traffic conflicts and make sure that the traffic conditions get better off, all the improvement countermeasures are based on the access management principles. Results from this study can be a good reference on other similar driveways at large shopping mall areas.
