Traffic flow impacts on the environment along urban streets under mixed traffic conditions in Al-Najaf city

Abstract

With the increase in population and urban mobilization worldwide, the rapid urbanization of Najaf has led to a massive increase in road traffic. Automobile traffic is now regarded as one of the most significant sources of air pollution in Iraq, with a considerable impact on air quality. This study conducted measurements in a selected urban-road network in Al-Najaf city in Iraq that witnessed a high traffic flow index to measure vehicle emissions and study the correlation between the traffic flow and emissions in this network during peak hours. Priority parameters were measured such as: “Carbon dioxide,” “Carbon monoxide,” “Nitrogen dioxide,” “Nitrogen monoxide,” “Sulfur dioxide,” and other parameters also monitored, including temperature, the direction of the wind, the velocity of wind, and the traffic parameters. It shows that the high heterogeneous traffic flow increases pollutants produced by vehicles. At the same time, it decreases substantially with the decrease in flow and speed. The highest level of Carbon dioxide was: 486ppm, 466ppm, and 447 ppm at peak hours when high traffic density. Also, the highest concentration of Co was 8.22, 4.52, and 3.98 ppm in all locations indexed in the moderate zone, No2 and SoD exceeding EPA levels marking the index in the (very unhealthy) zone. The correlation analysis showed a good and very good linear regression model between CO, CO2, and volume with average vehicle speed. According to these results, the pollution in Najaf due to transportation is significant, with potentially serious health repercussions.