Urban traffic emissions estimates using coupled models

The primary sources of air pollutants in urban areas are mobile (vehicles). In addition to fleet diversity, Brazilian vehicles use different types of fuels and various technologies to control emissions. Among the tools developed to assist the implementation of solutions that minimize the negative impacts of vehicular pollutant emissions, there are traffic, emission, and air quality models. Therefore, estimating the effects of vehicular emissions using computer modeling is a research opportunity for densely populated urban areas with representative fleets. Considering the context, the main objective of this work was to estimate the vehicle emissions by coupling statistical models to the emissions model using radar and count vehicle database. Thus, to improve numerical modeling techniques, it was developed a methodology for performing traffic information transfers to air quality models. Belo Horizonte (Minas Gerais), a city located in an area of 331 km2 and with a population of approximately 2.5 million inhabitants, was selected to develop this study. The periodic behavior of traffic on urban roads and the characteristic curves of this behavior by vehicle category were estimated based on flow count data (radars and manual counts). Different statistical models were used to calculate the spatialization of vehicle flow. The result showed that the mixed model normal-neighbor was suitable for the flow spatialization in urban roads. The result of flow data spatialization on the city was the input data for the quantification of emissions by vehicle category and fuel type, using the Brazilian Vehicle Emissions Inventories – VEIN. Current and future scenarios were modeled with fleet reduction strategies to calculate the impact on vehicle emission reduction. The evaluation scenarios showed that actions such as the implementation of road space rationing and vehicle inspection program, the removal of the over 30-year-old fleet from urban roads, the replacement of the bus fleet by electric vehicles lead to reductions of up to 44% in CO emissions, 42% of NOx and 38% of MP2.5. The implementation of the strategies suggested adding the non-use of the private vehicle, as well as the construction of quality public transport infrastructures (subway lines and bike paths connecting the city regions), can contribute satisfactorily to improve the air quality in Belo Horizonte.