DRIVING BEHAVIOR EFFECTS ON THE POLLUTANTS EMISSIONS IN RURAL HIGHWAYS: A DRIVING SIMULATOR STUDY

The air pollution has become a sensitive topic in the international scene, leading to the definition of laws and regulations. According to several publications by European Commissions, such as the White Paper, the role of transport within the framework of air quality improvement is clear. It is therefore necessary to provide tools that can give to planners real opportunities to look at different strategies to be put in place. There is a need to refer to models that are more reliable and precise, due to the higher demand for the reduction of pollutants dictated by the environmental requirements of pursuing sustainable development. Currently, mainly two groups of emission models are available: the former is represented by the static or “standard” models, in which the amount of pollutant is computed as a function of average parameters; the latter is represented by the dynamic models, where the amount of pollutant is computed as a function of instantaneous parameter, such as instantaneous speed or acceleration. In the last years the traffic increase has significantly changed the actual flow conditions, producing a strong rise of interferences. As this facet affects the operating condition of each vehicle, the use of a standard emission models at high traffic interference can lead to some inaccuracies. This aspect is especially influential in rural or urban areas, where may occur “stop&go” phenomena, so the average speed cannot be considered as a significant parameter of the emissions. In such cases, instantaneous emission models introduce deeper capabilities; essentially, the pollutant prediction is directly tied to the engine vehicle operation point in real-like traffic condition. However, this approach requires a large amount of input data (i.e. video recordings or remote sensing analysis), which are not always available. Starting by the experience developed and presented in RSS2013 in the field of freeway, and in order to cope the aforementioned difficulty, the present study is based on an integrated simulation tool. Emissions from road traffic are simulated through a dynamic model, whose input data are obtained by the output of virtual reality simulation. This method allows taking the influence of users driving behaviors in different geometrical and flow conditions into account. Indeed, the analysis took advantage of the experiments carried out in the vehicle virtual reality laboratory: on typical rural highway geometry, different flow conditions have been simulated. Investigations have highlighted the dependence of emissions and fuel consumption on drivers’ behavior. The comparison between a gasoline and a diesel compact passenger car in terms of pollutant emissions and fuel consumption has been also reported.