
\conclusions  %% \conclusions[modified heading if necessary]
	The addition of new features and functions for VEIN depends on the availability of data and research publications. The following paragraphs describe some future plans related to specific functions of VEIN.
    
    	It is expected that new features will be added to future versions of VEIN. % and such features may include traffic interpolation functions. In geostatistics research, there are several methods such as krigging, inverse weighted regressions and auto correlated regressions, as shown by \cite{sp1}. Some of these functions could be added in the near future. For instance, one study of vehicular emissions used the Global Moran's Index for interpolating traffic data in Brazil \citep{RequiaJr201532}. 
        The age functions are based on survival equations that are sourced from the National Emissions Inventory of Vehicles report \cite{MMA} and parameterized in \textit{age*} functions. It would be most advantageous to add new survival equations into the age functions. %However, this also depends on the availability of data. %Nevertheless, VEIN allows the option to use any coefficient in the age functions. Furthermore, the user could distribute its traffic data by age of vehicle use with the function \textit{my\_age}. 
	
	The emission factors are another aspect of VEIN that can be enhanced in future versions. They could be sourced from several emissions studies, such as tunnel studies (\cite{perez2014emission}, \cite{martins2006emission}), or others based on traffic situations whereby emissions are sourced from driving cycles (ARTEMIS for example, \cite{andre2004artemis}) or other experimental campaigns \citep{corvalan2003experimental}.  
	
	VEIN's purpose is to serve as a tool for air quality research and environmental management. Since air quality models need detailed emissions species, VEIN was created with the function \textit{speciate}. VEIN will add several new speciations into these functions, such as those in the EMEP/EEA guidelines \citep{copert}. In Brazil, there are several studies of tropospheric ozone, which use speciation of VOC emissions as an input (\cite{acp-2016-1190}, \cite{acp-16-777-2016}). 