## 3 Materials and Methods  
The research and analyses are based on the currently valid CBA methodologies for assessing transport projects in the Slovak Republic, the Czech Republic, Hungary, and Austria. These methodologies contain specific GHG emission characteristics, emission factors, and unit costs of climate change, which are used in the analytical and research parts of this paper. * The values of GHG emission factors and densities of selected fuels according to the _Handbook of Emission Factors for Road Transport_ (HBEFA Methodology), version 4.2.2 were also used [53]. * The unit costs according to the _Handbook on the External Costs of Transport_, version 2019, January 2019--V1.1, European Commission [54], were used to determine the financial value of GHG emissions. * Emission and energy factors for greenhouse gas emissions were calculated according to ISO 14083 Greenhouse gases--Quantification and reporting of greenhouse gas emissions arising from transport chain operations, ISO--International Organization for Standardization, valid from March 2023 [55]. * Emission and energy factors for greenhouse gas emissions were calculated according to STN EN 16258 Methodology for the calculation and declaration of energy consumption and greenhouse gas emissions from transport services (freight and passenger transport), Slovak Institute of Technical Standardization, September 2013 [56]. CBA Methodology in the Slovak Republic--Characteristics of Greenhouse Gas Emissions, Their Production, and Economic Value  
According to the CBA methodology in the Slovak Republic, the relevant greenhouse gases from transport (arising from the combustion of fuels) to be considered in the CBA are carbon dioxide (CO\({}_{2}\)), methane (CH\({}_{4}\)), and nitrous oxide (N\({}_{2}\)O). As a first step, the processor should determine the amount (ideally in tons) of greenhouse gases emitted based on fuel consumption data for vehicles using traditional fuels (petrol and diesel) and emission factors from electricity consumption (in the case of electric drives). Emission factors for different vehicle categories are in Table 1 below. The density of the different fuels given in the CBA methodology in the Slovak Republic, as well as the emission factors according to the CBA methodology in the Slovak Republic, were used to calculate the amount of greenhouse gases emitted by petrol and diesel vehicles correctly. The data source for the CBA methodology in the Slovak Republic is the EEA. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Vehicle Category (Fuel)**} & \multicolumn{3}{c}{**Polluting Substance**} \\ \cline{2-4}  & **CO\({}_{2}\)** & **CH\({}_{4}\)** & **N\({}_{2}\)O** \\ \hline Passenger vehicles (petrol) & 3180 & 1.09 & 0.206 \\ Passenger vehicles (diesel) & 3140 & 0.23 & 0.087 \\ Light-goods vehicles (diesel) & 3140 & 0.16 & 0.056 \\ Heavy-goods vehicles, medium goods vehicles, and buses (diesel) & 3140 & 0.27 & 0.051 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Emission factors (g/kg) of road vehicles (conventional fuels) [57,58]. Based on the content of the CBA methodology in the Slovak Republic, we have defined relationships for the calculation of the quantity of fuel consumed, the quantity of pollutants, and the cost of pollutants in Supplementary Materials. The quantity of fuel consumed I (by mass) is calculated using Equation (S1) from Supplementary Materials. The amount of greenhouse gases from road transport i is calculated using Equation (1):  
\[AGHG\ RT_{i}=AFC\ M_{i}\ *EF\ GHG_{ik} \tag{1}\]  
where  
\(AGHG\ RT_{i}\) is the amount of greenhouse gas from road transport. \(EF\ GHG_{ik}\) is the emission factor of the i-th type of fuel of the k-th type of GHG. Substituting Equation (S1) into Equation (S2), we obtain Equation (S3) from Supplementary Materials.