# System Dynamics Modeling for Estimating the Locations of Road Icing Using GIS
## 4 Discussion
\begin{table}
\begin{tabular}{c|c c|c c|c c|c c} \hline \hline \multicolumn{2}{c}{**Case**} & \multicolumn{2}{c}{**Road Temperature**} & \multicolumn{2}{c}{**Road Moisture**} & \multicolumn{2}{c}{**Road Icing**} & \multicolumn{2}{c}{**GIS simulation**} \\ \hline  & **Estimation** & **Form** & **Estimation** & **Form** & **Estimation** & **Form** & **Performance** & **Form** \\ \hline \multirow{2}{*}{Case 1� [19]} & \multirow{2}{*}{\(\surd\)} & Occurrence/non- & \multirow{2}{*}{–} & \multirow{2}{*}{–} & \multirow{2}{*}{–} & \multirow{2}{*}{–} & \multirow{2}{*}{–} & \multirow{2}{*}{–} \\ Case 2� [20] & & & & & & & & \\ Case 3� [21] & & & & & & & & \\ Case 4� [22] & & & & & & & & \\ Case 5� [23] & & & & & & & & \\ \hline \multirow{3}{*}{This study} & \multirow{3}{*}{\(\surd\)} & Value, location & \multirow{3}{*}{\(\surd\)} & Value, & Value, & \multirow{3}{*}{–} & \multirow{3}{*}{–} & \multirow{3}{*}{–} \\  & information & & location & location & location & location & & GIS \\ \cline{1-1}  & & information & & information & & information & & layer \\ \hline \hline \end{tabular} \(\surd\) performed, – not performed.  
\end{table} 
Table 7: Comparison of the results of this study with previous cases. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Section Name**} & \multicolumn{1}{c}{**Management**} & \multirow{2}{*}{**Line**} & \multicolumn{1}{c}{**Freezing Accidents**} & \multicolumn{1}{c}{**Regional**} & \multicolumn{1}{c}{**Minimum**} \\  & **Number** & & & **(Morning)** & **Characteristics** & **Temperature** \\ \hline \multirow{2}{*}{Jeobchijae (1)} & 287 & Honam highway & \multirow{2}{*}{3 to 4} & \multirow{2}{*}{Morning shading} & \multirow{2}{*}{–3–0 \({}^{\circ}\)C} \\  & & line 25 & & & & \\ \multirow{2}{*}{Jeobchijae (2)} & 288 & Honam highway & \multirow{2}{*}{1 to 2} & \multirow{2}{*}{Morning shading} & \multirow{2}{*}{–3–0 \({}^{\circ}\)C} \\  & & line 25 & & & & \\ \multirow{2}{*}{[PERSON] (1)} & 289 & Honam highway & \multirow{2}{*}{1 to 2} & \multirow{2}{*}{Morning shading} & \multirow{2}{*}{–3–0 \({}^{\circ}\)C} \\  & & line 25 & & & \\ \multirow{2}{*}{[PERSON] (2)} & 290 & Honam highway & \multirow{2}{*}{1 to 2} & \multirow{2}{*}{Morning shading} & \multirow{2}{*}{–3–0 \({}^{\circ}\)C} \\  & & line 25 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: List of sections vulnerable to freezing traffic accidents in Honam highway in Suncheon. probability that a type 1 error is allowed), the null hypothesis is rejected and the research hypothesis is adopted. The null and alternative hypotheses were established as follows, and the adoption of the alternative hypothesis was confirmed by calculating the P-value of each section and comparing it with 0.05 (significance level) [56]. * H0: (null hypothesis) the model does not generate thin ice in the vulnerable area (RI < 3 g/m3). * H1: (alternative hypothesis) the model generates thin ice in the vulnerable area (RI >= 3 g/m3). For null and alternative hypothesis testing, the \(p\)-value was calculated by conducting the upper tailed test on the road icing formed under conditions below 1 \({}^{\circ}\)C after the occurrence of freezing rain. The formula to obtain the Z-score that standardized the performance value, X, is shown in Equation (20). X is the variable related to the amount of freezing roads generated, \(\mu\) is the average amount, \(\sigma\) is the standard deviation, and n is the number of variables [56]. \[Z=\frac{X\ -\ \mu}{\frac{\sigma}{\sqrt{n}}} \tag{20}\]  
When the \(p\)-value was calculated using the Z-score value in Table 9, the \(p\)-value was lower than 0.05 in the four sections, so the null hypothesis was rejected and the alternative hypothesis was adopted. In the upper tailed test results, the model estimated the amount of road icing generated in the vulnerable sections where freezing accidents occurred, thereby verifying the validity of the model. Figure 13: Map of the sections vulnerable to freezing traffic accidents in Honam highway in Suncheon (Jeobchijaei, 2, Ssangamjae1, 2).