## 4 Discussion and Concluding Remarks  
This paper shows the results of a study aimed at assessing--at the municipal scale--the level of risk (or attention required) of stretches of road exposed to the activity of existing or potential slow-moving landslides. The study was conducted by defining and applying a territorial conceptual model, and thus a procedure that can be implemented in GIS, in two study areas in the municipalities of Vaglio Basilicata and Trivigno (Basilicata region, southern Italy). The investigated road networks represent strategic nodes of the road system in these territories, as they connect a strategic highway located in the valley floor of the main river of the area to the two urban centers. Adopting a matrix-based approach, the procedure developed herein combines the following data: landslide inventories, thematic information available over the entire investigated municipal territories, surface displacement remote sensing data and road damage data available for the investigated roads. The analyses highlight that the investigated road networks are affected by widespread (real or potential) landslide risk in both study areas. In Vaglio Basilicata, about 9.73 km (33%) of roads are classified as being at high or medium risk and about 10.58 km (36%) as requiring high or medium attention. In Trivigno, about 9.73 km (60%) of roads are classified as high or medium risk and about 4.36 km (26%) as high or medium attention. Looking at the access routes from/to the Basentana highway and the city centers, i.e., four for Vaglio Basilicata, two for Trivigno (see Figure 2), each alternative route is characterized by one or more road stretches at high or medium risk or attention. These classification results of the road networks at the municipal scale allow the identification of the road stretches where mitigation measures (for road stretches classified at high and medium risk) or further investigation (for road stretches classified at high and medium attention) may be necessary. Out of a total of 213 road stretches in Vaglio Basilicata, 85 stretches at high and medium risk and 75 road stretches requiring high and medium attention are identified. Similarly, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Study Area**} & \multicolumn{3}{c}{**Road Stretches at Risk [km]**} & \multicolumn{3}{c}{**Road Stretches at Attention [km]**} \\ \cline{2-9}  & **H** & **M** & **L** & **VL** & **H** & **M** & **L** & **VL** \\ \hline Vaglio & 1.99 & 7.74 & 7.34 & 0.19 & 3.47 & 7.11 & 1.48 & 0.10 \\ Basilicata & (24) & (61) & (36) & (2) & (32) & (43) & (13) & (2) \\ Trivigno & 1.47 & 8.67 & 1.15 & \(-\) & 1.97 & 2.39 & 1.21 & 0.07 \\  & (14) & (32) & (17) & (\(-\)) & (24) & (33) & (13) & (1) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Total lengths of road stretches classified at high (H), medium (M), low (L) and very low (VL) risk (or attention) in Vaglio Basilicata and Trivigno. The number of road stretches are reported in parentheses. out of a total of 134 road stretches in Trivigno, 57 stretches at high and medium risk and 46 stretches at high and medium attention are identified. It is important to highlight that the classification results obtained in the two study areas must be interpreted considering the municipal scale of the analysis--thus the procedure does not aim at defining risk or attention levels locally--and that the sources of uncertainty affecting the final accuracy of the results are many.