## 4 Discussion of the Results  
The seismic events that affected Central Italy in August and October 2016 are among the strongest earthquakes that have happened in that area. Due to the seismic events of 24 August, Amatrice suffered the most extensive in terms of casualties and damage to structures, while the October earthquakes did not cause casualties, because people were already evacuated from damaged houses due to previous seismic events. Based on a field survey performed in Amatrice on 12 September 2016, several authors [20] developed a detailed map of the damage distribution resulting from the seismic events of 24 August. According to these authors, during the first seismic event (the main shock at 3:36 a.m.), the accelerometric station located in the municipality of Amatrice (AMT) recorded a PGA of 0.87 g along the EW component. The AMT seismic station was located at approximately 450 m from the town center and 8.5 km from the epicenter. It was therefore very close to AC1 and AC2 (Figure 11) and consequently, the same _IM_ levels could be considered in the analysis. The map shown in Figure 12 was elaborated from satellite images taken on 25 August [25]. Consistent with the aforementioned authors [20], it shows that along Corso Umberto I, numerous buildings were damaged or collapsed, which caused the complete blockage of AC1 and AC2.  
Figure 10: Fragility curve in terms of probability of opening for (**a**) AC1 and (**b**) AC2.  
Figure 9: Fragility curve in terms of probability of closure for (**a**) AC1 and (**b**) AC2.  
In this study, only the first seismic event (PGA = 0.87 g) was considered, and the cumulative damage effects were neglected. However, based on the literature [20], the damage could be attributed in large part to the first event. As shown in Figure 13, with the PGA value of 0.87 g on the probability axis of the fragility curves developed for the case study, there was a 93% probability that the road  
Figure 11: Location of Amatrice (AMT) seismic station and road network segments individuation.  
Figure 12: Map of damage along Corso Umberto I [25].  
was blocked and, consequently, only a 7% probability that the road was open for the passage of emergency vehicles. Therefore, the proposed methodology provided a good interpretation of the real data concerning the case examined. The results of the validation carried out slightly underestimated the probability of closure due to the damage accumulated after the main shock.  
In order to evaluate the operational efficiency of the emergency management system identified by the LCE analysis through a network of nodes and arcs, it is therefore possible to associate for each node the fragility curve defined for the building (for example using the SMAV methodology [26; 27]), and for each urban arc, the fragility curve constructed with the proposed methodology.  
The developed fragility curves are defined in terms of PGA following the _IM_ values used for the vulnerability functions of buildings. Through the proposed procedure, the fragility curves of the road network segments can be constructed with other _IM_s (Housner Intensity, Arias Intensity, etc.) by assigning different vulnerability functions.