Fig. 4

a Physical vulnerability, b functional vulnerability, and c systemic vulnerability of the transport system. The assessment is based on the qualitative levels (L, M, H) of Tables 5, 6 and 7. Nonetheless, each qualitative level is assigned a value (1, 2, 3; Tables 5, 6 and 7) in order to obtain a quantitative classification (indicated with the three different colours from rose to dark violet). Values associated with the three categories are also indicated in legend