Developing a vulnerability index for road networks under hidrogeological events

Recently, in different countries, the need to manage and predict emergency situations has increased. Road nets and transportation infrastructures are essential to assure the social and economic development of a country, for this reason it is necessary to protect them from calamitous events. The delay in rescue operations during emergency situations, caused by inefficiency of transportation system, can considerably increase the damages. For a long time these topics have been neglected in the design / construction / maintenance of road networks. For this reason it is essential to assess existing risks on road infrastructures before that calamitous events occur, in order to plan appropriate maintenance interventions. The vulnerability assessment of a road network is one of the three fundamental steps towards a comprehensive definition of risk. However this topic has attracted the attention of researchers only recently. The concept of vulnerability has not yet been unambiguously defined and it is possible to find different approaches and methodologies to study road vulnerability. The paper develops a careful analysis of previous researches about the study of road vulnerability. It shows different methodologies and indicators that can be used, these depend on the scale of analysis or the object of analysis. For example, about the scale of analysis, it is different if we analyze the vulnerability a road network (accessibility, connectivity, capacity, reliability ecc. ) or if we study the vulnerability of a part of the road (with specific check lists) or moreover, if we talk about structural vulnerability of bridges, hydraulic works etc. The paper shows how we can use vulnerability indicators to assess the reliability of a road network; these indicators are useful to the Administrators to improve the distribution of the interventions and the economic resources along the entire road network.