Road User Vulnerability Indexing in Safety Applications: An Alternative View to ETSI

An Intelligent Transportation System (ITS) safety application aims to protect road users (RUs) from hazards, mainly collisions leading to fatalities. Fortunately, organizations such as the European Telecommunications Standards Institute (ETSI) have been standardizing services and requirements that can expedite the real world deployment of these applications. However, this approach has limitations, particularly in their definition of vulnerability. Vulnerability classification shouldn't be based on a simplistic binary definition, but rather on a complex and rich concept. Hence, the aim of this paper is to propose an alternative approach to the definition of vulnerability. This methodology addresses vulnerability classification using a parametrization system comprising four index values that encompass different but complementary perspectives. Static vulnerability (considers the technological and natural characteristics of the RU that induce him to be vulnerable or to pose a threat to others), relative vulnerability (considers the challenge that arises from a collision between a RU and an opponent), and contextual vulnerability (relates to the relative vulnerability and the variables of the scenario in question). The proposed fuzzy-based methodology culminates in the establishment of four vulnerability indexes that more effectively measure the RU vulnerabilities, thus helping in sharpening the definition of safety applications requirements.