Challenges for current quantitative risk assessment (QRA) models to describe explicitly the road tunnel safety level

Abstract

The number of road tunnels in Europe has increased rapidly over the last years. Nevertheless, this increasing number is raising upfront an endogenous problem, which is the severity of accidents that may occur. After the spate of tunnel fires in Europe over the past decade, the European Commission embarked upon a major review of road tunnel safety and launched the Directive 2004/54/EC that sets minimum safety requirements and suggests, apart from the measures imposed based on tunnel characteristics, the implementation of a risk assessment in several cases. As a result, many risk assessment methods have been proposed worldwide, most of them based on quantitative risk assessment (QRA) models. Although QRAs are helpful to address physical aspects and facilities of the infrastructures, current approaches in the road tunnel field have several challenges to meet in order to provide decision-makers with the overall risk picture. Taking into account that QRAs are progressively becoming the selected method to manage tunnel safety and risk, this paper’s purpose is twofold. On the one hand, it aims to inform safety managers and engineers about items which are not adequately handled by current road tunnel QRA models. On the other hand, it aims to suggest potential areas in which improvements should be made. Taking into consideration the challenges and the limitations discussed herein, this paper concludes that QRA models should not be the single criterion for the safety assessment process of these critical infrastructures.