Probability of large fire in a road tunnel; A Bayesian approach

Article 13 of the EU Directive on minimum safety requirements for tunnels in the Trans-European Road Network states that a “risk analysis, where necessary, shall be carried out” [1]. In the Netherlands, the risk of death for road users in a tunnel (internal risk) is calculated with a model for quantitative risk analysis, which is called “QRA-tunnels”. The probability of fire that has been used in the model was expected to be too high compared to the probability of fire based on statistics [2]. In this paper a Bayesian approach is presented based on a research study enabling the calculation of the probability of a large fire in a road tunnel [3]. The calculations result in a lower probability of a large fire, enabling QRA-tunnels to be adapted.