SIMPLIFIED METHOD FOR RISK EVALUATION IN UNIDIRECTIONAL ROAD TUNNELS RELATED TO DANGEROUS GOODS VEHICLES

A simplified method for estimating the risk level in unidirectional road tunnels is presented in this paper. It provides the estimation of the risk level, expressed in terms of the expected value EV, as a function of the tunnel length (L), the annual average daily traffic per lane (AADT), the percentage both of heavy goods vehicles (HGVs) and dangerous goods vehicles (DGVs). The method proposed might support Tunnels Management Agencies (TMAs) in making more appropriate decisions about the strategies of traffic control when the risk due to peak hours of traffic volume, including more especially dangerous goods vehicles, is considered to be excessive compared to normal standards of safety in tunnels. In this respect, in order to reduce the risk level, TMAs could permit the transit of dangerous goods vehicles through tunnel by night, and/or under escort, or an alternative route running completely in open air could be tested.