Risk assessment of dangerous goods in road tunnels CIRO CALIENDO, MARIA LUISA DE GUGLIELMO Department of Civil Engineering University of Salerno Via Giovanni Paolo II, 84084 Fisciano (SA) ITALY ccaliendo@unisa.it, mdeguglielmo@unisa.it Abstract: - An evaluation of the impact due to vehicles transporting dangerous goods on the risk level in road tunnels is presented. Unidirectional tunnels having characteristics in compliance with the European Directive 2004/54 EC were more especially investigated. Different percentages of dangerous goods vehicles (DGVs) considered as part of freight vehicles were analysed. The results expressed in terms of social risk, as F/N curves, or expected value (EV) show that the risk level increases in a linear way with the percentage of DGVs. However longer tunnels present both higher gradients and major risk levels. These results can help us in getting an understanding whether the circulation through tunnels of DGVs should be free, limited to specific time periods (e.g., by night), or forbidden. Key-Words: - Quantitative risk analysis, road tunnels, heavy vehicles, dangerous goods 1 Introduction According to Eurostat [1] the volume of freight carried on Europe’s roads increases continuously. An evaluation of about 39 million freight vehicles circulating on the roads of the EU-28 at the end of 2013 has been estimated, with a rate of 77.8 utility vehicles per 1000 inhabitants. Among the aforementioned vehicles, dangerous goods vehicles (DGVs) have a relevant importance for safety both on roads and in tunnels. Their circulation is governed, from 1957, by European Agreement Concerning the International Carriage of Dangerous Goods by Road (ADR) [2]. In the light of this agreement, each Contracting Party can apply restrictions to the passage of vehicles carrying dangerous goods through tunnels by means of assigning the road tunnel to one of the tunnel categories (from A to E). Category A indicates tunnels with no restriction for the carriage of dangerous goods; while, on the contrary, category E specifies tunnels with restrictions to all type of dangerous goods. The tunnel category, which is based on the consideration that in tunnels the severe accidents can be caused by explosion, release of toxic gas (or volatile toxic liquid) and fire, must be made by competent authority. However, it has to be stressed that, at moment, many countries (e.g., including also Italy) have great difficult to apply restrictions for orographic features, political or social implications, as well as for management problems of tunnels belonging to border roads. Therefore, in lack of the specified category, a tunnel has to be considered free to passage of all type of vehicles. This includes also those carrying dangerous goods, with the legal responsibility of their circulation which is attributed to the Tunnel Management Agency (TMA). For this reason, TMAs need tools for making more appropriate decisions about to limit or forbid that DGVs pass through a tunnel. In this respect, a quantitative risk analysis (QRA) is suitable. The European Parliament and Council in 2004 adopted the European Directive 54/EC [3]. In this Directive, in which minimum safety requirements are reported, is also specified that for tunnels opened to dangerous goods a risk analysis should be carried out to establish if additional safety measures should be implemented. The Italian Ministry of Infrastructure and Transports also adopted the aforementioned Directive [4], and subsequently the Italian Management Agency of National Roads and Motorway (ANAS) [5], has published guidelines including a risk analysis method. Most risk analyses are based on an average value of the percentage of dangerous goods vehicles (DGVs) considered as part of freight vehicles. Indeed, dangerous goods flow is not constant but can vary depending on the type of road (e.g., a road serving nuclear, chemical or petrochemical plants is interested by a higher number of DGVs than a common road) and during the day (e.g., peak WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT Ciro Caliendo, Maria Luisa De Guglielmo E-ISSN: 2224-3496 307 Volume 12, 2016