Comparison <strong>of</strong> F/N curves for 13 tunnels in <strong>Austria</strong>
FRANCE In <strong>France</strong>, so far, quantitative risk analysis <strong>of</strong> dangerous goods transport is required for all new tunnels, except for non-urban tunnels less than 500m if bidirectional, and less than 800m if uni-directional. A simple qualitative approach may be used in o<strong>the</strong>r cases. For tunnels in operation, a <strong>QRA</strong> study is required only when modifications are planned for <strong>the</strong> dangerous goods traffic, or if asked by <strong>the</strong> French authorities. However, after having performed a number <strong>of</strong> <strong>QRA</strong> studies, it was concluded that a criterion based on tunnel length is insufficient to define whe<strong>the</strong>r detailed risk analysis is required (<strong>QRA</strong> study) or not (qualitative study). O<strong>the</strong>r parameters such as <strong>the</strong> traffic characteristics are also important. This can be illustrated by considering a past case study where tunnel was long enough to require a <strong>QRA</strong> study, but <strong>the</strong> DGV traffic was too low to constitute a significant level <strong>of</strong> risk. An Intrinsic Risk (IR) criterion has <strong>the</strong>refore been defined, based on past experience gained using <strong>the</strong> <strong>QRA</strong> model. This criterion corresponds to an Expected Value <strong>of</strong> 0.001 fatalities per year. The Intrinsic Risk is calculated by applying <strong>the</strong> <strong>QRA</strong> model to <strong>the</strong> tunnel itself, taking no account <strong>of</strong> <strong>the</strong> adjacent open sections <strong>of</strong> <strong>the</strong> route. Only <strong>the</strong> eleven dangerous goods scenarios in Table 1, and not <strong>the</strong> two HGV fire scenarios, are considered. If IR > 0.001 for a given tunnel, <strong>the</strong>n a <strong>QRA</strong> study is carried out to compare <strong>the</strong> tunnel and alternative routes. When comparing two routes, with Expected Values, EV1 and EV2, three situations have been defined: • EV1/EV2 < 3 O<strong>the</strong>r criteria are required to make a decision • 3 < EV1/EV2 < 10 A sensitivity study is required • EV1/EV2 > 10 Route 2 should be favoured When EV1/EV2 < 3, <strong>the</strong> following o<strong>the</strong>r criteria are considered: • risk aversion; • accidents without involvement <strong>of</strong> hazardous material; and • route vulnerability from economic and environmental points <strong>of</strong> view. <strong>QRA</strong> studies have now been carried out for about 30 tunnels. Of <strong>the</strong>se, <strong>the</strong>re were 5 cases (19%) with IR < 0.001, 4 cases (15%) with IR » 0.001, and 18 cases (67%) with IR > 0.001. Of <strong>the</strong> <strong>QRA</strong> studies with IR 0.001, <strong>the</strong>re were significant differences between routes in half <strong>of</strong> <strong>the</strong> cases (11 out <strong>of</strong> 22 cases). Of <strong>the</strong>se, <strong>the</strong> tunnel route was found to be less dangerous in 2 cases (18%) and more dangerous than <strong>the</strong> alternative route in 9 cases (82%).