Verification and Validation of the ARTU (Tunnel Fire Risk analysis) tool

This report presents the results of a set of verification and validation tests of a probabilistic risk assessment tool, named ARTU (Italian acronym for Risk Analysis in Tunnels), for road tunnel fire safety. This is performed along with a literature review to identify key factors that affect the tunnel fire risk along with inputs for the risk assessment tool. To perform the validation of the 1D fluid-dynamics representation within the tool, five full-scale experimental data sets from experiments made in the Second Benelux tunnel in year 2000-2001 were used as a benchmark. Simulations with the Fire Dynamics Simulator (FDS) were used to facilitate the validation. To perform the verification of the key sub-models of the evacuation modelling module and the probabilistic risk analysis calculations, hand calculations of different ideal cases were compared to the results from the tool. The probabilistic analysis aims at calculating an FN-curve (cumulative frequency/number of fatalities) for the tunnel under analysis. The verification of sub-models within the evacuation modelling has shown that the tool gives reasonable, most often conservative results with a margin of error within the order of -13 % and +22 %. The 1D fluid dynamics part gives results that are conservative in four out of five cases. The verification of the probabilistic risk analysis gives results in line with the expected calculated values, with a margin of error within +2 %