This paper presents the coupling of a stochastic operation time model to real-scale fire simulations in a major incident. The chosen scenario was a tanker train accident leading to a fire in a city center railway underpass. The underpass is covered with a deck, ontop of which is built a sporting arena and a shopping centre. The fire scenario was a flowing gasoline fire with a heat release rate of 200 MW. In this case, the purpose of the rescue service operation is to provide sufficient cooling capacity in order to prevent structural damage to the deck above the train, as well as to prevent a BLEVE incident. The stochastic operation time model was used to describe the time evolution of the rescue service activities from time zero (fire ignition) up to a point in time when sufficient resources are in action on the site of the incident. The output from the simulation was the accumulation of rescue service resources (water cannons) as a function of time. Numerical fire simulations were conducted using the Fire Dynamics Simulator (FDS) for evaluating the cooling performance of the cannons as a function of number and placement strategy. By combining the stochastic operation time model with the results of the numerical fire simulations, the cumulative cooling capability of the rescue service operation could be quantitatively determined as a function of time. For comparison purposes, the cooling effectiveness of water cannons were compared to that of sprinkler systems based on either conventional or spray sprinklers.
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