By conducting fire experiments in double-decker coaches it was observed that there was no formation of a stable smoke layer in the upper compartment (level) if the location of origin is the lower deck. The smoke rises over the stairs, cools down and as a result loses its buoyancy. When the smoke reaches the upper level it disperses over the whole height. Consequently, the passengers in the upper level are exposed to toxic fire effluents directly after ignition in the lower level. This phenomenon was simulated by the computational fluid dynamic model FDS. Because different concepts for the interior design of double-decker coaches exist, the possible positions of glass partitions as barriers can vary. On the one hand the levels can be partitioned into several cabins, e.g. one cabin for bicycles, one for first or one for economy class. On the other hand the levels can be divided by the staircases. Those different barriers have an essential influence on the dispersion behaviour of the smoke. By using FDS the effects of different design configurations on the smoke movement are examined. Furthermore, different ventilation scenarios when the train halts are considered, e.g. the possibility that passengers destroy the windows in the upper level to enable an inflow of fresh air. The influence of opened windows is included, as well as the use of natural heat and smoke vents. Therefore, advantages and disadvantages of different combinations of the vents and interior design configurations are discussed.
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