The present paper investigates a travelling fire scenario in an elongated structure (Length 18 m x width 6 m x height 3 m) with a controlled fire source of six pans filled with diesel (width 4 m x length 0.5 m). The fire spread is controlled manually by initiating fires subsequently in the pools. Fire Dynamics Simulator (FDS) is used to a-priori investigate variations in geometry, material data and fire load whereas simulations using the final design were performed after the test. The input to the model beside fire source and geometry are thermal material data. The FDS simulation were used to determine the appropriate size of the downstands (2 m from the ceiling in the final design) on the side to create a sufficiently one-dimensional fire spread. The post test simulations indicate that although there are a lot of variations not included in the model similar results were obtained as in the test.