As with any complex fuel assembly configuration, modeling a goods-vehicle fire using fire dynamics simulator (FDS) to estimate the heat release rate in a tunnel is a challenging task. The present study involves the use of heat release rate curves taken from the Runehamar tunnel fire experiment T1 to ‘calibrate’ the heat release rate curve predicted using FDS 4.0.7. The article presents a simplified geometric representation of burning wood and plastic pallets and then illustrates that an FDS simulation of this representation is able to reproduce a reasonable estimate of the fire growth characteristics in the tunnel. The effects of the assumptions made in simplifying the fuel array are considered in order to calibrate these simulations. Finally, the article shows how the fire growth might change if conditions in the tunnel were varied.