This study focuses on the influence of the fuel bed width on the rate of spread. An experimental set-up based on visible cameras combined with image processing was used and a direct linear transformation (DLT) algorithm was developed in order to quantify fire propagation features such as the rate of spread, the fire length, ... The present work gathers results aimed at demonstrating the dependence of the rate of spread on the fire front morphology. A new cellular automaton was developed to better understand the heat transfer mechanisms, investigating in particular the role of radiative transfer.