This work presents an enhanced version of a simple model of surface fire spread, already reported in [J.H. Balbi, J.L. Rossi, T. Marcelli, P.A. Santoni, Combust. Sci. Technol. 178 (2007) 2511-2537]. The simplicity of the original model was preserved and the "faster than real time" simulation speed was retained. The empirical relations were replaced by physical equations using flame geometry considerations, and the model now uses only two model parameters. It was tested and validated using a large set of laboratory and field scale experiments, carried out across fuel beds under different slope and wind conditions. Finally, the model was implemented as the physical core of a wildfire simulation tool for field scale fires and the case of a large wildfire was successfully treated as a first code evaluation. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.