Parametric study of urban fire spread using an urban fire simulation model with fire department suppression

Although urban conflagrations are rare now, the threat still exists in two situations-following an earthquake and when a wildland fire reaches an urban area. In this paper, we first extend a previously developed urban fire simulation model to include fire department suppression, making it a complete, integrated ignition-spread-suppression model that can now better estimate urban fire risk and help understand the effectiveness of fire department efforts. We then apply this Urban Fire Simulation model (UFS2) to a case study area in California and conduct a parametric study to examine the key factors that influence fire spread and the interactions among them. The results suggest that urban fire spread is highly variable and under the right combination of unlucky but possible circumstances-many ignitions, high wind speeds, and limited water availability-the losses can be very high, much higher than observed in recent earthquakes. In addition to the three factors mentioned, the locations of the ignitions (relative to wind direction and fire breaks), number of engines, and engine arrival times are shown to be important. Strong interactions are evident between wind speed and number of ignitions, and between water availability and number of engines.