# Beyond Static Estimates: Dynamic Simulation of Fire-Evacuation Interaction in Historical Districts
## 4 Discussions
### Bridging Dynamic Interactions Between Evacuation and Building Environment Changes in Disasters  
A major limitation of previous research lies in its failure to dynamically capture the evolving interactions between changes in the built environment and evacuation behavior during fires in historical districts. To address this gap, this study introduces a three-stage temporal framework that reflects the progression of fire and its impacts on evacuation, while considering the role of evacuation policy. In the first stage (0-10 min post-ignition), the spatial extent of fire impact remains limited and mostly concentrated around the ignition point. Nevertheless, it significantly affects nearby evacuees, especially by inducing detours, which disproportionately burden vulnerable groups such as the elderly and mobility-impaired individuals. At this stage, fire dynamics can largely be simplified; attention should instead focus on analyzing evacuation route changes based on estimated high-temperature zones and behavior patterns. The second stage (11-30 min post-ignition) is characterized by a near-radial expansion of both direct (flames) and indirect (heat, smoke) fire effects, progressing slowly at an average rate of 0.37-0.47 m/s--slower than human walking speed. Thus, evacuation is mainly influenced by static environmental conditions such as the number of available exits, road width and connectivity, and the location of ignition. Of particular concern during this stage is the risk of congestion on highly connected arterial roads, especially when long pre-warning distances are applied. Simultaneously, congestion at evacuation destinations becomes increasingly salient, necessitating careful consideration of entrance widths and shelter capacity. In this phase, nonlinear fire dynamics can still be reasonably simplified; the primary analytical focus should instead be on how evacuation strategies influence internal congestion and access bottlenecks near shelter entrances. The third stage (after 30 min) involves fewer evacuees remaining in the district. At this point, attention should shift toward assessing fire-induced structural damage to the built environment rather than active evacuation behavior. While fire dynamics can no longer be ignored, their impact on ongoing evacuation activities becomes secondary. This phased framework improves both analytical precision and computational efficiency, as simplifications can be applied to selected components of fire and behavioral modeling at each stage. Furthermore, the use of clearly defined metrics facilitates targeted intervention strategies. Based on this conceptual model, we argue that the unique nature of built environment transformation in historical districts requires deeper investigation--particularly in the second stage--into the compatibility between evacuation strategies and physical evacuation conditions. While prior research has generally considered expanding district exit widths and increasing internal street widths within historical districts to be the most effective methods for improving evacuation efficiency, this study challenges that assumption in the context of historical districts. For instance, studies on school evacuations frequently highlight the importance of early warning and alarm systems for casualty reduction. However, our findings suggest that such strategies are only effective when the evacuation traffic system possesses adequate capacity. In the studied historical district, evacuation distances below 75 m were found to trap evacuees in cul-de-sacs. Yet, increasing the evacuation distance often leads to a linear increase in congestion points and evacuation duration, resulting in a structural contradiction between \"faster alerts\" and \"faster congestion\". While space constraints preclude an exhaustive exploration of all scenarios, current results strongly suggest that a major contributing factor is the inadequate width of primary streets within the historical district.