# Beyond Static Estimates: Dynamic Simulation of Fire-Evacuation Interaction in Historical Districts
## 4 Discussions
### Optimizing Building Environments for Historical Districts Considering Dynamic Diversity  
Although this study proposes a relatively simplified staged model, it remains important to acknowledge significant discrepancies between dynamic evacuation analyses--considering fire progression--and static analyses that neglect such dynamics, both globally and locally, including their nonlinear interactions. Dynamic simulations clearly demonstrate that fire progression continually influences the operational capacity of transportation systems. Specifically, the ignition location and wind direction not only affect disaster propagation patterns but also significantly shape the spatial distribution and intensity of traffic congestion and evacuation flows. Such inherent dynamic complexity presents substantial challenges to previous studies on historical district evacuations, which predominantly relied upon static analyses based on single-scenario assessments. Several notable differences emerge between static and dynamic approaches. Firstly, evacuation durations significantly increase under multiple dynamic scenarios. Simulation results indicate that more than 50% of evacuees experience evacuation times approximately twice as long as those predicted by static analyses--findings consistent with results reported in other studies [16; 17]. Given the typical spatial and infrastructural characteristics of historical districts, these insights are likely generalizable to other similar urban settings. Secondly, different stages of fire progression have distinct impacts on infrastructure. In particular, during the initial stages of a fire, the rate of road blockage increases substantially faster than the rate at which buildings become fully engulfed by flames. Thirdly, the spatial relationship between the ignition point and the shortest evacuation routes significantly influences evacuees' detour behaviors. Fourthly, the dynamic traffic loads on individual roads vary considerably across different scenarios. These findings underscore the limitations of previous research, which primarily utilized single-mode, static analyses and therefore could not fully capture the complex evacuation dynamics present in historical districts [20; 24; 59]. Therefore, we advocate for an approach in fire hazard analysis and evacuation planning that first evaluates a diverse set of scenarios using dynamic methods, incorporating multiple variables and conditions. An envelope approach should be employed to integrate results from multiple worst-case scenarios. For example, given uncertainties associated with specific evacuation warning distances, the most adverse scenario (e.g., a 600 m warning distance) should be applied to determine evacuation corridor widths. Additionally, entrance widths at the external emergency shelter (specifically the 70 m western entrance and 7 m southeastern entrance at Diqing Square) on both the eastern and western sides should be designed to accommodate maximum pedestrian flow observed across all potential scenarios. This study is limited by methodological constraints, as it does not include real-world validation and does not account for certain fire-related factors such as psychological panic responses on evacuation behavior. Additionally, it omits certain built environment changes and psychological behaviors during evacuation, such as the destruction of evacuation signage due to fire, which could lead to disorientation and panic. Previous studies have demonstrated that these elements can further complicate evacuation dynamics. For example: Crowd density and panic levels have been shown to affect evacuation efficiency in crowd panic dynamics models [55]; stronger herd behavior has been found to reduce evacuation efficiency in cruise ship emergencies [56]; the accuracy of emergency evacuation simulations has been analyzed based on community layout, population distribution, and key parameters [57]; the role of emergency signage in subway evacuations has been assessed for its impact on evacuation efficiency [58].