# A Method for Evaluating the Spatial Layout of Fire Stations in Chemical Industrial Parks
## 3 Results and Discussion
When a PTBR falls within the yellow area (including the red area within it), it means that the estimated rescue time to reach both fire stations is less than 5 min. For a PTBR with a medium risk level, being within this area means that it is covered by both fire stations. If a PTBR falls within the red area, it indicates that the estimated rescue time to reach both fire stations is less than 3 min. A PTBR with a high-risk level is considered to be covered by both fire stations only when it falls within the red area. Figure 5 shows all the PTBRs effectively covered by the fire stations. Based on the analysis method mentioned above, it can be observed that out of the 50 effectively covered PTBRs, 31 PTBRs are simultaneously covered by Station A and Station B. The diagonal shadow area in Figure 6 represents all the cross-covered PTBRs and the corresponding regions they represent. Using Equation (4), the overlap-coverage rate of fire stations in Park X is calculated to be 62%. This exceeds the evaluation standard of 30% mentioned earlier in this article, indicating that the overlap-coverage rate of fire stations in Park X does not meet the requirement. Figure 5: Analysis diagram for the overlap-coverage rate of fire stations. Figure 2.0 The overlap-covered area by the fire stations in Park X. Although this article estimates that the speed of fire engines in Park X is 50 km/h, it is important to note that the road and traffic conditions in different chemical industrial parks may vary. Apart from the previously mentioned PTBR fire risk levels and road irregularities, the speed at which fire engines travel within the chemical industrial park is a significant factor that can impact the rationality of the fire station layout. By using Park X as an example, we conducted an analysis comparing the fire station coverage rate and the overlap-coverage rate with the estimated speed of fire engines, as illustrated in Figure 2.1 It can be observed that under specific fire risk and road conditions, the coverage rate of fire stations gradually increases as the speed of fire engines increases, while the overlap-coverage rate also experiences an increase. Therefore, accurately estimating the speed of fire engines within the concerned chemical industrial park is crucial for the layout evaluation of fire stations. Finally, a comparison between the method presented in this article and the \"Circle-drawing method\" is conducted. Taking Station B as an example, the 5 min coverage area is calculated using the method described in this article, based on the speeds of fire engines at 50 km/h and 30 km/h, respectively. The results are illustrated by the diagonal shadow area in Figure 2.2 The \"Circle-drawing method\" is utilized to draw a circle with a coverage area of 15 km\({}^{2}\) centered on Station B. It can be observed that the \"Circle-drawing method\" produces a coverage area similar to that obtained by the method presented in this article using a driving speed of 30 km/h for fire engines. However, our site survey indicates that a speed of 30 km/h seriously underestimates the actual driving conditions of fire engines in Park X. Through the comparison, it is evident that, for Park X, the coverage range of fire stations estimated by the \"Circle-drawing method\" is significantly smaller than the coverage range estimated by the method described in this article. The \"Circle-drawing method\" primarily focuses on the linear distance traveled by the fire engines. Other important factors, such as fire risk level, road paths, and fire engine speed as discussed in this article, are not included. This significantly underestimates the coverage and rescue capabilities of fire stations, which may also result in excessive economic investment. The study conducted by [PERSON] et al. yielded similar findings. They discovered that the service area boundary of the fire station was not a circle, but instead an irregular polygon, which highlights the limitations of employing the conventional circle-drawing method [47].