## 5 Conclusions  
The accident rescue of railway dangerous goods accident has the characteristic of time urgency, the accident itself has continuous expansion, the traffic environment has uncertainty and the accident rescue needs multiple rescue resources. Therefore, it is necessary to integrate and reasonably arrange appropriate rescue resource scheduling and routing plans. According to the analysis of travel time and reliability for rescue routes, considering the factors such as rescue capacity, rescue demand and response time, a multi-objective scheduling model of rescue resources based on travel time reliability is constructed in order to minimize the total arrival time of rescue resources and to maximize total reliability. Considering travel time and reliability of the rescue route, the proposed model is more reliable than the traditional model.  
Furthermore, a two-stage algorithm is designed to solve this problem. In the first stage, a multi-path algorithm with a bound constraint is used to obtain the set of feasible routes from each rescue center relative to the accident location. In the second stage, the NSGA-II algorithm is used to determine the scheduling of rescue resources for each rescue center. Finally, a regional road network is collected to test multi-objective scheduling and algorithm. The results show that the designed two-stage algorithm can simplify problem solving and effectively improve solving speed, and it is valid for solving the rescue resource scheduling problem of dangerous goods accidents.  
In order to reduce emergency response time when an accident occurs, the location in relation to transport and storage of dangerous goods should formulate an emergency plan. At the same time, emergency personnel should be trained to improve their emergency safety technical knowledge and master certain abilities in order to prevent and deal with accidents. Emergency drills should be organized regularly to improve risk awareness in dealing with emergencies and abilities related to emergency response. Furthermore, each rescue unit should reserve sufficient materials required for railway dangerous goods accidents within the emergency scope and plan the rescue route in advance.  
In this paper, we assumed that the demand for the rescue resources is known. In reality, the running time may be uncertain due to the complexity of dangerous goods accidents. Moreover, travel times are time-varying and stochastic in transportation because of the effects of traffic flow and weather. Therefore, future research can consider the following:  
1. Considering the uncertainty of the demand for rescue resources to design a model and algorithm of rescue resource scheduling problem;
2. Considering the travel time of links in stochastic, time-varying transportation networks to research the rescue resource scheduling problem;  
Figure 9: The rescue resource scheduling of Scheme 2.  
Considering the priority of rescue equipment and resources to research on the rescue resource scheduling problem.  
The contributions of the authors were distributed in the following manner: Conceptualization, L.L.; methodology, X.Y. and L.L.; software, X.Y.; validation, L.L.; formal analysis, X.Y.; investigation, L.L.; data curation, X.Y.; writing--original draft preparation, X.Y.; writing--review and editing, L.L.; supervision, X.Y.; project administration, X.Y.; funding acquisition, X.Y. and L.L. All authors have read and agreed to the published version of the manuscript.  
This work is supported by the National Natural Science Foundation of China (Grant No. 71761024), the Natural Science Foundation of Gansu Province of China (No. 21 JR1 RA236) and Double-First Class Major Research Programs, Educational Department of Gansu Province (No. GSSYLXM-04).  
Not applicable.  
Data Availability Statement: Data sharing is not applicable to this article.  
The authors declare no conflict of interest.