# Modeling of a Coal Transshipment Complex Based on a Queuing Network
## 6 Conclusions  
Currently, the Asia-Pacific region is witnessing the construction of new coal-fired thermal power plants in response to the rising need for electricity. Such a situation will require an increase in the volume of coal transportation, particularly by sea, and, consequently, the establishment of new terminals and the upgrade of existing marine ones. Therefore, the development of tools that allow analyzing the port infrastructure and related land transport systems as a single complex is significant.  
The results obtained in this study contribute to the solution to the described problem. We have presented a model algorithmic toolkit for studying the operation of a marine transshipment complex, which includes a coal terminal and an associated railway station.  
Our approach is based on queuing networks with batch incoming flows and several types of requests. As a result, the model considers the influence of random factors on the running and maintaining of trains and vessels, the different number of cars in trains, vessel capacity, the hierarchical structure of the system, and the operating features of its elements.  
The simulation of the resulting QN allows one to determine the bottlenecks and pre-evaluate the effectiveness of various measures to eliminate them. Moreover, the proposed model is highly adaptive and can be applied to terminals with different structures in a relatively short time. Another advantage of the presented tools is that high-performance equipment is not required to conduct computational experiments and personal computers can be used.  
Using the presented model, we simulate the joint operation of the Toki railway station and the Daltransugol JSC export coal terminal, one of the largest and most modern terminals in Russia. The operation of the system is studied during the summer period, which is the most critical, since the volume of incoming trains with coal is maximum. Based on the results of numerical experiments, we have estimated the current and maximum throughput of the transshipment complex and forecast its capacity after the planned modernization.  
Further research can concentrate on the following points. The first is to develop the proposed approach by applying a non-stationary process for servicing requests, which allows for the consideration of breaks for personnel and equipment shutdown for maintenance. The second is to apply the presented tools to describe other types of marine terminals, in particular container and oil terminals. The operation of the system in winter is also worth studying, since the volume of train traffic decreases but additional time is required to crush frozen coal from incoming trains.  
Conceptualization, A.K. and M.Z.; methodology, A.L. and M.Z.; software, M.Z.; validation, A.K. and A.L.; formal analysis, M.Z.; investigation, A.K. and M.Z.; resources, M.Z.; data curation, A.K. and M.Z.; writing--original draft preparation, M.Z.; writing--review and editing, A.K. and A.L.; visualization, M.Z.; supervision, A.K.; funding, A.L. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Russian Science Foundation (project No. 24-21-00264).  
Not applicable.  
Data Availability StatementData are not publicly available, though the data may be made available on request from the corresponding author.  
The authors declare no conflicts of interest.