## 4 Discussion and Outlook
For the start-up time control of the transport units, a similar analysis process to the Dynamic Fault Tree analysis method has been established to control each transport unit to the Stope to participate in transport operations by the ATS system. For the route adjustment of the transport units, a process based on the shortest-path algorithm [43; 44; 45; 46; 47] has been established to adjust the running route of each transport unit to improve the transport efficiency and reduce the cost of the distance and the time. Finally, for the transport units tracking, the tracking equations based on the digraph have been established to solve the problem in which the position information of each transport unit is inaccurate and discontinuous in underground transportation. The concept paper tries to summarize and propose the solutions to the practical problems in the engineering of transportation in underground mines with the assistance of the CBTC system; the functions of the CBTC system and its subsystems are also improved and applied to the solution of problems in the transportation of the underground mines. However, in the future, the CBTC system might be replaced by more advanced systems. In 2016, [PERSON] [37] raised his prospect of the NGTC (Next Generation Train Control) project; he thought that most of the functions of the CBTC system have gradually fallen behind. In 2021, as the representative of developing countries, China's research on the NGTC (Next Generation Train Control) system is progressing rapidly, and there is even the possibility of pilot applications soon. Recently, Chinese researchers [PERSON] and [PERSON] [65] reported their research on the modeling and verification of the train departure scenario for the Next Generation Train Control system. With the appearance of more and more advanced systems, the dominant position of the CBTC system in urban rail transit is likely to be gradually replaced. If the CBTC system were to be replaced in the urban rail transit control system one day, there is no doubt that the CBTC system would disappear from underground mine transportation. For underground mine transportation, in 2015, [PERSON] et al. [39] published their research on the development of an underground mine monitoring and communication system that integrated ZigBee (based on IEEE802.15.4) and GIS (Geographic Information System), and they inferred that ZigBee technology and GIS would be widely used in the control and communications of the underground mine transportation in the future. For the trackless transportation of underground mines, the CBTC system may also take the leading role. Ifthe path of the trackless transport equipment is planned within a certain range, the CBTC system can still have good performance in the control and monitoring. [PERSON] [39] believes that if the low power and efficient information transmission of the ZigBee technology are applied to the underground control system, the mining industry will certainly make rapid progress; therefore, the combination of the CBTC system and ZigBee technology may be a good performance in the control and monitoring in the underground mines. As for the tracking of the underground transportation, tracking technology has made great progress in recent years. Similar to [PERSON] et al. [66], he established the tracking equations through Global Navigation Satellite System (GNSS) and Geodetic Networks in 2020. [PERSON] et al. [67] established the tracking equations by 5G technology. As science and technology progress, the method of establishing tracking equations will be improved with time, such as using 5G technology in the establishment of tracking equations. [PERSON], [PERSON], and [PERSON] [68] present an approach to model dynamic changes in ambient intelligence scenarios using the AVISPA (automated validation of Internet security protocols and applications) model-checking tool suite in 2009. According to some reports and surveys [69], the application of this technology in all walks of life in the future will be as good as people think.