## 6 Conclusions and Future Work  
Based on analysis of the results of semi-structured interviews, this study proposes a system framework that facilitates the digital monitoring of asphalt concrete pavement construction based on IoT, the BeiDou navigation system, and 5G technology. In this framework, a data management system and an asphalt mixture production, mixing, transportation, paving, and rolling monitoring system are defined to realize asphalt concrete pavement monitoring from six aspects. It is proposed that based on implementing the concept of information transmission across the whole life cycle, the key data in the production process of the production, mixing, transportation, paving, and rolling of the mixture system can be acquired, and real-time linkage between the data of each system carried out. Corresponding functions of each system were also developed, such as the query of total production batches, the query of total transportation batches, and the proportion of alarms issued to operators. Users can directly operate and view the corresponding data results through real-time interaction with the system and corresponding functions.  
The study has demonstrated the system framework of a digital monitoring system for asphalt concrete pavement construction. The research team collaborated with a software company to develop an intelligent monitoring platform for asphalt pavement construction and successfully applied the platform to a digital highway construction project to validate the system framework. The results of the case study investigation highlight that the monitoring platform developed by the system framework enables monitoring of asphalt pavement construction. This led to an improved level of pavement construction and management, which is consistent with the development of the construction sector in China. The results of this empirical study support the design and development of a highway construction quality monitoring system. This system approach renders it easier and more efficient for engineering construction workers to handle, predict, and solve road construction problems, so that construction projects can be completed more efficiently.  
It is suggested that future research includes the following directions: (1) The function of the system may potentially be enhanced through reducing the level of manual operations. For example, if the temperature of the equipment is too high, automatic operation of the system can be enabled to cool the equipment without requiring workers to operate the platform. (2) There is a need to monitor the performance of the system and suitable research studies should therefore be undertaken in this area.  
Methodology--[PERSON]. ([PERSON]); writing--original draft--[PERSON]. ([PERSON]); validation--H.L.; formal analysis--[PERSON]. ([PERSON]) and Y.K.; writing--review and editing--S.P.P.; funding acquisition--[PERSON]. ([PERSON]), Y.F. and Q.N. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Branch of China Road and Bridge Corporation (Cambodia) Technology Development Project (No. 2020-2 kly-04), National Social Science Fund projects (No. 20 BY010), National Social Science Fund Post-Financing Projects (No. 19 FJYB017), Sichuan-Tibet Railway Major Fundamental Science Problems Special Fund (No. 71942006), List of Key Science and Technology Projects in China's Transportation Industry in 2018-International Science and Technology Cooperation Project (No. 2018-GH-006 and No. 2019-MS5-100), Emerging Engineering Education Research and Practice Project of Ministry of Education of China (No. E-GKRWJC20202914), Shaanxi Social Science Fund (No. 20175004), and Xi'an Construction Science and Technology Planning Project (Nos. SZJJ201915 and SZJJ201916).  
The authors declare no competing financial or non-financial interest.