Photo taken on Nov. 20, 2018 shows the tunnel boring machine in the Qinghuayuan tunnel at a construction site in Beijing, capital of China. The work on Qinghuayuan tunnel was completed on Tuesday. The tunnel is 6.02 km in length and 12.64 meters in diameter. The completion of the tunnel laid the foundation for the opening of the Beijing-Zhangjiakou high-speed railway by the end of 2019. (Xinhua/Xing Guangli)