In this aerial photo taken on April 2, 2019, a Line S2 train of Beijing Suburban Railway (BSR) pulls out of Qinglongqiao station of the Beijing-Zhangjiakou railway in Beijing, capital of China. (Xinhua/Ju Huanzong)
In this aerial photo taken on April 2, 2019, a Line S2 train of Beijing Suburban Railway (BSR) stops at Qinglongqiao station of the Beijing-Zhangjiakou railway in Beijing, capital of China. (Xinhua/Ju Huanzong)
Photo taken on Oct. 18, 2018 shows Qinglongqiao Station of the Beijing-Zhangjiakou railway in Yanqing District, Beijing, capital of China. (Xinhua/Zhang Chenlin)
Staff members work at the construction site of the Xiahuayuan section of the Beijing-Zhangjiakou railway in north China's Hebei Province, May 7, 2019. (Xinhua/Xing Guangli)
Photo taken on May 6, 2019 shows Qinghe Station of the Beijing-Zhangjiakou railway in Haidian District, Beijing, capital of China. (Xinhua/Xing Guangli)
This undated file photo shows trains running on the zigzag upward railways of Beijing-Zhangjiakou railway that overcomed the gradient problem by switching back the line near the station of Qinglongqiao in Yanqing District, Beijing, capital of China. (Xinhua)
File photo taken in 1909 shows Zhan Tianyou (3rd R, Front) poses for a group photo with his colleagues for the completion of the Beijing-Zhangjiakou Railway. Zhan presided over the construction of the railway line, the first one designed and built by Chinese. (Xinhua)
Photo taken on Oct. 18, 2018 shows the bronze statue of Zhan Tianyou at Qinglongqiao Station of the Beijing-Zhangjiakou railway in Yanqing District, Beijing, capital of China. (Xinhua/Zhang Chenlin)
A staff member gestures as the last train runs out of the Zhangjiakou North Railway Station before it was discharged in Zhangjiakou, north China's Hebei Province on June 30, 2014. (Xinhua/Yang Shiyao)
A train runs on the Juyongguan Pass section of the Beijing-Zhangjiakou railway in Beijing, capital of China, Oct. 25, 2015. (Xinhua/Yang Guang)
A train runs on the Juyongguan Pass section of the Beijing-Zhangjiakou railway, which is decorated by blooming flowers, in Beijing, capital of China, March 25, 2016. (Xinhua/Wang Xibao)
A train runs on the Juyongguan Pass section of the Beijing-Zhangjiakou railway, which is decorated by blooming flowers, in Beijing, capital of China, March 25, 2016. (Xinhua/Wang Xibao)
Photo taken on Nov. 9, 2016 shows the construction site of a bridge of the Beijing-Zhangjiakou railway on Guanting reservoir, north China's Hebei Province. (Xinhua/Yang Shiyao)
Workers are seen at the construction site of the Great Wall station of the Beijing-Zhangjiakou railway under the Badaling Great Wall area in Beijing, capital of China, Aug. 8, 2017. (Xinhua/Li Wen)
Photo taken on Oct. 18, 2018 shows Qinglongqiao Station of the Beijing-Zhangjiakou railway in Yanqing District, Beijing, capital of China. (Xinhua/Zhang Chenlin)
