After more than 2,000 construction workers carried out six hours of intensive "window" work, the Fengsha Railway, which underwent reconstruction for two years and three months, opened smoothly to traffic. The reporter learned at the construction site that the 62-year-old Fengsha Railway was rebuilt to coordinate with the Chang'an Avenue westward extension project and the overall planning of the Shougang area. It is also the first existing railway line in the city to be moved from above ground to underground to coordinate with urban road planning. Some industry experts said that for intercity railway lines under construction, including Beijing-Tangshan and Beijing-Xiong'an, as well as new railway lines planned for the longer term, urban sections gradually moving "underground" to free up space for urban road planning is a trend.

　　Reconstruction: Moving underground for the Chang'an Avenue westward extension

　　At 9 a.m., the reporter rushed to the Fengsha Railway construction command center near Gucheng in Shijingshan District, where dozens of workers were working between the newly built track lines. According to Shen Yenan, chief engineer of the Fengsha Line reconstruction project of China Railway Sixth Group Beijing Railway Construction Company, because the extended Chang'an Avenue will pass through the Yongding River and the Fengsha Railway in Shijingshan District and reach Mentougou on the outskirts of Beijing, the Fengsha Line launched its reconstruction project in 2015 to move from above ground to underground and avoid an intersection between the railway and the Chang'an Avenue westward extension road.

　　The reporter learned at the site that the reconstruction project is located between Lianshi Road and Fucheng Road outside the West Fifth Ring Road in Beijing, runs parallel to the existing Fengsha Railway, and passes underground in tunnel form beneath the west side of the Shougang plant area, Shijingshan, and the south side of the Jingneng Thermal Power Plant plant area. The reconstructed line is 6.99 kilometers long in total, with 4.35 kilometers of underground tunnel.

　　Blasting beneath the dense cultural relic area of Shijingshan. "Because the Fengsha Railway reconstruction project is located in Beijing's urban area, close to the existing Fengsha Railway, and surrounded by densely distributed factory buildings and cultural relics, above the tunnel are the Gongbei Pavilion and the Tianzhu Palace courtyard, key cultural relics of Shijingshan District, and the nearest distance to the Shougang civil air defense passage is only about 2 meters. Affected by this, the Fengsha Line reconstruction project is extremely difficult to construct."

　　Shen Yenan said that the Fengsha Railway reconstruction project faced great difficulties in internal and external coordination, safety management, and construction organization. In particular, the use of micro-vibration blasting construction technology to pass beneath the Shijingshan mined tunnel placed higher demands on construction organization and safety control, requiring the blasting vibration velocity not to exceed 5 centimeters per second. "In the end, we completed the blasting smoothly in nine months," Shen Yenan said.

　　Hard work: 2,000 construction workers work for six hours

　　The reporter learned that because the existing operational main Fengsha Line runs right beside the reconstructed line, in order to minimize the impact of construction on passenger travel, starting at 4:30 yesterday, 2,000 workers began simultaneously carrying out first-level track diversion work during a railway possession window. Simply put, within the requested working time and during the gap when no trains were passing, the construction workers had to cut the tracks of the original Fengsha Railway line, weld them to the newly laid tracks, and complete signal testing and other work.

　　"We chose this morning time slot for construction because fewer trains pass during this period. After we applied for the 'working time,' fewer trains were affected," Shen Yenan said.

　　At 10:20 a.m., all work was basically completed. At 10:40 a.m., two freight trains, one from Shijingshan South Station to Anjiazhuang Station and the other from Sanjiadian Station to Fengtai West Station, roared past and were the first to enter the newly opened section of the Fengsha Line.

　　Outlook: Railways "going underground" will become a trend

　　The reporter learned that the smooth opening of the Fengsha Railway reconstruction project has enhanced the overall image of the Shougang area and the Yongding River area, and is of positive significance for driving the development of Mentougou and Shijingshan Districts and relieving some functions of the central urban area.

　　The Fengsha Railway is a railway line connecting Fengtai District in Beijing and Shacheng Town in Huailai County, Hebei Province. It is 106 kilometers long, was built from 1952 to 1955, and opened to traffic in 1955. It is the second corridor from Beijing to the important northwestern Hebei towns of Shacheng and Zhangjiakou after the Beijing-Baotou Railway, and is also one of the main corridors for transporting Shanxi coal outward.

　　Regarding the Fengsha Line moving from above ground to underground this time to make way for the Chang'an Avenue westward extension project, industry experts said this is the first time an existing railway line in Beijing has given way to urban planning. At present, railway lines under construction, including Beijing-Tangshan, Beijing-Binzhou, and Beijing-Xiong'an, all have underground sections. Freeing up space for urban road planning and avoiding intersections, with railways gradually moving "underground," is a trend in future railway planning and design. The smooth reconstruction of the Fengsha Line this time also provides valuable experience for future railway planning and construction.