On August 16, the left line of the shield tunnel section from Lieshi Park East Station to Simaochong Station of Changsha Metro Line 3 Phase I successfully crossed under the Beijing-Guangzhou Railway frame bridge. So far, both the left and right lines of this shield section have successfully completed the crossing of the Beijing-Guangzhou Railway. As of yesterday, the speed-restricted section of the Beijing-Guangzhou Railway (from Simaochong to Changsha East Station) has officially resumed normal-speed operation. This marks that Changsha Metro Line 3 has successfully overcome another major difficulty in construction control of the project. The Beijing-Guangzhou Railway is an important national railway trunk line, and the frame bridge under which the dual lines of the Lieshi-Simaochong section of Changsha Metro Line 3 pass is 35m long; the underpass section is a ballasted track shared by passenger and freight trains. On the frame bridge are the up and down lines of the Beijing-Guangzhou Railway, as well as 3 tracks diverging from the down line; trains must pass through this turnout to enter Changsha Railway Station or Changsha Freight Station. This section is an important node of the Changsha section of the Beijing-Guangzhou Line. To ensure the operational safety of Beijing-Guangzhou Railway trains and the smooth progress of construction during the metro underpass, the speed of passing trains needed to be reduced from 135 km/h to within 45 km/h, and the settlement of the Beijing-Guangzhou frame bridge and its track surface needed to be controlled within 5mm. Changsha Rail Transit organized the relevant participating units to plan ahead, make early arrangements, and implement quickly. They actively applied for a slow-speed operation plan for the Beijing-Guangzhou Railway and carried out construction in two phases. That is, during the periods from May 28 to June 3 and from August 10 to 19, a total of 17 days of speed restriction and slow operation were implemented. At the same time, construction plans such as the "Special Construction Plan for the Reinforcement Project of the Underpass of the Beijing-Guangzhou Railway" and the "Railway Operation Plan" were compiled, and detailed safety protection measures were formulated. Under slow-speed conditions, construction was coordinated, and through measures such as uninterrupted monitoring and secondary grouting, the settlement of the frame bridge and track was strictly controlled, and construction quality was rigorously supervised, ensuring the safety of personnel and railway operations during construction, and achieving the safety and quality goal of "not injuring a single person, not delaying a single point." Up to now, in addition to crossing under the Beijing-Guangzhou Railway frame bridge, the shield tunnel in the Lieshi-Simaochong section of Line 3 has also successfully passed alongside the Hunan Communications Construction Co., Ltd. building and crossed under four high-risk sections including the silty clay layer and the Changsha Sanjiaotang Pump Station. Moreover, the tunnel in this section is located directly beneath the main road of Chezhan North Road, where people and vehicles are dense. Because it is near the Liuyang River, the stratum is rich in water, the geological conditions are complex and variable, and construction is difficult. In the next stage, this section will carry out long-distance underpass construction beneath the drainage main canal.