Chongqing - On July 5, the Chongqing-Yibin section of the Chongqing-Kunming High-Speed Railway  (HSR) achieved a test speed of 385 km/h, marking a significant phase in the joint commissioning process after a series of step-by-step speed increase tests.

The 699-kilometer Chongqing-Kunming HSR, designed for 350 km/h, is a key segment of the Beijing-Kunming corridor in China's "eight vertical and eight horizontal" railway network. The Sichuan-Chongqing section is set to open by the end of 2024.

The train is running on the Chongqing-Yibin section of the Chongqing-Kunming High-Speed Railway. (Photo/China Railway Chengdu Bureau Group Co., Ltd.)

The Chongqing-Kunming HSR begins at Chongqing West Railway Station and travels through Shapingba, Jiulongpo, Dadukou, Jiangjin, Bishan, and Yongchuan districts and the High-Tech Development Zone in Chongqing. It then links Luzhou and Yibin in Sichuan and Bijie in Guizhou before passing through Zhaotong and Qujing in Yunnan, ending at Kunming South Railway Station.

The train driver is operating the test train. (Photo/China Railway Chengdu Bureau Group Co., Ltd.)

The step-by-step speed test gradually increased the train's speed to 110% of the design speed, starting from 180 km/h and peaking at 385 km/h over 16 levels, confirming the railway's ability to meet its design speed targets.

Once fully operational, travel time between Chongqing and Kunming is expected to be reduced from 5 hours to approximately 2 hours, enhancing the national comprehensive transportation network and strengthening ties between the Chengdu-Chongqing economic circle and Yunnan's central area.

Additionally, it will strongly support regional integration and connectivity within the Yangtze River Economic Belt, significantly boosting the coordinated and sustainable development of regional economic and social initiatives.

Since the project's inception in 2020, construction teams have overcome challenging geological conditions, high temperatures, power restrictions, and other difficulties to ensure progress, quality, and safety.

The Tuojiang Super Bridge, the most challenging to construct on the Chongqing-Kunming section, is located in Luzhou's suburbs. It spans 2613 meters and has a main bridge tower 115.7 meters high, equivalent to a 40-story building. It features a unique double-column V-shaped tower on its two main piers, the first of its kind in China.

The Tuojiang Super Bridge. (Photo/China Railway Chengdu Bureau Group Co., Ltd.)

"The concrete volume covering some 2,000 square meters and up to 13 meters tall is immense. It required extremely high-stress performance and installation accuracy in the overall load-bearing brackets," said Yin Ze, chief engineer of the project from China Railway No.4 Engineering Group Co., Ltd (CREC4).

Yin explained that the steel bars on the two blocks, weighing over 150 metric tons, are highly complex due to the 23,000 bars in 69 different forms, creating significant construction risks in the limited working space.

Yin said that the joint research team set up a task force to make technological breakthroughs, laying a solid technical foundation for the successful pouring.