Amid the country's drive to expand the operating mileage of railways, builders from China Railway No 4 Engineering Group (CREC4) have begun laying tracks for a new high-speed railway in Southwest China.

CREC4 builders began laying the first set of 500-meter-long steel rails on May 8 in Yibin, Sichuan province, officially kicking off the commencement of the full track-laying project for the Yibin-Yanjin South section of Chongqing-Kunming HSR.

Li Zhongqiang, CREC4's technical leader of track laying for the project, said as a crucial component of China's "Eight Vertical and Eight Horizontal" HSR network, the Chongqing-Kunming HSR starts from Chongqing West Station — and after traversing Chongqing municipality, Sichuan, Guizhou, and Yunnan provinces — ends at Kunming South Station, spanning some 700 kilometers with a designed speed of 350 kilometers per hour.

Divided into three sections for construction — the Chongqing-Yibin section (Chongqing West to Yibin), the Sichuan-Yunnan section (Yibin to Yanjin South), and the Yunnan section (Yanjin South to Kunming South Station) — the Chongqing-Yibin section has been in operation since Sept 29, 2024, while the Sichuan-Yunnan and Yunnan sections are progressing in an orderly manner, Li said.

He added that the total track laying (including station lines) for the Yibin-Yanjin South section extends some 157 kilometers, with about 152.4 kilometers for the main line and 4.64 kilometers for the station lines.

"The terrain features significant undulations and is characterized by numerous long tunnels, limited working space, and multiple blind spots in communication and signaling along the route," Li's colleague, Deng Yutao, noted.

The CREC4 builders have put into place 32 fixed group cranes, 80 railway flatbed vehicles, two DF4B locomotives, one ballastless track laying unit, and two mobile flash welding machines to ensure the full success of the track-laying engineering, Deng said.