Zhaotong Tunnel fully breakthrough completes all tunnelling works on Chongqing–Kunming high-speed railway

According to People’s Network Yunnan Channel reports, Zhaotong Tunnel, a key control project along the Chongqing–Kunming high-speed rail line, achieved full breakthrough on 26 June. The milestone marks the completion of all tunnel construction works across the entire route.

The tunnel sits within the hinterland of the Wumeng Mountains in Yiliang County, Zhaotong City, Yunnan Province. It stretches 16.26 kilometres in total, with a maximum overburden depth reaching 980 metres. 

The alignment cuts through 18 distinct complex stratigraphic sequences and two regional fault zones, bringing together a full spectrum of severe geological hazards including coal and gas outbursts, large deformation of deep-buried soft rock, intense tectonic disturbance along fault planes, extensive karst development, plus high-pressure karst groundwater inflows. It is designated as a Class I high-risk tunnel under national railway engineering standards. Teams on site have rolled out innovative construction techniques and dynamically revised excavation schemes to resolve a string of harsh engineering obstacles encountered throughout the build phase.

The Chongqing–Kunming high-speed railway forms a vital segment of the Beijing–Kunming passage within the national eight vertical and eight horizontal high-speed rail network. Running for approximately 700 kilometres end to end, it stands as the first high-speed rail route in Yunnan Province engineered for a design operating speed of 350 kilometres per hour. 

Once the full line opens to passenger services, travel durations between major regional hubs will see substantial cuts. Journeys between Kunming and Chongqing will shrink to roughly two and a half hours, while trips from Kunming to Chengdu will take under three hours. Improved transport connectivity will unlock fresh momentum for high-quality economic and social development across all towns and counties along the rail corridor.

Industry specialists note that the line carries an extremely high bridge-tunnel ratio, a common feature of mountainous high-speed rail projects in southwest China. The successful breakthrough of Zhaotong Tunnel removes the most formidable geological bottleneck holding back the overall progress of the scheme. 

All tunnelling sections now stand finished, clearing the way for subsequent track laying, electrification and signalling installation phases to advance in a continuous sequence. Completion of the full infrastructure package will deliver faster, more reliable passenger transport links that strengthen cross-regional circulation of personnel, goods and resources across southwest China’s major urban clusters.