In June 2021, the monthly advance of the main tunnel construction assisted by the shaft on the right line of the Changning Tunnel reached 102.8 m, achieving the goal of breaking the 100-meter mark in a single month. As of July 1, cumulative construction of the Changning-end of the main tunnel assisted by the shaft on the right line reached 324.8 m, and construction of the Baoshan-end assisted by the right line reached 286 m, for a cumulative total advance of 610.8 m.

The Changning Tunnel shaft is located 5 m to the left of the right tunnel bore at YK30+518, about 2.5 km from the Changning end of the tunnel and about 2.9 km from the tunnel exit end. The shaft cross-section adopts a circular section with high ventilation efficiency and favorable structural stress, with an inner diameter of 9.2 m and a depth of 253 m. It is the most important auxiliary gallery of the Changning Tunnel, shouldering the important tasks of increasing working faces to achieve "long tunnel, short driving" and later tunnel operation ventilation.

Facing complex and changeable geological conditions, the Changbao team carried forward the "Guangxi Road and Bridge Group" spirit of the road-and-bridge iron army—especially able to endure hardship, especially able to fight, and especially able to make sacrifices—and took multiple measures to rise to the challenge:

Actively carried out relevant scientific research topics and technical tackling work, built a technological innovation system with deep integration of production, learning, and research, and supported on-site construction.

Construction adhered to the principles of "advanced pipe forepoling, strict grouting, weak blasting, short advance, strong support, frequent measurement, and early closure" to ensure steady project progress.

Strengthened safety technical disclosure and education and training to ensure that safety education extends horizontally to the edges and vertically to the bottom, leaving no blind spots; always adhered to the "life first" safety production principle, organized and formulated safety management measures according to the actual situation of shaft-assisted construction, and refined a series of safety production systems such as safety production responsibilities; improved underground emergency escape plans and organized emergency rescue escape drills every month to escort the construction of the main tunnel assisted by the shaft on the right line.

Strengthened quality management and established and improved the quality assurance system.

The new construction mode of "long tunnel, short driving" opened a new door for Changning Tunnel construction! As of July 1, the cumulative advance of the left bore of the Changning Tunnel was 2,776.2 m, with a cumulative completion ratio of 50.9%, and the cumulative advance of the right bore was 3,307.6 m, with a cumulative completion ratio of 60.9%. Next, all participating construction personnel will, with firm confidence and a decisive attitude, hold firmly to the goal, overcome difficulties, complete the target tasks with guaranteed quality and quantity, and resolutely win the "hard battle" of Changning Tunnel construction.