The site inspection was conducted as part of the project’s third-quarter 2026 coordination meeting. In the photo: Delegation inspects construction at VH3A access tunnel.

Since mid-March 2026, the VH3A tunnel has encountered a Grade IV geological fault zone. This is a highly complex geological condition in which the rock mass is heavily fractured, deformed, crushed or transformed into characteristic rock types under intense friction and pressure generated by movements of the Earth’s crust. In the photo: Inspection of construction inside VH3A tunnel.

A drilling machine is used to install support frames and apply shotcrete to reinforce the tunnel crown during construction of the section of the VH3A tunnel passing through the geological fault zone.

Steel support frames are used to reinforce and stabilize the tunnel crown during construction of the VH3A tunnel. The frames are custom-fabricated to match the dimensions and shape of the tunnel cross-section.

One of the major construction challenges in recent months has been heavy rainfall occurring almost daily, significantly affecting the access road serving construction activities. The crushed-stone base layer laid by the contractor has been repeatedly washed away by the heavy rain, leaving many sections muddy and potholed and causing difficulties for the transport of materials and equipment as well as personnel movement.

The access road to the construction site passes by Song Cai Reservoir, which will directly supply water for the closed-loop operating cycle of the Bac Ai Pumped-Storage Hydropower Plant once it enters operation.

Following the site inspection, the EVN delegation continued with the project’s third-quarter 2026 site coordination meeting at the Project Executive Board’s office. EVN’s website, evn.com.vn, will continue to provide updates on the working program.