On 28/7, the Hanoi Metropolitan Railway Management Board (MRB) announced that TBM 1 reached Van Mieu Station (S11), marking a significant engineering milestone in the underground construction of the Nhon-Hanoi Railway metro line.

Launched from Kim Ma Station (S9) a year ago, TBM 1 has bored 2,028 meters to reach Van Mieu Station (S11), installing 1,350 tunnel lining rings. The machine is scheduled to excavate 4 kilometers of tunnel (from station S9 to station S12 - before Hanoi Station) in 16 months.

TBM 2 began operations on 3/2/2025 and has excavated 899 meters, installing 599 tunnel lining rings. Together, the two TBMs have excavated nearly 3,000 meters of tunnel.

TBM 1 arrives at Van Mieu Station on 28/7. Photo: MRB

The MRB reported that Contract Package CP03 (tunnels and underground stations) is nearly 63% complete, with construction underway across all sites. At Cat Linh Station (S10), work includes auxiliary structures on the south side, excavation for northern auxiliary structures, and construction of the main station's box walls. At Van Mieu Station (S11), the base slab concrete pouring is complete, and work continues on the southern auxiliary structures. At Hanoi Station (S12), the mezzanine and transfer floor slabs are complete, with concrete pouring underway for sections of the base slab.

Nearly 3,000 meters of tunnel have been completed by the two TBMs. Photo: Giang Huy

The two TBMs, manufactured by Herrenknecht (Germany), were custom-designed for the Nhon-Hanoi Railway metro line project. Each machine is over 100 meters long and weighs approximately 850 tons. Over 150 people are involved in the tunneling operation.

The TBMs operate in a closed-loop system, excavating at a maximum speed of 60 mm/minute. During excavation, they inject a soil conditioning agent (foam) ahead of the cutting head to soften the earth, prevent clogging, and maintain pressure balance. Simultaneously, the tail of the machine applies grease to the exterior of the tunnel lining, protecting the tail brushes, preventing water backflow, and sealing the lining segments. Grout is also injected at the tail to fill the gap between the lining and the surrounding earth, preventing subsidence during construction. After excavation, the TBM installs tunnel lining segments immediately behind the machine. Each ring, composed of six segments, takes about 30-35 minutes to install. The cycle of excavation and lining installation is continuous.

The Nhon - Hanoi Railway metro line. Graphic: An Nhien

According to the MRB, after completing the excavation at Hanoi Station (S12), the cutter heads of both TBMs will be dismantled at the station. The remaining auxiliary equipment will be pulled back and dismantled at Kim Ma Station (S9).

The 12.5-kilometer Nhon-Hanoi Railway metro line (Line 3) has eight elevated stations and four underground stations. The 8.5-kilometer elevated section runs from Nhon to Cau Giay, while the 4-kilometer underground section runs from Cau Giay to Hanoi Station. From Thu Le Station (S8), the line goes underground, passing through stations S9, S10, S11, and S12.

The project, initiated in 2009, was originally scheduled for completion in 2015 but has faced multiple delays. The elevated section began commercial operations on 8/8, and the entire line is expected to be completed in 2027.

Vo Hai