Mud gushes out from under-construction Hanoi metro tunnel, blocks street

The mud along with water and tunneling additives completely covered a seven-meter-wide sidewalk and three meters of road, or a fifth of its total width.

The contractor, who is extending the Nhon – Hanoi Station line, had to cordon off part of the street and coordinate with the police to redirect traffic.

A 15-meter stretch of Cat Linh Street in Hanoi’s Dong Da District is flooded with mud on May 27, 2025. Photo by VnExpress/Hoang Phong

The Hanoi Urban Railway Management Board later confirmed that the mud eruption was caused by a TBM that was drilling between the proposed Cat Linh and Van Mieu stations.

"As soon as it was detected, the contractor activated the project's emergency protocol, halting TBM No. 1 to reduce the amount of mud, while still ensuring tunnel face stability."

The contractor has since cleaned up the mud and re-evaluated geological conditions in the area to stabilize the situation.

Five families living above the tunneling area were notified and evacuated for two days.

To ensure safety during the tunneling process, the board had already issued relocation notices to nine households and provided temporary housing support for one month.

Two other households have handed over their properties for demolition and are receiving support for building new houses.

 

 

Mud gushes out from under-construction Hanoi metro tunnel, blocks street

Bùn trào ra phố do khoan ngầm dự án metro Nhổn - ga Hà Nội

Once in February too mud gushed out during boring and filled an alley on Giang Van Street in Ba Dinh District.

The board later quoted TBM lead engineer Salvatore La Valle as saying "old wells and drainage pipes under the ground had created pathways for the mud and tunneling additives to rise to the surface."

The tunneling additives used are non-toxic and environment-friendly, meet European standards and have passed rigorous board inspection.

The board assured that the incident did not affect the structural integrity of the tunnel or cause any casualties. TBM No. 1 has so far bored 1.2 km of tunnel and continues at an average rate of 10–12 meters per day.

The Nhon – Hanoi Station line will run 12.5 km and have 12 stations, four of them underground. The 8.5 km surface section has been in commercial use since August 2024.

The underground section is expected to be completed by 2027.