Thu Thiem tunnel sections ready for immersion under river

Sections of the Thu Thiem tunnel to be installed underwater in Ho Chi Minh City’s Saigon River are now ready for transfer and immersion, according to project officials.

The unique process, to be carried out for the first time in Vietnam, will see four tunnel sections measuring each 90 meters in length, 33 meters in width, and 9 meters high, submerged under the river.

Workers and engineers prepare equipment for the immersion of Thu Thiem tunnel sections in the Saigon River, District 1, HCMC. (Photo:SGGP)

Workers and engineers at both the fabrication yard in Dong Nai Province’s Nhon Trach District and the tunnel construction site in District 1, HCMC, have been working overtime to ready equipment for the installation process.

The project contractor will use four tugboats to pull the tunnel sections, weighing 27,000 tons each, from Dong Nai Province to the tunnel construction site in HCMC’s District 1.

Transfer of the sections is scheduled for March 7 with the travel time expected to take around 10 hours.

Plans call for the underwater placement of the first section to be carried out on March 9.

According to director of the project management board Luong Minh Phuc, after each tunnel section is transferred to its immersion site, engineers will take over to place the sections in their correct position.

A group of around 20 engineers and divers will work at the riverbed while water is pumped into the sections to help position them. When the sections are in place, construction teams will then pump water back out of the tunnel.

Immersing the sections is expected to take 36 hours each.

The Saigon River will be closed to waterway traffic from Binh Khanh Confluence to My Canh Wharf for two days next week due to work on the project.

The HCM City Maritime Agency said vessels of all types would be prohibited from traversing the section between 7am and noon on Sunday when the tunnel's first concrete module is towed in from Dong Nai Province.

The stretch between My Canh and Nha Rong wharves will be closed from noon on Sunday to midnight on Monday when the module is installed.

It is expected that all four sections will be submerged over the next three months and then connected to the rest of the tunnel in late August.

Once completed, the immersed tunnel will measure about 370 meters in length with six lanes – three for each direction for automobiles and motorbikes. The tunnel also includes two emergency lanes and has a speed limit of 60km/hour.

Safety concerns are being addressed with the installation of technical systems inside the tunnel for ventilation, water pumping, damp-proofing, lighting, telecommunications, emergency-alert systems, fire and explosion prevention systems; and automated gauges to measure noise, moisture, dust and exhaust.

There are around 105 such tunnels worldwide, 30 of which are immersed under water, mostly in Japan, Hong Kong (China), Shanghai, Australia, the US, and the UK. In Southeast Asia, Vietnam is the first country to install such a tunnel.

By Quoc Hung, translated by Ky Linh

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