Landslides near underground tunnels poses risk for North-South train line

May 31, 2024 - 08:03
The North-South railway, spanning from Quảng Bình province to Khánh Hòa province, includes 27 tunnels constructed nearly a century ago (between 1926 and 1936) under the standards and technology of that time. These tunnels, lined with concrete or stone, have deteriorated significantly, exhibiting cracks and water leaks that pose safety risks to train operations.
Repairs underway in the Chí Thạnh tunnel after the landslide on May 22. VNA/VNS Photo Tường Quân

HÀ NỘI In less than a month, the vital Hà Nội-Hồ Chí Minh City railway line (North-South railway) experienced two landslides at the Bãi Gió Tunnel (Khánh Hòa Province) and Chí Thạnh (Phú Yên Province), which cost tens of billions of đồng in repairs, as well as causing interruptions for thousands of passengers.

Though these particular incidents were dealt with swiftly and travel restored, the solutions may only be temporary and the risk of further landslides along the North-South railway remains a possibility.

Unprecedented high level of risk

The North-South railway, spanning from Quảng Bình Province to Khánh Hòa Province, includes 27 tunnels constructed nearly a century ago (between 1926 and 1936) to the standards and technology available at the time. These tunnels, lined with concrete or stone, have deteriorated significantly, exhibiting cracks and leaking with water, posing engineering and safety risks.

The Bãi Gió Tunnel (Khánh Hòa Province) and Chí Thạnh Tunnel (Phú Yên Province) were undergoing repairs and upgrades when large landslides occurred. Lê Quang Vinh, Director of Phú Khánh Railway Operation Branch, said that the causes of the landslides at both tunnels were similar, both relating to their age.

Along the North-South railway, other tunnels have also started to show signs of decline, affecting train safety. Vietnam News Agency reporters recorded the condition at tunnel number 14 (passing through the Hải Vân Pass area, Liên Chiểu District, Đà Nẵng City) with a length of over 940m.

Inside the tunnel, there is weathering and signs of dilapidation, with pervasive seepage and wetness. The concrete ceiling of the tunnel has many cracks, with water flowing down in streams.

In the middle of the tunnel there is a stretch of about 100m without a concrete arch, only a natural stone arch, while down both sides, alcove safety areas where you can step off the tracks when trains pass, are full of water.

Trần Thiện Cảnh, Director of the Việt Nam Railway Authority (VNRA), noted that during reinforcement and repairs, the engineering units did not fully anticipate what was at stake.

The landslide occurred at a point that was not a probe drill point, resulting in the tunnel lining breaking. This incident underscores the need for experience to be gained for future repairs, including reinforcing and consolidating a tunnel ceiling before drilling to avoid landslides.

In reality, during the repair of most tunnels, landslides occur but on a smaller scale. However, the tunnels in the South Central region, such as Bãi Gió and Chí Thạnh tunnels, have complex geological conditions, leading to larger landslides.

Tunnel No 14 in Hải Vân Pass. There are dozens of trains crossing this tunnel daily. VNA/VNS Photo Quốc Dũng.

Double Damage

The landslides at the Bãi Gió and Chí Thạnh railway tunnels caused a significant delays on the the North-South railway line, resulting in substantial losses for production, business and tourism activities.

According to Vietnam Railways (VNR), the total damage caused to the railway sector was nearly VNĐ50 billion (US$1.9 million).

Due to the landslide at the Chí Thạnh Tunnel, the railways had to transfer tens of thousands of passengers onto coaches to ensure their journey continued. Passengers were assisted in travelling between Tuy Hòa Station (Tuy Hòa City) and La Hai Station (Đồng Xuân District) in Phú Yên Province, a distance of nearly 50km.

VNR cancelled several trains, from May 23 to May 30. Additionally, the railway sector temporarily halted ten freight trains on the North-South railway line, while other vehicles were forced to take alternate routes as directed by local traffic police.

According to Lê Quang Vinh, Director of Phú Khánh Railway Operation Branch, after the Chí Thạnh railway tunnel landslide, the unit had to mobilise maximum resources to focus on repair work.

Not only are there economic losses, but the continuous occurrence of tunnel landslides also undermines public confidence in the quality of service and safety when travelling by train.

Nguyễn Văn Trung, a passenger travelling by train from Hồ Chí Minh City to Nghệ An province, encountered the Chí Thạnh tunnel landslide at Tuy Hòa Station and had to continue his journey on a coach. Although he was sympathetic to the operators, Trung voiced his concern as two railway tunnel landslides occurred consecutively in Khánh Hòa and Phú Yên provinces recently. He worried that if a landslide occurred while a train was passing through the tunnel, the consequences would be much more severe.

A worker directing trains in Giã Station in Khánh Hoà. VNA/VNS Photo Đặng Tuấn

A long-term solution

After determining the causes of the landslides at the Chí Thạnh and Bãi Gió railway tunnels, various remedial solutions were proposed by experts to quickly reopen the tunnels and resume transportation activities.

Nguyễn Thanh Hoài, Director of Project Management Board 85, stated that monitoring and assessing geological conditions at railway tunnels is essential to prevent future landslides. Specialised agencies will evaluate and forecast geological changes and landslide risks at tunnel sections and there will be a proactive review and maintenance plans for degraded tunnels at the highest risk of landslides.

The Vietnam Railway Authority has been gradually reinforcing and renovating several tunnels, including those in the Hải Vân Pass area funded by the French government. Despite these efforts, twelve tunnels on the North-South railway line remain dilapidated and are scheduled to be repaired shortly. In addition to promptly repairing railway tunnels, the operational management unit also actively implements safety solutions for train operations.

Hoàng Anh Dũng, Deputy Director of Quảng Nam-Đà Nẵng Railway JSC, which manages the railway system through Đà Nẵng, Quảng Nam, and Quảng Ngãi, said that his company has overhauled the railway structure in Tunnel No 14 and built drainage systems on both sides of the tunnel walls to minimise damage from leaking groundwater. However, as repairing and upgrading the tunnel walls and arches requires specialised expertise and substantial funding, Dũng suggested higher authorities research and find solutions.

Ensuring smooth traffic through the Bãi Gió and Chí Thạnh tunnels is just the beginning. The Ministry of Transport and VNR are continuing geological surveys and and trying to find long-term solutions to ensure tunnel safety. In addition, a workshop will be organised to evaluate the current situation and consult with experts on remedial measures.

Đặng Sỹ Mạnh, Chairman of the Members' Council of VNR, emphasised the importance of proactive measures and taking an inventory of all old railway bridges and tunnels, so they can be reinforced if needed, before they become a problem.

On February 28, 2023, the Politburo issued a document outlining the development of Việt Nam's railway system, with the primary goal being building a robust national network, across urban railways and making a North-South high-speed railway a backbone to all operations.

It will connect up urban railway lines, major economic centres, domestic transport hubs (seaports, international airports) and international transits.

The Ministry of Transport has been seriously studying the investment in a high-speed railway on the North-South axis for some time.

In 2011, the Ministry of Transport proposed to the Politburo an investment plan for a North-South high-speed railway at a total cost of over US$67 billion. However, due to insufficient funding at that time, the Ministry of Transport could not proceed.

"It's believed that Việt Nam has sufficient resources to build a North-South high-speed railway with electrification. This is the only feasible green transport method, suitable for climate change adaptation, contributing to reducing carbon emissions to zero and promoting the development of a green economy," said Deputy Minister of Transport Nguyễn Danh Huy.

However it is true that compared to other modes of transport, the railway is being 'left behind' due to its outdated technical infrastructure, the recent consecutive landslides being a prime example.

Therefore, the Party and the State's direction to invest in a modern railway line ensures a fundamental, sustainable solution for the continuous operation of trains on the North-South railway line. VNS