Landslides on North-South Railway: Emergency Halts Demand Radical Technological Solutions!

The rockfall incident on March 14 caused a temporary disruption of the North-South railway line through Hai Van Pass.

(Photo: Collected)

On March 15, the Vietnam Railways Corporation was forced to adjust its train schedules starting from 6:00 PM the same day, following a rockfall incident that damaged the tracks at Km768+875. This section passes through the Hai Van Pass within the jurisdiction of Da Nang City. Prior to this, on March 14, two consecutive rockfalls occurred in the same area. The first incident, at approximately 8:00 AM, caused the tracks to buckle and snap, leading to a train derailment as it passed through. By early evening, additional rocks continued to tumble down, forcing the railway sector to temporarily suspend all transport operations through Hai Van Pass and arrange passenger transfers between Da Nang and Lang Co stations. According to a representative from the Vietnam Railway Authority, the site of the incident is near ongoing construction projects at the summit of Hai Van Pass. Excavation activities on the mountainside have generated significant amounts of loose rock and soil, posing a high risk of sliding down onto the tracks if not reinforced or addressed promptly.

Persistent landslide risks on railway routes through mountainous terrain

The North-South railway spans over 1,700km, with many sections traversing mountainous terrain characterized by high, steep cut slopes and complex geological structures. Over long periods of operation, under the impact of natural weathering, prolonged heavy rainfall, and vibrations from passing trains, the soil and rock masses on the slopes easily lose their structural bonding, leading to the risk of landslides or rockfalls onto the tracks. This risk is particularly evident in mountain pass areas, especially during the storm season. Beyond disrupting railway transport operations, these incidents pose significant risks to railway safety.

In this context, handling incidents by clearing fallen rocks and providing temporary reinforcement after each landslide is essentially a short-term response that cannot solve the root of the problem. The core cause lies in the instability of the slope surface, where soil and rock masses have weakened after long-term exposure to weathering, rainwater, gravity, and operational vibrations. Without implementing systematic reinforcement solutions to stabilize the overall slope surface, rockfalls and landslides on the North-South railway will persist, creating an uncontrollable cycle of incidents.

Shifting from incident response to prevention with technological solutions

To reinforce and stabilize steep cut slopes and mitigate the risk of landslides and rockfalls onto the tracks, two typical groups of solutions are currently being applied globally as well as in Vietnam: rigid structures and flexible structures. Rigid solutions typically include measures such as: shotcrete combined with anchors; cement mortar spraying with steel mesh and pins; concrete frames combined with anchors for slope protection; or concrete surface panels.

However, after a period of implementation, many limitations of these solutions have gradually emerged, such as surfaces being prone to damage and fractures, disruption of the natural landscape, and closed solutions failing to address groundwater pressure as well as direct impacts from surface water. On the other hand, a characteristic of these solutions is that when damage occurs, it often appears over a wide area, making repair and restoration difficult in terms of construction equipment, site layout, and the inability to reuse materials for repairs.

In this context, to solve the problem of economic-technical efficiency in slope reinforcement, many projects have shifted to applying "flexible" structural solutions, notably the use of high-tensile steel wire mesh systems combined with anchors and polymer-based triaxial geogrids for surface erosion control.

The application of high-tensile steel wire mesh systems combined with anchors and polymer-based triaxial geogrids for surface erosion control has contributed to stabilizing slopes and ensuring the safety of train operations through the Ru Ri tunnel area (Khanh Hoa).

This solution utilizes high-tensile steel wire mesh integrated with an anchoring system to secure rock masses on the slope surface, thereby mitigating the risk of landslides or rockfalls onto the railway area. Simultaneously, in areas with mixed soil and rock, polymer-based triaxial geogrids are deployed to prevent surface erosion, facilitating the natural growth of vegetation post-construction.

Unlike rigid solutions that lead to the "concretization" of slopes, the flexible solution offers high adaptability to various terrains and does not increase the load on the slope. The mesh structure does not seal the surface, maintaining free drainage, preventing groundwater pressure, and eliminating the need for a separate drainage system for the solution.

The steel mesh system is coated with specialized anti-corrosion technology, allowing for a service life of over 50 years, depending on the environmental installation conditions. Maintenance and repair are also relatively simple: in the event of damage, it only requires replacing specific mesh panels or reusing materials such as surface reinforcement mesh and connection components, thereby saving up to approximately 80% in replacement material costs.

The slope area at section Km1305+950 - Km1306+481 (Ru Ri Pass, Khanh Hoa) after 5 months of applying Vinh Hung's reinforcement solution, with vegetation successfully developing on the slope surface.

Notably, with fast-track construction technology and no requirement for heavy machinery, the installation process does not disrupt train operations on the route.

Video: Reinforcement solution installation does not interrupt train operations  

For certain landslide "black spots" on the North-South railway line, such as the Lac Son and Le Son station areas, slope reinforcement has long faced many difficulties due to rugged terrain and limited access roads, making it nearly impossible to bring heavy machinery and equipment to the site. Under these conditions, traditional reinforcement solutions are often difficult to implement effectively. The flexible structural solution applied by Vinh Hung is therefore considered highly suitable for the actual conditions in these areas, thanks to its lightweight, flexible construction advantages and no requirement for heavy machinery.

Infrastructure safety requires a long-term vision

In the context of climate change increasing the frequency and intensity of extreme weather events—especially prolonged heavy rainfall—the risk of landslides and rockfalls on transport routes passing through mountainous terrain is becoming increasingly evident and difficult to predict. This represents a major challenge for ensuring infrastructure safety, particularly for railway lines traversing complex topography.

Experience shows that focusing solely on incident response after a landslide occurs not only disrupts transport operations but also increases maintenance and recovery costs, while posing numerous risks to railway safety. Therefore, shifting from a "consequence management" mindset to proactive risk prevention through early investment in modern slope reinforcement technologies is becoming an urgent requirement. This approach not only contributes to ensuring the continuity of railway transport operations but is also a necessary step toward building a safe, sustainable infrastructure system that is more resilient to the growing impacts of climate change, thereby firmly protecting the North-South railway—the country's vital transport artery!

Video: Introduction to slope reinforcement and rockfall prevention solutions provided and installed by Vinh Hung