On steep karst cliffs above the Xianggui railway, a small team of maintenance climbers perform work that looks part mountaineering, part census-taking. They inspect, measure, mark and sometimes physically move boulders that could dislodge onto tracks used by China–Vietnam freight and passenger services, methodically recording each hazard in a database technicians call “giving stones household registration.”
The stretch lies on the Nanning section of the Xianggui line, a key international rail corridor connecting China and Vietnam. The terrain is classic karst — jagged limestone peaks, near-vertical walls and deep fissures — and it becomes especially sensitive during the Spring Festival travel rush when passenger and cross-border freight traffic intensifies.
Teams known locally as the “climbing tigers” combine low-tech grit with modern sensing: they dispatch drones running AI-enabled scans to flag suspect blocks, then haul dozens of kilos of rope and safety hardware up cliffs to verify and treat each point. Work must be done in narrow safety windows when no trains are due, and often requires edging along nets and webbing on faces so steep climbers can steady a single toe while cutting roots or uprooting saplings that widen cracks.
Inspection procedures are systematic. Crews check active and passive catch nets for corrosion or loose anchors, measure fissures against previous records to detect widening or movement, and mark new suspect stones with red paint so the next drone sweep can locate them quickly. Where loosening indicates immediate danger they either stabilise the rock in place or remove it and record the action as a closed case — bureaucratically “de-registering” the hazard.
The human cost of that precision is visible: long days hauling 30–40 kilogram packs, dealing with venomous insects, red imported fire ants and snakes, and snatching scarce rests of bread and water on narrow ledges. Team leader Yang Fadeng, 31, and colleagues in their early twenties, take pride in small victories — watching a train glide past a point they have secured gives them the clearest proof their risks were worth taking.
The operation illustrates a wider challenge for China’s rail network. Maintaining safety on older international corridors that traverse complex geology requires a mix of labour-intensive fieldwork, remote sensing and administrative rigor. Drones and AI help prioritise targets, but cliffside work remains hard and hazardous, and records and rapid marking systems are crucial to ensure continuity between inspections.
For cross-border commerce and passenger mobility, the stakes are practical and strategic: a single rockfall could disrupt international freight flows, delay passengers during peak travel periods, and impose reputational and financial costs. As extreme weather events grow more frequent, and as China pushes to expand international rail links, the demand for such inspection regimes — and for investment in predictive monitoring and stronger passive defences — is likely to increase.
The daily routine of the climbing tigers therefore speaks to both the micro and the macro: to the tactile, painstaking work required to keep trains moving safely today, and to the broader imperative of modernising infrastructure maintenance for a future in which more traffic, and more volatile weather, raise the cost of doing nothing.