An armed police officer of the 8th brigade of the Lhasa Detachment of the People's Armed Police of the Xizang Autonomous Region stands on duty. (Photo: Liu Caiyu/GT)

The carriages of trains sped through the tunnel in front of Zechim Yoindain as he raised his hand in salute.

Before him stood the Yangbajing Tunnel of the Qinghai-Xizang Railway, a structure he has diligently guarded in the past five years.

Spanning a total length of 1,956 kilometers, the Qinghai-Xizang Railway is the world's highest railway built on permafrost and boasts the longest plateau route. Since its completion and opening to traffic in 2006, armed police officers of the 8th brigade of the Lhasa Detachment of the People's Armed Police of the Xizang Autonomous Region have dedicated themselves to the snowy plateau.

Zechim Yoindain, originally from Qamdo, recalled his thoughts when he first arrived at the Yangbajing Tunnel Group on the desolate hillside. Gazing at the bare mountains and the sparsely populated road ahead, he couldn't help but reflect deeply. "It was such a barren area that I had no idea what to expect. Are there still mountains like this in Xizang? What is the value of my commitment to the military?"

Nestled in a remote valley among the mountains of Dangxiong county, Lhasa, armed police officers stationed here endure heavy winds year-round. It is not surprising that their skins often get dislodged in winter due to the relentless gusts and extreme cold.

Occasionally, tourists aboard the trains would wave to Zechim Yoindain. "Watching them safely pass through the tunnel to reach their destinations makes me feel that every effort has been worthwhile," he said, a sense of fulfillment evident in his voice.

Xizang remains socially stable, and incidents of intentional damage to the railway are rare, according to armed police officers interviewed by the Global Times. However, other challenges do exist.

In one instance, heavy rain during the rainy season caused mudslides that reached the camp area. Fortunately, the tunnel remained largely unaffected.

It is crucial if a mudslide or any natural disaster affects the tracks, trains must stop immediately; otherwise, continuing operations could lead to accidents, He Sijiang, the head of the 26th squadron, told the Global Times. "If anything goes wrong, the whole traffic will be paralyzed."

After that incident, mountains along the railway had been reinforced, and protective nets were installed to prevent mudslides, preventing excessive rain from washing debris down, He said.

Currently, the biggest challenge in protecting the railway comes from wildlife. As the ecology in Xizang improves, wildlife is becoming more abundant, and preventing the accidental jump of wild dogs or nomad yaks onto the tracks is one of their priorities.

One early morning, a deer weighing 200 to 300 pounds, resembling a cow, jumped onto the tracks. It leaped over the fence along the tracks, taking advantage of the sloped terrain, which allowed it to jump high without triggering an alarm.

The emergency team quickly spotted the deer and promptly drove it away, said He. As He spoke to the Global Times, swarms of yaks can be seen grazing on the mountain along the tunnel.

To ease their daily monitoring efforts, the squadron has installed vibration-sensitive fiber optic cables. Typically, when someone or animals cross the fence, the cables are able to detect the vibrations, immediately sound an alarm, and transmit the footage to the duty room.

Sentinels are required to maintain a 24-hour watch at their posts, and the use of advanced technology helps armed police officers quickly identify and respond to any intrusions, He noted. "Even a single fly buzzing by can trigger an alarm."

Such digital equipment has also been installed on both sides of the Lhasa River Super-Long Bridge — the "last bridge" on the Qinghai-Xizang Railway — where another squadron, the 25th squadron from the Lhasa Detachment of the Xizang Armed Police is stationed.

"Sometimes at night, when the sentinels feel particularly tired and their alertness wanes, the monitoring personnel can remind each other through the installed cameras," said Sonam Tsetan, the head of the 25th squadron.

When armed police officers devote most of their time and energy to guarding the railway, their personal life often becomes an afterthought. "Separation is the norm; meet-ups are accidental," said Yang Bin, the head of the 8th brigade of the Lhasa Detachment.

Recently, one of Yang's children caught a cold, and his wife took the child to the hospital alone while their other child stayed at home. "They have to understand and get used to it."

Sacrificing the little family for the nation is the norm for every armed police officer guarding the railway - the lifeblood of Xizang and the stability factor of the entire region, Yang added.

In 2006, the Qinghai-Xizang Railway officially opened to traffic, marking the end of Xizang's isolation from the railway network. In the past 18 years, the Qinghai-Xizang Railway has transported a total of 37.6223 million passenger trips to and from Xizang and 8.92537 million tons of cargo in and out of Xizang, as of August 30.

This transformative period has also seen a dramatic rise in Xizang's economic and social development. The region's GDP has skyrocketed from 34.2 billion yuan ($4.8 billion) in 2006 to 239.267 billion yuan in 2023.

Phuntsog Tsring, a deputy head of the 25th squadron and a native of Xigaze, fondly recalled the first time he encountered a dragon fruit, which had been a mystery to them all. Xizang, once limited in its offerings, has blossomed since the introduction of train services, allowing locals to access exotic fruits and products at their convenience.

"As everyone's life becomes more prosperous, it enhances the sense of value and happiness we derive from our responsibilities in safeguarding our tasks," Phuntsog Tsring reflects.

Each morning, the rhythmic sound of wheels clattering against the tracks fuels Zechim Yoindain's determination to advance in his career.

"I will continue to guard it," he vows, embodying the determination of the armed police officer to take root in the plateau and defend China's border areas.