They walk in the Wuyi Mountains. CHINA DAILY

The team walks between three stations along the line－Wuyishan North, Nanping and Jian'ou West－all located in the Wuyi Mountains. "Most of the trip involves walking up and down the mountains," Li said.

Their section runs through the Wuyi Mountain National Park, which is home to many animals, including hares, squirrels, as well as rare species such as the red slender loris, macaques and pythons.

To stop animals from crossing the tracks, the team has added a 1-meter-tall metal fence on top of existing protective barriers.

"The standard height for protective barriers along high-speed tracks in China is 2.7 meters, which can stop most animals from jumping onto them in most places. But here in the mountains, animals can jump over the barriers from higher up the slopes, so we've increased the height of the security fence for safety, and also to protect the animals," Li said.

In addition, the grid interval for standard fencing is 10 centimeters, mainly to prevent people from trespassing but the team have added a second layer of fencing with a grid interval of 3.5 cm outside the safety barriers to stop the animals.

"We consulted professionals from the national park about what kind of animals live here. They told us that most are small. We realized the 10 cm gap would not stop small animals from crossing the tracks, so we added the new layer," he said.

The patrolmen make the extra fencing themselves and usually carry seven to eight sections of the fencing during their patrol.

Each section weighs about 10 kilograms. "The metal fencing sometimes gets broken by wild animals and if we don't repair it on time, it leaves a gap for animals to get in," said Xu Hengtao, head of the team.

Thanks to abundant sun and rain, trees grow quickly in the Wuyi Mountains. However, rather than take pleasure in the scenery, the patrolmen view each tree as a potential source of trouble.

"We used to cut down trees that encroached on the network for safety reasons, but now we just trim them to reduce the impact on the environment," another team member, Zhu Qingxin, said.