A train chugs toward a tunnel on the Qinghai-Tibet Plateau, but the sheep and wild donkeys nearby don't seem to be bothered.

The Qinghai-Tibet Railway turns 10 on July 1. According to experts, the environmental impact on plateau wildlife has been contained for better-than-expected results.

"Just days ago, I saw two wild donkeys, only about 15 meters from the tracks as the train passed by. Apparently, the train did not scare them away," said Zhao Xiang, an environmental expert from Shanshui Nature Protection Center, a Beijing-based non-governmental organization.

Most plateau animals are known to be sensitive to disturbance, but many have learned to cope with the environmental changes, said Zhao.

The railway is 1,956 kilometers long and 5,072 meters above sea level at its highest point. In the past decade, a total of 33 animal crossings have been created.

"When the train started operating in 2006, the donkeys and antelopes only came in large hordes and it took quite a while for them to cross via the passages. But they have gotten used to the noise and vibration of trains, and they can cross the passages quite swiftly now," said Dong Weiqi, an engineer with the railway company's design department.

In June, hundreds of Tibetan antelopes, a protected plateau animal, started their annual migration to Zonag Lake at Hol Xil Nature Reserve to give birth.

Back in 2006, when the train started running, only about 2,000 Tibetan antelopes migrated through the passages, but now the number has surpassed 5,000, Dong said. The Tibetan antelope population has recovered to more than 60,000.

The Qinghai-Tibetan plateau has a very fragile environment due to its high elevation, and environmental protection has been a priority.

Gelsang Tashi, an elementary school teacher in Tibet's Nagqu Prefecture, said environmental awareness is taught to children and herders.

"For example, many people take their used plastic bags and batteries along with them when they run errands in the cities so they can properly dispose of the garbage," he said.

Jiang Zehai, deputy manager of the Qinghai-Tibet Railway Company, said they have planted trees along 41 percent of the rail line, covering more than 7.7 million square meters.

A total of 15 sewage processing centers operate along the railway, he said.

"We have held quite strict environmental protection standards in building and operating the railway, because it is our responsibility to keep the environment clean," he said.