TANGGULA MOUNTAIN, Tibet, July 1 (Xinhua) -- A passenger train heading for Lanzhou of northwest China's Gansu Province from Lhasa passed the Tanggula Mountain Pass of 5,072 meters above sea level, the highest section of world's railways, at 17:38 Saturday.

The track location is 255 meters higher than the century-old record of world's railway altitude previously kept by Peru at 4,817 meters above sea level for its tracks from the Pacific coast up to Andes.

The Mountains of Tanggula, meaning "mountains on the plateau " in Tibetan, was regarded as "insurmountable even by eagles" in the eyes of locals, where the lowest temperature reach 45 Celsius degree under zero. It is also the source area of the Yangtze River, the longest river in China.

The train, "Tibet 2", carried about 700 passengers with 16 carriages. It will run more than 2,100 kilometers across "the roof of the world" and is expected to arrive at the terminal of Lanzhou in some 30 hours.

Although the oxygen content at the Tanggula Mountain Pass is only 50-60 percent of that at sea level, no passengers on "Tibet 2" felt sick thanks to the oxygen supply on the train, according to Xinhua reporters on the train.

Many passengers took the rare chance to take pictures of the snow-covered mountains while, outside the train, Gyachong, head of the Gangni Town in Amdo County, was leading more than 70 villagers patrolling along the railway.

"I had never expected to see a train traveling across the Tanggula. It is a miracle," said Gyachong.

Tanggula Railway Station, the world's highest at 5,068 meters above sea level, has no stationed workers because of the high altitude.

"The equipment of the station is controlled via the satellite and its operation is also under the eyes of a long-distance monitoring system," said Qin Zhijun, an official with the No. 19 Bureau of the China Railway Group, which is in charge of the station construction.

"Tibet 2" met another passenger train, "Qing 1", which left Golmud for Lhasa this morning, when passing the next stop of Buqiangge at 18:04 Saturday.

Passengers on the two vehicles waving to each other excitedly, which, however, only lasted for a matter of one minute as "Tibet 2" rolled out of the station at a speed more than 80 kilometers without resting.

The Qinghai-Tibet Railway, the world's longest plateau railroad, stretches 1,956 kilometers from Qinghai's provincial capital Xining to Lhasa. The section of 814 km from Xining to Golmud began operation in 1984 and the Golmud-Lhasa section started construction on June 29, 2001.

Experts and builders overcame three difficulties, namely frozen tundra, high altitude and plateau environmental protection, to finish the track-laying of the more challenging Golmud-Lhasa section in last October.

All the railway around the Tanggula Mountain Pass runs on frozen earth, which "poses a major challenge to the railway construction," said La Youyu, deputy director-general of the headquarters for the Qinghai-Tibet Railway construction.

"Frozen earth is vulnerable to climate change, which will thaw in summer and distend the railway base in winter, " La said.

To avoid possible dangers, the deputy director-general said, designers of the railway used technology of heat preservation, slope protection and roadbed ventilation in frozen earth areas.

"The project is not only a magnificent feat in China's history of railway construction, but also a great miracle of the world's railroad history," said Chinese President Hu Jintao when addressing the launching ceremony of the railway Saturday morning. Enditem