LHASA, China — China's new train from Beijing to Tibet arrived in the ancient capital of Lhasa Monday, ending its maiden journey after climbing to elevations so high that ballpoint pens and packaged foods burst.

Some passengers breathed oxygen from tubes — many just out of curiosity — as the pressurized train crossed a 16,640-foot pass in Tibet's Tanggula Mountains, a height the Chinese government says makes the $4.2 billion railway the world's highest.

Girls in track suits and traditional Tibetan robes draped white scarves, a customary greeting, on passengers arriving in Lhasa's new railway station.

The train is a new tool in China's much-criticized push to bind its booming east to the Himalayan "roof of the world."

Chinese leaders hope greater prosperity will help to still calls by Tibetans and other ethnic minorities for autonomy from the communist Beijing government.

The line has prompted protests by activists who say it will fuel the influx of Chinese migrants to the isolated region, threatening its ecology and diluting its unique Buddhist culture.

One Tibetan passenger asked a Western reporter what the Dalai Lama, the exiled Tibetan spiritual leader, thought of the train. The man, who asked not to be identified by name, said that with China's Internet monitoring, it was too dangerous for him to search news Web sites for the information himself.

Tibetan antelope and wild donkeys grazed beneath stunning vistas of snowcapped mountains and deep-blue skies as the train rolled through the treeless, sparsely populated area.

China's government says it is spending $190 million on environmental protection along the Golmud-Lhasa stretch of the railway. But despite promises to minimize pollution, the sides of the line were littered with plastic bags, bottles and cardboard boxes. Large sections of the permanently frozen earth were grassless, puddled and scarred by vehicle tracks.

Damaged permafrost "becomes dark, ugly, muddy water," said Daniel Wong, an engineer based in the southern Chinese city of Shenzhen who worked on the trans-Alaska oil pipeline, also laid over permafrost.

"The most unfortunate thing is that such damage will spread," he said.

Trains completed shorter trips on the line between Lhasa and Golmud in Qinghai province while passengers on the 16-car train from the Chinese capital were in the midst of their journey.

State media gave heavy coverage to the railway, with newspapers publishing front-page photos of passengers singing and villagers waving to the passing train. The midday news on state TV showed President Hu Jintao congratulating workers who built the line.

Before the last leg of the trip to Lhasa, the train stopped in Golmud early Monday to switch its standard engine for three powerful locomotives required to haul the train at high altitude.