The completion of the Tibet railway, the longest high-altitude railway in the world, is being hailed in China as one of the world's great engineering marvels.

The arrival of the railway will bring tremendous change. China's rulers say it will open up Tibet, bringing greater prosperity for its entire people. Detractors say the opening of the railway will be the end of an independent Tibetan culture. Environmentalists worry about what effect the railway will have on the migration routes of rare Tibetan antelope, and about a fragile ecosystem that, once damaged, will take generations to repair.

Gueorgui...