A new rail link to Tibet, to be unveiled this weekend, will navigate 16,500-foot passes using systems to stabilize tracks over permafrost and cabins with enriched oxygen to help passengers deal with high altitudes. Despite the engineering ingenuity of the new train, the link has not been without controversy. The 710-mile railway has been criticized as part of Beijing's campaign to crush Tibetan culture while environmentalists worry about the railway's impact on the highlands. Railway officials were quick to defend the train, saying it will help improve economic links and teach more people about Tibet's unique culture. A railway official said few Tibetans would work on the train at first.