Roof of the world on rails

Roof of the world on rails The Qinghai-Tibet railway, one of the nation's most challenging feats of modern engineering, is already in its seventh year of operation following an almost 90-year wait for the line to become a reality. First proposed by the founder of modern China, Dr Sun Yat-sen, in his 1917-1920 plan for the national rail network, it today holds the title of the world's highest railway and runs through some of the most inhospitable yet beautiful terrain known to man. Map key: O- Station - Scenery viewing platform --..... Railway construction in progress Haixi Tianjun Gangca Haiyan Xinjiang Uygur Autonomous Region Ulan Xining Qinghai Golmud Lake Nanshankoud Lanzhou Xiaonanchuan od Ganlong Wangkungd Nachitai Yuzhufeng TIBETAN PLATEAU Kekexili Nature Chumaerhe Budongquan Reserve Wudaoliang Xiushuihed Gansu province Jiangkedong Qinghai province Riachiquo Bayan Har Mountains TIBETAN PLATEAU Tuotuohe Tongtianhe Yanshiping Buqiangge Tibet Autonomous Region Tanggula Highest point of the track 5,068m Yushu Sichuan province Zhajiazangbud 8 Tuoju Amdo Connections from other cities Cuonahu Lake Siling Co Gangxiu Diwuma Nagqu Tuoru Beijingo Namucuo Lake OGuluzhen Wumatangxiang Damxung Golmud Lanzhóu Mount Nyenchen Tanglha a 7,162m o Yangbajingzhen Dagiongguo Xining Xining-Lhasa railway Shanghai Chengdu Maxiang Nyingchi Lhasa Chongging Lhasa Yarlung Zangbo River Shigatse Guangzhou The journey from Xining takes about 24 hours Tanggula World's highest section of railway Railway altitude Metres above sea Amdo 5,000 Lhasa 4,500 - 4,000 - Xining 3,500 Golmud 3,000 2,500 2,000 1.500 1,000 - 500 Permafrost zone 0- 100km 200 300 400 500 600 700 800 900 1,000 1,100 1,200 1.300 1.400 1,500 1,600 1,700 1,800 1,900 The permafrost problem Permafrost is ground that is permanently frozen due to it remaining at or below zero degrees Celsius for more than two years. It is widespread on the Tibetan Plateau due to the low temperatures there. Heat froma railway can thaw permafrost, making the ground unstable for the track, so some sections of the railway are elevated to keep them away from the ground, while others are insulated. Elevated sections Three layers of embankment - Ground lying over the permanent ice is very unstable when there is any temperature change The gaps between columns provide air flow that cools the ground Track Compact sand layer Winter -350C Metal sun shades block solar radiation and reflect heat Summer +30°C When the viaduct was built, the holes Even when the permafrost Stone were filled with fresh concrete, which melts in summer the pillars freezes quickly to the same temperature as the permafrost layer remain frozen and maintain the lower temperature Wild animals can cross the track without difficulty Railway Thawing Ground becomes unstable Hollow tubes beneath the embankment Pillar create a reverse insulation effect Active layer Insulating ground Active layer Liquid nitrogen Pipes with liquid nitrogen circulating inside cool the ground Permafrost layer Permafrost layer - Frozen pillar Pillar still frozen Permafrost Permanent ice layer common in Arctic zones and the Tibetan Plateau Under permafrost is a large amount of the greenhouse gas methane. Any thawing releases this gas into the atmosphere, fuelling climate change Ventilation systems draw in air and release nitrogen outside while oxygen is pumped in the compartments Sealed windows and sliding doors minimise oxygen loss The train Three diesel-powered engines Over 80 per cent of the journey from Golmud is at altitudes above 4,000 metres, so the passen- gers sometimes need oxygen supply NJ2-class General Electric Power output 3,800 kW Weight Max speed 138 tonnes 120km/h (100km/h at permafrost areas) Tube into nostrils Oxygen Coated window glass blocks UV rays Tube connected to oxygen supply Underbellies that protect the wiring from sand and dust storms- Can carry 15 carriages ........ Sources: China Tibet Train, Discovery Channel SCMP Graphic: Adolfo Arranz