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Environment: Riding on the roof of the world

October 11, 2007

Nature   449 , 398-402 (27 September 2007)

Jane Qiu  (Jane Qiu is a freelance writer based in Beijing and London)

Tt is a glorious, crispy cold summer morning on the Qinghai-Tibet 
plateau,
and already my lips are turning purple. At more than 4,500 metres 
above sea
level, the air is thin and I can feel a light headache coming on. In 
front
of me a pair of rail tracks stretch into the distance, looking as 
thin as
silver threads as they negotiate a landscape filled by expansive 
glaciers
and mountains with needle-sharp peaks.

The rattling sound of an approaching train jolts me to alertness and 
in no
time it roars past us at 100 kilometres an hour, passengers waving
gleefully from its windows. I'm painfully aware that the pressurized air
behind those windows offers a great deal more oxygen than the stuff I'm
breathing in the open air. "You will be fine," my Tibetan host, Tsega,
pronounces after inspecting me up and down a few times. I feel 
obliged to
trust his judgement.

The railway in front of me is the world's highest, and is a 1,142-
kilometre
stretch that connects Golmud, in China's Qinghai province, with Lhasa,
capital of the Tibet Autonomous Region. It is also widely regarded as 
one
of the great engineering achievements of the world. Its course 
crosses four
mountain chains and five major rivers - with nearly all of it more than
4,000 metres above sea level. Successive Chinese governments, keen to
tighten their grip on Tibet, have dreamed of such a railway for 
nearly half
a century, and more than 20,000 workers laboured for 5 years to complete
the project at a cost of 33 billion yuan (about US$4 billion).

Now, more than a year after it opened, the railway remains a source of
bitter controversy. Supporters say the scheme will bring major
opportunities to China's underdeveloped west. Critics fear that China 
will
use it to assert control over a contested border region, and to 
exploit its
natural resources. The railway's long-term impacts on the plateau - 
direct
and indirect - remain unknown, and I have embarked on a journey between
Golmud and Lhasa - sometimes on the train, sometimes off it - to seek
answers. The trip reveals how well the engineering is standing up 
after a
year's worth of exposure to the harsh seasons; how the attempts to 
minimize
its environmental effects have fared; and what the railway means to
ordinary Tibetans.

Earthquakes and permafrost

Tsega, who runs the Kekexili nature reserve from the office in 
Golmud, has
kindly agreed to take me along on one of his regular surveillance 
trips to
the reserve. After driving for 100 kilometres, we approach the gigantic
Kunlun fault, a 430-kilometre surface rupture, ripped open by a
magnitude-8.1 earthquake 1  on 14 November 2001. The scar from that 
quake
is clearly visible in the landscape, and sends a shiver down my spine 
as we
drive across it.

The earthquake didn't cause much damage to the railway because 
construction
had just started, says Wang Lanming, director of the Lanzhou 
Institute of
Seismology, China Earthquake Administration, in Gansu province. "But 
it was
certainly a wake-up call for those of us involved in advising the 
engineers
of the region's seismic activity," he adds. Two other quakes of 
magnitude
7.5 or greater have shaken the plateau in the past century, and seismic
activity poses one of the major threats to the new railway.
The question is what to do about it. Railway engineers have avoided
building stations, tunnels and bridges in areas containing active 
faults,
and these main structures are equipped with anti-quake safety 
measures such
as additional steel reinforcement bars to keep the concrete from 
cracking
during an earthquake. But the tracks themselves do not have any extra
reinforcement. "The cost would be astronomical to install anti-quake
measures all through the route," says Wang.

However, researchers and engineers are in talks with the ministry of
railways about installing an earthquake-detection system along the 
tracks
on the plateau. The project, estimated to cost tens of millions of yuan,
could, in theory, notify the train of a substantial earthquake in 
progress
by detecting the primary seismic waves propagating from a quake, then
bringing the train to a halt before the damaging secondary waves 
arrive. As
Wang notes, stopping a train before it derails in a quake is 
particularly
important for high-altitude railways: "It would be very dangerous if
passengers were exposed to the harsh conditions of the Qinghai-Tibet
plateau," he says.

The harsh weather here also calls for innovative approaches to railway
engineering. As we crest the Kunlun Range, ahead of us we see how the 
rail
tracks disappear into a 1.6-kilometre-long tunnel. "We are entering a
region rich with warm permafrost," Tsega explains. The temperature of 
warm
permafrost stays within a couple of degrees below freezing, and its top
layer thaws more readily in the summer than that of normal permafrost,
making the ground more unstable.

Regular permafrost is bad enough; engineers have to raise the railbed or
use insulating materials to keep the tracks from warping during seasonal
freeze-thaw cycles. Construction is even harder with the mix of 
permafrost
types on the Qinghai-Tibet plateau. The railway traverses 275 
kilometres of
warm permafrost, 221 kilometres of ice-rich permafrost, and 134 
kilometres
of a mix of both. "This is the worst combination for any permafrost
engineering project," says Max Brewer, a permafrost researcher at the
University of Alaska in Fairbanks.

Keeping cool

A group of researchers, led by Cheng Guodong of the Cold and Arid 
Regions
Environmental and Engineering Research Institute, Chinese Academy of
Sciences, in Lanzhou, has developed a series of measures to cool down 
the
railbed. All the approaches capitalize on using the benefits of the cold
environment, and try to keep the railbed as naturally cold as 
possible 2 .

In most places, for instance, the railway embankment is raised by 
between 2
metres and 10 metres, helping insulate the ground from the heat 
created by
the tracks. The slopes of the embankment are also covered with a 
layer of
crushed rocks - a technique inspired by reports that permafrost can 
occur
beneath blocky and coarse materials even when the air temperature is 
well
above 0 °C. "This is the first time a large-scale project has used the
technique as one of its primary solutions," says Zhang Tingjun, a
permafrost researcher at the National Snow and Ice Data Center in 
Boulder,
Colorado. It seems to be working; tests suggest that the crushed layer
keeps temperatures up to 2 °C cooler, and in some places, the permafrost
has even increased in volume and pushed up into the embankment 
structure.

As we drive along, passing Tibetan wild asses grazing by the road, I 
spot
other gadgets along the tracks for cooling the embankment. The most
prominent ones are 'thermosyphons' - a series of thin metal tubes 
standing
upright on the railbed shoulders every 3 metres, which use evaporative
cooling to transfer heat from one end to another. Thermosyphons are 
costly
to install and maintain, but the Chinese government is not shy in 
lavishing
on such gimmicks, with 18,200 of them installed in 'high-risk' 
permafrost
areas.

Tang Gu La, at 5,068 metres above sea level, is the world's highest 
train
station.
Elsewhere, engineers buried ventilation pipes through the embankments,
which can also cool the temperature by up to 2 °C. And some of the
south-facing slopes hold giant shading-boards. Over the first winter, 
these
allowed shaded areas to freeze solid while non-shaded embankments 
remained
unfrozen.

More than 200 sensors constantly monitor ground temperatures on both 
sides
of the railbed over permafrost regions, in a system costing 40 million
yuan. One year and a seasonal cycle on, researchers suggest that the
permafrost regions are recovering from the disturbance caused during the
construction of the railway. But there have been several cracks along 
the
track in some regions, which may be due to distorted foundations. Cracks
are repaired as soon as they are discovered by the crew regularly
monitoring the track. Zhang Luxin, chief engineer for construction and
maintenance of the railway, would not disclose the total number of 
cracks
since it began operating. But he says that all of the cracks so far have
been superficial and have had no impact on the railbed.

Max Brewer says he is not alarmed by such incidents. "It would be 
naive to
expect that construction of this scale could be free of problems," he 
says.
Indeed, it has been more than a century since Siberia's first railway 
was
built, but frost-damage still affects 30% of the tracks passing across
permafrost regions, according to a recent survey conducted by Russian
engineers.

Some experts, however, fear that the problems could get worse in a 
warmer
climate. Research shows that global warming has affected the ground
temperature on the plateau to a depth of 40 metres; permafrost is 
degrading
as temperatures rise and the 'active' layer that freezes and thaws every
year gets thicker 3 . According to a recent report by the Chinese 
Academy
of Sciences, 10% of the permafrost regions on the plateau have 
degraded in
the past 20 years.

Before 2001, when the railway constuction started, the consensus was 
that
the air temperature on the plateau would increase by 1 °C over the 
next 50
years. Scientists now think that it may rise by 2.2-2.6 °C during that
time. Cheng, however, says that engineers could adapt the railways to
additional temperature increases by adding more of the cooling 
measures to
the railbed's slopes.

Lack of oxygen sends excruciating pulses burrowing in through the top 
of my
head and deep into my brain. I turn to the view outside, seeking 
comfort in
the widening, sparsely vegetated valley, sprinkled with streams, 
rivers and
enormous alluvial fans. In the distance, my gaze comes to rest on a
gigantic overpass perching high above the plain. "That's the famous
Qingshuihe Bridge," Tsega says, noticing my sudden enthusiasm. The
11.7-kilometre-long overpass, consisting of 1,367 piers and costing 24
million yuan to build, straddles the most unstable stretch of permafrost
along the railway. The overpass removes direct contact between 
permafrost
and the tracks - the engineers' last resort for protecting fragile 
ground.

Effect on migration

Tsega explains that the bridge is also one of 33 passageways designed to
enable wildlife on the plateau to go under the arches to get from one 
side
of the railway to the other. Chiru, endangered Tibetan antelopes 
known for
their speed and stamina, are shy creatures and particularly prone to
disturbances. Every June, more than 3,000 pregnant chiru travel 
hundreds of
kilometres westward from the Three-River Headwater nature reserve to 
give
birth in the Kekexili reserve, then migrate back with their young in
August. Both the Qinghai-Tibet railway, and the highway that follows the
same route, cut right across their migratory paths.

Experts are divided on the subject of how effective such wildlife
passageways are. According to a government report released ahead of the
first anniversary of the line's operation in July, most of the 
passageways
are used by plateau animals and the railway has had no impact on the
Tibetan antelopes in those areas. Other research is less positive. 
Contrary
to reports by the state-run Chinese media, as many as 1,500 antelopes
couldn't make the crossing in 2003 and had to give birth locally, 
says Yang
Xin, president of Green River, a non-governmental organization based in
Chengdu, Sichuan province. This happened despite the fact that railway
workers suspended construction and cleared out of the sites for a 
couple of
days during the animals' peak migration period.

Although antelopes are able to cross the railway, research by Yang 
and Su
Jianping, a zoologist at the Northwest Institute of Plateau Biology,
Chinese Academy of Sciences, in Xining, Qinghai province, suggests that
antelopes don't use most of the passageways. Before the railway
construction began, antelopes crossed the highway between the Kunlun 
Pass
and Wudaoliang at multiple locations along a 100-kilometre stretch. 
Now, a
large majority of them funnel under the 200-metre-long overpass at the
Wubei Bridge, just north of Wudaoliang.

It's not yet clear what these changes in the animals' migration habits
might mean in the long term. The researchers conjecture that some of the
new overpasses might be too low or narrow for animals to feel 
comfortable,
which pushes them into new migration routes. Yang, for instance, has 
seen
herds of antelope approaching the Chumaer River - which used to be a key
crossing site - then hesitate, turn away and go south to make the 
crossing
near Wudaoliang.

Knowing why some overpasses seem to work better than others could be
valuable for future construction work, says Su - but only long-term
monitoring can find that out. "It would be surprising if the highway and
railway didn't affect movements of plateau animals," he says. "It's 
unclear
how this could affect their other behaviours or their survival as a
species." Yang Qisen of the Beijing-based Institute of Zoology - 
leader of
the team that studies the railway's impact on plateau wildlife - 
declined
Nature 's request for an interview.

Throughout the journey, the plateau is otherwise little marred by
construction debris or the landscape scars usually associated with major
projects. Railway planners developed a 'green policy' to ensure 
protection
for soil, vegetation, animals and water resources along the route 4 .
Nearly 4% of the 33 billion yuan spent on construction was allocated to
restoration of ecosystems and environmental protection, according to Hao
Qingjun, an official at the Xining-based Qinghai Environmental 
Protection
Agency. Where possible, the railway was rerouted around sensitive 
natural
zones such as wetlands. In other places, much of the turf that was 
dug up
during the construction phase was preserved and then replanted once that
section of the railway was completed.

Accumulating rubbish

The sun has almost set by the time we pull off the road at the reserve's
protection station near Tuotuohe for the last stop of the day. The
lingering light sets the snow-capped mountain peaks ablaze, while 
long blue
shadows creep down from their dark stony slopes.

Tuotuohe, a main town along the railway, lies in the region that is the
headwater of three of Asia's largest rivers - the Yangtze, Yellow and
Lancang (Mekong) rivers. Standing at the Tuotuohe Bridge, the first 
bridge
over the Yangtze, I recall how Yang told me that the town is also the 
first
rubbish dump along the river. The highway and railway are bringing more
people and industrial products to the plateau. They have also led to 
more
roads and other constructions, such as hotels and restaurants, along the
route. "Those constructions do not have the same kind of resources as 
the
railway project," says Yang, referring to the lack of money and 
manpower.
"So environmental protection is not on the agenda."

Few towns along the route have the capacity to treat their accumulating
rubbish, so it is left to moulder in open containers on the street and
along the river banks. This is not only a source of disease, says 
Yang, but
it also pollutes the environment and endangers wildlife. In addition, 
the
introduction of commerce into the plateau life has led to an increasing
need for more livestock, such as yaks, cows and sheep, which nomads can
exchange for industrial products. "Over-grazing is a serious problem 
on the
plateau," he says. In the Three-River Headwater region, some nomads 
have to
go as high as 5,500 metres to find fresh pasture for their animals.

Change in Tibet

It soon turns pitch-dark and the temperature drops sharply. In the
protection station we sit around a stove, enjoying the waves of 
warmth it
radiates. A television is showing news on Phoenix TV, a popular Hong 
Kong
channel. There is a computer in the corner with an internet connection.
Tashi, a young Tibetan man who looks after the station, brings us 
supper:
bread, yoghurt and Tibetan tea, along with some dried beef Tsega brought
with us. Over the meal, I ask Tashi how the railway has affected his 
life
and that of his family who are nomads in the region. "Our life is 
still the
same," he says after a moment of hesitation, a sense of indifference
palpable. None of his family or any of their friends sees a need for 
taking
the train. "We are nomads."

His indifference, and that of many others living in rural Tibet, is in
stark contrast to China's claimed purpose of the railway: to promote
economic development. On the surface, Tibet is doing well, and the 
railway
has certainly helped; during the first 10 months of its operation, trade
between Tibet and outside regions increased by 75%, to 2.6 billion yuan.
Tibet will receive an estimated 3 million tourists this year and, by 
2010,
the number is expected to reach 5 million.

The billions of yuan that Beijing has poured into Tibet flow almost
exclusively along the handful of roads in the region, pooling in the 
towns
along the way and finally ending up in three major cities - Lhasa, 
Shigatse
and Chamdo, says Kabir Heimsath, a Lhasa-based anthropologist at St 
Cross
College, University of Oxford. The towns and cities are the few 
places in
which serious development has taken hold and, consequently, are also the
only places where Han migrants - mostly itinerant workers 
marginalized by
the same system in other parts of China - and businessmen form a 
majority.
This increasing disparity between the urban rich and the rural poor - a
general problem of China's economic development - means that most 
Tibetans
are left behind, unable to reap the benefits of modernization, he says.

Even in towns and cities, Tibetans are in danger of being marginalized.
They find it increasingly difficult to compete in the job market against
skilled and more business-oriented Han, who, privileged by ethnicity and
language, make up more than 92% of the population of China. 
Intentionally
or not, Tibet has seen a surge of Han migrants, which is further 
boosted by
the railway. And emerging with this wave of migration is the cultural
imprint of Han Chinese on many aspects of Tibetan life - even 
religion, as
an increasing number of Tibetan monasteries are funded and built by Han
Chinese.

On the train

A few days after visiting Tuotuohe, I board the train from Golmud to 
Lhasa
for the uninterrupted experience of the entire train journey. The 
coaches
are completely sealed so no rubbish can be thrown out and have a
wastewater-storage system. They have windows with ultraviolet filters to
keep out the sun's glare, and their underbellies are enclosed to protect
wiring from snowstorms and sandstorms. The oxygen level in every 
coach is
well-adjusted, and additionally, passengers can plug in to the oxygen
supply anywhere on the train. Every coach is equipped with digital 
displays
that show continuous updates of the train's elevation and speed, the
outside temperature and the distance to the next station.

Travelling at about 100 kilometres an hour, the trip is surprisingly
smooth. I have the opportunity to review the scenery - the magnificent
Mount Yuzhu reaching up to 6,178 metres, the turquoise Namucuo Lake
shimmering under the unearthly Tibetan light, nomads dressed in 
colourful
robes, turrets with red, blue and green prayer flags fluttering near a
Communist flag. Fourteen hours later, at the end of an uneventful 
journey,
the train pulls into the great vault of Lhasa's new railway station.

The next morning I wander through the city's various districts. Apart 
from
the Tibetan quarter centred on the holiest Jokang temple, most of the
shops, hotels and restaurants are run by Han Chinese. I come across 
Bhuchu,
a Tibetan pilgrim from a village in Sichuan province. He has prostrated
himself on the ground after every step for more than 1,000 kilometres 
over
the past 6 months. Now only steps away from Jokang, he is radiant 
with joy,
hope and a deep sense of heightened existence.

I finally arrive at the Potala Palace, the historic landmark of Lhasa,
which used to be home to successive Dalai Lamas. The sight of the 
gigantic
red-and-white structure perching serenely on Potala Hill is simply
breathtaking. Marvelling at its architectural splendour and spiritual
richness, I can't help but wonder what the railway will bring to 
Tibet and
its people.

Already, China is planning to extend the railway even farther, to 
Zhangmu
to the west and to Dali to the east. Another extension would link 
Shigatse
with Yadong, near the China-India border. What will this expanded 
network
mean for the fragile plateau? Here in the rarefied environment of Lhasa,
the question hangs shimmering in the air.

References

1.     Xu, X., Chen, W., Ma, W., Yu, G. & Chen, G. Seismol. Res. 
Lett. 73,
884-892 (2002).
2.     Cheng, G. Sun, Z. & Niu, F. Cold Reg. Sci. Technol., doi:10.1016
/j.coldregions.2007.02.006 (2007).
3.     Cheng, G. & Wu, T. J. Geophys. Res. 112, F02S03 (2007). |  
Article
|
4.     Peng, C. et al . Science 316, 546-547 (2007). |  Article  |  
PubMed
|  ISI  |  ChemPort  |

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