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Permafrost Warming A Challenge To Tibetian Train Route

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  • Mike Neuman
    Permafrost Warming A Challenge To Tibetian Train Route Boulder CO (SPX) Dec 14, 2004 Engineers constructing a new railroad across the vast, high-altitude
    Message 1 of 1 , Dec 15, 2004
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      Permafrost Warming A Challenge To Tibetian Train Route

      Boulder CO (SPX) Dec 14, 2004
      Engineers constructing a new railroad across the vast, high-altitude
      Tibetan Plateau are using a surprisingly simple idea to fortify
      shifting frozen soils affected by climate warming, according to a
      University of Colorado at Boulder permafrost expert.

      "The Qinghai-Xizang railroad is the most ambitious construction
      project in a permafrost region since the Trans-Alaska Pipeline," said
      CU-Boulder and National Snow and Ice Data Center researcher Tingjun
      Zhang.

      Zhang is working closely on the project with scientists at the Cold
      and Arid Regions Environmental and Engineering Research Institute in
      Lanzhou, China.

      "This is the first time engineers are primarily using crushed rock to
      insulate and fortify a structure against permafrost," he said.

      One example is the Tibetan plateau, where the 695-mile Qinghai-Xizang
      railroad is due to be completed in 2007. More than 600 miles of track
      will be at altitudes of at least 13,000 feet above sea level, and 340
      miles of track will lie across permafrost.

      Zhang will discuss the railroad project and the effects of widespread
      warming and thawing of frozen soils across the northern hemisphere at
      a press briefing in San Francisco Dec. 13 as part of the American
      Geophysical Union's annual meeting.

      He will lead a panel of permafrost and climate experts from
      universities in the United States, Canada and the United Kingdom.
      "If current observations are indicative of long-term trends, we can
      anticipate major changes in permafrost conditions during the next
      century," Zhang said. "Permafrost is thawing in many regions, and it
      is significantly influencing landscapes and ecosystems."

      One example is the Tibetan plateau, where the 695-mile Qinghai-Xizang
      railroad is due to be completed in 2007. More than 600 miles of track
      will be at altitudes of at least 13,000 feet above sea level, and 340
      miles of track will lie across permafrost.

      Half of the permafrost area the tracks will cross is categorized
      as "high- temperature permafrost," Zhang said, meaning that the
      frozen soil is only 1 or 2 degrees Celsius below freezing.

      "The permafrost presents a challenge, because the climate of the area
      is predicted to become warmer during the next 50 to 100 years, and
      construction and train activity on the surface can also create heat
      and cause melting," Zhang said.

      "The shifting soils can ruin railroad tracks, roads and buildings.
      "In order to keep the track straight and the railroad foundation
      stable, engineers are using crushed rock to both insulate and cool
      the permafrost," he said.

      Using on-site experiments and mathematical heat transfer modeling,
      engineers determined that a 2- to 3-foot layer of loose, medium sized
      rocks minimizes heat intake to the soil under railroad embankments
      during warmer months and promotes heat loss in winter.

      "The rock layer is so effective that it actually helps create a net
      cooling effect over time," Zhang said. One experiment detailed in
      Zhang's presentation for the AGU meeting showed the permafrost under
      a railroad embankment was actually colder after a year of crushed
      rock insulation.

      Though crushed rock permafrost insulation was first investigated as
      early as the 1960s, this is the first time a large-scale project is
      using the technique as one of its primary solutions, according to
      Zhang.

      The railroad also is using other means to cool and protect the soil,
      including shading, insulation and "passive heat pumps" comprised of
      piping that conducts heat from the ground and circulates cold air.

      "Crushed rock is the most cost-effective method," Zhang said. "It's
      mainly labor costs." Zhang is a researcher at the National Snow and
      Ice Data Center and the Cooperative Institute for Research in
      Environmental Sciences, both of which are affiliated with CU-Boulder.

      He earned bachelor's and master's degrees in physical geography from
      Lanzhou University in China. He holds master's and doctoral degrees
      in geophysics from the University of Alaska, Fairbanks.

      Zhang is currently the principal investigator on five frozen-ground
      research projects around the world, with funding from the National
      Science Foundation, NASA, the International Arctic Research Center at
      the University of Alaska-Fairbanks and the National Institute for
      Global Environmental Change at the U.S. Department of Energy.
      http://www.spacedaily.com/news/climate-04zzzzf.html
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