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This utility tunnel in Prague is equipped with railway tracks for maintenance vehicles
This utility tunnel in Prague is equipped with railway tracks for maintenance vehicles
Flin Flon (in Manitoba, Canada) is built on rock, making excavation costly. The utilidor in the foreground carries municipal sewer and water services
Flin Flon (in Manitoba, Canada) is built on rock, making excavation costly. The utilidor in the foreground carries municipal sewer and water services and protects piping from freezing in the winter.
Stark utility tunnel in Zurich, Switzerland
Stark utility tunnel in Zurich, Switzerland
District heating tunnel beneath the Rhein River in Cologne, Germany
District heating tunnel beneath the Rhein River in Cologne, Germany
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Permafrost temperature profile. Permafrost occupies the middle zone, with the active layer above it, while geothermal activity keeps the lowest layer
Permafrost temperature profile. Permafrost occupies the middle zone, with the active layer above it, while geothermal activity keeps the lowest layer above freezing. The vertical 0 °C or 32 °F line denotes the average annual temperature that is crucial for the upper and lower limit of the permafrost zone, while the red lines represent seasonal temperature changes and seasonal temperature extremes. Solid curved lines at the top show seasonal maximum and minimum temperatures in the active layer, while the red dotted-to-solid line depicts the average temperature profile with depth of soil in a permafrost region.
Excavating ice-rich permafrost with a jackhammer in Alaska.
Excavating ice-rich permafrost with a jackhammer in Alaska.
Changes in subsea permafrost extent and structure between the Last Glacial Maximum and now.
Changes in subsea permafrost extent and structure between the Last Glacial Maximum and now.
A group of palsas, as seen from above, formed by the growth of ice lenses.
A group of palsas, as seen from above, formed by the growth of ice lenses.