Engineering challenge: preserve the permafrost

Engineering challenge: preserve the permafrost. . , Air convection embankments keep the air moving, The rock layers along the sides of Thompson Drive are part of a system known as an air convection embankment. This special type of roadway embankment has large rocks that allow air to circulate. The system is designed so the air circulates more vigorously during cold weather, which results in enhanced cooling of the embankment and the permafrost layer below. This allows the permafrost to survive the warm summer without melting., Air circulation cells form in the embankment and shoulders , Air currents are so strong that they will flow through the snow layers and circulate beneath the pavement. As warm air moves upward it is replaced with colder air from above, providing the cooling that preserves the permafrost., [Diagram of road construction], Constructing the embankment , Uniformly sized rock is used to construct the embankment. Cooling occurs because air flows through the air spaces in the material. The bottom of the rock layer is cooler than the top., They're not moose tracks , They are a portion of the snow layer just at the top of the rock shoulder. Air flows upward and out of the upper surface, creating vent holes along the edge of the road. During winter, these holes can be seen in the snow along the shoulder of the roadway. On cold days, moist air can be seen exiting these holes in the form of vapor clouds., One of the vent holes , The bright orange in the center indicates that the vent hole is much warmer than the surrounding snow surface. The air is warmed as it circulates through the rock layer and exits at a much higher temperature than it entered. One hundred temperature sensors are buried in the embankment to monitor the cooling effect of the air convection embankments., Engineering the road , Design and construction of the Thompson Drive entrance to the UAF campus were a collaborative effort between the Alaska Department of Transportation and Public Facilities and engineering faculty at the UAF College of Engineering and Mines and the UAF Institute of Northern Engineering. The institute focuses on studying engineering challenges unique to the circumpolar North.