Permafrost degradation illustration (IMAGE) University of Alaska Fairbanks Caption This diagram models half a road in cross-section from the road center to the adjacent tundra. The graphic illustrates the subdivision into four structural units (road center, shoulder, toe and tundra). The grayish area with black dots represents the road embankment. The light blue shading indicates potential maximum snow height. The dark blue area illustrates ponding next to the road. Credit Image distributed under Creative Commons 4.0 International Usage Restrictions Creative Commons 4.0 International License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.