Try to analyze from a natural point of view (topography, climate, rivers, etc.). ) Why is it so difficult to build a service road?

(1) Take up cultivated land as little as possible. Cultivated land resources in the world are very scarce and non-renewable.

(2) Try to avoid passing through wetlands, rapids and wide water surfaces. Because the cost of building bridges, culverts and waterproof subgrade is high.

(3) Avoid steep slopes as much as possible. When the vehicle climbs a steep slope, the engine runs at full load, which not only wastes fuel, but also accelerates mechanical wear. Therefore, the dangerous terrain should be built into Panshan Road.

Climate:

(1) When building roads in the south of the Yangtze River, it is necessary to consider the soaking of subgrade by rain in rainy season. Excessive moisture will reduce the strength of subgrade.

(2) When building roads in desertification areas and Gobi desert, pavement weathering caused by dust should be considered. Some areas are still plagued by quicksand, and moving sand dunes will bury several kilometers of roads.

(3) Northeast China, Xinjiang, Tibet and other regions have severe cold weather. Under the action of thermal expansion and cold contraction at low temperature, great stress will be generated in subgrade masonry, and even cracking will occur. This must be prevented.