Factors Affecting the Selection of Hill Road Alignment
The various factors which control the alignment of a road in hilly areas. Following are the 8 Factors which affect the selection of hill road alignment:
1. Length Of Road
The cost of construction very much depends on the length of roads in hilly areas. The cost of construction of a hill road for each kilometre length is relatively high. hence, The alignment should be as short as possible so as to make the road project economical.
2. Loss Of Height
The alignment should not lose height.
3. Geometrical Standards
The alignment should have proper geometrical standards such as gradients, curves, sight distance, the radius of the curve etc. It should be free from sharp hairpin bends.
4. Existing Saddle or Pass
The alignment should cross the series of hills through the existing saddle or pass.
5. Drainage line
The alignment should be parallel to the drainage line to avoid the construction of cross-drainage structure.
The alignment should be provided along the side of a hill which is stable & not very steep.
If provide lower altitudes, the large numbers of cross drainage works are required to be constructed. Hence, the alignment should not be provided at very low altitudes so as to avoid large number of cross-drainage works.
8. Cutting Through Rocks
The cutting of rocks is very expensive. As far as possible, The alignment should avoid cutting through solid rocks.