Top 4 affected factors which controls the road alignment

                   Factors  Controlling Alignment

The various factors which control the highway alignment in general are: 

Obligatory points

These are the control points governing the highway alignment. These points are classified into two categories. Points through which it should which it should pass and points through which it should not pass. Some of the examples are:

·       Bridge site:- The bridge can be located only where the river has a straight and permanent path and also where the abut and pier can be strongly founded. The road approach to the bridge should not be curved and skew crossing should be avoided as possible. Thus to locate a bridge the highway may be changed.

·       Mountain:- While the alignment passes through a mountain, the various alternatives are to either construct a tunnel or go round the hills. The suitability of the alternatives depends on factors like topography, site conditions, and construction and operation cost.

·       Intermediate town:- The alignment may be slightly deviated to connect an intermediate town or village nearby.

·       Religious Places:- These have been protected by the law from being acquired for any purpose. Therefore, these points should be avoided while aligning. Very costly structures. The presence of a lake or pond on the alignment path would also necessitate deviation of the alignment.

Traffic:-

The alignment should suit the traffic requirements. Based on the origin-destination data of the area, the desire lines should be drawn keeping in view the desire lines, traffic flow patterns, etc.

Geometric Design:-

Geometric design factors such as gradient, the radius of the curve, sight distance, etc. also govern the alignment of the highway. To keep the radius of the curve minimum, it may be required to change the alignment. The alignments should be finalized such that the obstructions to visibility do not restrict the minimum requirements of sight distance.

Economics:-

The alignment finalized should be economical. All three costs i.e. construction cost can be decreased much if it is possible to maintain a balance between cutting and filling. Also try to avoid very high embankments and deep cutting as the construction cost will be very higher in these cases.

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