The ideal alignment of a railway line should meet the following requirements.
Purpose of the New Railway Line
The alignment of a new railway line should serve the basic purpose for which the railway line is being constructed. As brought out earlier, the purpose may include strategic considerations, political considerations, developing of backward areas, connecting new trade centres, and shortening existing rail lines.
The new railway line should fit in with the general planning and form a part of the integrated development of the country.
The construction of the railway line should be as economical as possible. The following aspects require special attention.
Shortest route It is desirable to have the shortest and most direct route between the connecting points. The shorter the length of the railway line, the lower the cost of its construction, maintenance, and operation. There can, however, be other practical considerations that can lead to deviation from the shortest route.
Construction and maintenance cost The alignment of the line should be so chosen that the construction cost is minimum. This can be achieved by a balanced cut and fill of earthwork, minimizing rock cutting and drainage crossings by locating the alignment on watershed lines, and such other technical considerations. Maintenance costs can be reduced by avoiding steep gradients and sharp curves, which cause heavy wear and tear of rails and rolling stock.
Minimum operational expenses The alignment should be such that the operational or transportation expenses are minimum. This can be done by maximizing the haulage of goods with the given power of the locomotive and traction mix. This can he achieved by providing easy gradients, avoiding sharp curves, and adopting a direct route.
Maximum Safety and Comfort
The alignment should be such that it provides maximum safety and comfort to the travelling public. This can be achieved by designing curves with proper transition lengths, providing vertical curves for gradients, and incorporating other such technical features.
While deciding the alignment, aesthetic aspects should also be given due weightage. A journey by rail should be visually pleasing. This can be done by avoiding views of borrow pits and passing the alignment through natural and beautiful surroundings with scenic beauty.