Traffic Condition:
If the track experiences high traffic intensity, a gauge wider than the standard gauge may be more suitable.
Development of Poor Areas:
Narrow gauges are often laid in certain regions to facilitate the development of economically disadvantaged areas, connecting them with the more developed world.
Cost of Track:
The cost of constructing railway tracks is directly proportional to the gauge width.
When available funds are limited, opting for a meter gauge or a narrow gauge is preferable to having no railways at all.
Speed of Movement:
The speed of a train is influenced by the diameter of the wheel, which, in turn, is limited by the gauge.
The wheel diameter is typically about 0.75 times the gauge width, making the speed of a train nearly proportional to the gauge.
For higher speeds, a broad gauge (B.G) track is preferred over meter gauge (M.G) or narrow gauge (N.G) track.
Nature of Country:
In mountainous terrain, it is advisable to use a narrow gauge track due to its flexibility and ability to be laid on smaller curves.
This explains why some significant railways, spanning thousands of kilometers, are constructed with a narrow gauge as small as 610 mm.