If you look closely at the major railway routes in South Asia and elsewhere, you will notice fairly large railway facilities at places which were not important towns to begin with. So there must have been some reasons for locating these stations at a particular place.
Sometimes the reasoning was clearly stated. In the earlier days of the East Indian Railway the large workshops and training centres were set up at Jamalpur in Bihar. The EIR administration did say that they did not want the junior employees to be distracted by the bright lights of Calcutta.
Another peculiar station was Barog on the Kalka-Shimla route. This station does not have much population in the vicinity and exists primarily to provide food to the passengers. (Although there is a larger town Solan few km away),
On the micro scale, crossing stations needed to be set up for the convenience of smooth running on single line sections. There are literally hundreds of such stations all over the country. For example, persons familiar with the Haridwar-Dehradun area would know Motichur and Kansrao stations which exist only for crossing purposes.
Junctions would need to be set up where important routes met. Other stations with coaling and watering facilities for steam locos would need to be set up at certain intervals. Sometimes this could be done at the junctions. If not, a large station would have to be set up at a place which was not already a junction. The criteria for location would be that it would be 100-250 km from the nearest station with similar facilities.
We will look at such stations on the trunk routes in subsequent blogposts.