Brief synthesisThe Mountain Railway of India consists of three railways: the Darjeeling Himalayan Railway located in the foothills of the Himalayas in West Bengal (Northeast India) having an area of 5.34 ha., the Nilgiri Mountain Railways located in the Nilgiri Hills of Tamil Nadu (South India) having an area of 4.59 ha. The Mountain Railways of India are outstanding examples of hill railways. The Mountain Railways of India are outstanding examples of a technological ensemble, representing different phases of the development in high mountain areas. The Mountain Railways of India are outstanding examples of how access has been provided to the plains and plateaus of the Indian mountains. Indian Railways has a central research department that considers climatic and geological effects with an impact on mountain lines (RDSO).