One of the distinctive characteristics of Indian Railways is its track gauge.
Indian Broad Gauge measures 1,676 millimetres, equivalent to 5 feet 6 inches, between the running faces of the rails.
By comparison, the standard gauge widely used internationally measures 1,435 millimetres.
Broad gauge is now the dominant gauge on Indian Railways, with many former metre-gauge and narrow-gauge routes having been converted to it.
The wider gauge supports large passenger coaches, powerful locomotives and heavy freight operations and has become the foundation of India's main railway network.