Indian Railways: Divided By Zones, United By Railfans - Karthik

Does track gauge vary from country to country?
To avoid being invaded by enemies during wartime, some countries decided to install railway systems
with track gauges that differed from those of their neighbours.
As a result, track gauges vary considerably from one country to the next.
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1825, George Stephenson, inventor of the first passenger train, chose a track gauge of 4 feet 8½ inches, or 1,435 mm. While this spacing between the rails has become the norm in many countries, it has since been modified in some areas for military reasons, making it too expensive to standardise the railway systems again. Thus, track gauges across the world vary considerably: 1,000 mm in South America and parts of Africa, 1,067 mm in southern Africa, 1,520 mm in Russia and Eastern Europe, 1,668 mm in Spain and Ireland…
By ALSTOM