NTES is the salt of Railfanning. IRI is the sugar. - Kirti Solanki

Ex:- 1) click here Japanese dual guage tracks and guage changing trains..
such technique is used in Spain as well just search for talgo variable guage train on Google..you will get your answer .

Ex:-2) BG and SG dual guage tracks in Australia. In Victoria, there are sections of 5 ft 3 in (1,600 mm) and 4 ft 8+1⁄2 in (1,435 mm) dual...
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gauge track between Southern Cross station and West Footscray, Sunshine and Newport, Albion and Jacana, North Geelong and Gheringhap, Maryborough and Dunolly, and in various goods yards and industrial sidings. Until 2008, there was dual gauge line between Wodonga and Bandiana.

At Albury railway station, New South Wales there was 5 ft 3 in (1,600 mm) and 4 ft 8+1⁄2 in (1,435 mm) dual gauge line until 2011.
click here
3) guage changing train in China
click here

Where there is a will there is a way...The nations which have innovative minds prosper and those which go by the already set rules dont..don't just ridicule someone without digging deep into the matter..