Germany has rail links with the following countries. All are to countries of the same gauge (1435 mm), although electrification (15 kV AC 16.7 Hz) and other systems such as signalling may differ.
Russia and Ukraine use what are known as broad-gauge rails, meaning that the width between a pair of rails is approximately 100 mms wider (1520 mms) than in Europe. Whenever a train from Ukraine crosses into EU territory, goods are moved from broad-gauge to normal-gauge wagons.
In fact, it is known as the “Iberian gauge”. This can be traced back to 1844, when a group of technicians stated that, due to the Spanish and Portuguese orography, the width of the inner sides of the tracks had to be increased.
Finland uses 1524 mm (5') gauge since times when it was a part of the Russian Empire (1809–1917) and does not change it, rolling stock is cross-compatible with very minor limitations (Allegro trains between St.
Japan's topographical features permitted more gradual curves than in Norway, perhaps explaining why the 3'6 gauge was chosen over other even narrower gauges. Edmund Morel (1841–71), a British engineer hired by the Japanese government, conferred with Inoue and it is likely that these two men agreed on 3'6.
Broad gauge of 1,676 mm (5 ft 6 in), commonly known as Indian gauge, is the dominant track gauge in India, Pakistan, Bangladesh, Sri Lanka, Argentina, Chile, and on BART (Bay Area Rapid Transit) in the San Francisco Bay Area. This is the widest gauge in common use anywhere in the world.
Since the chariots were made for or by Imperial Rome they were all alike in the matter of wheel spacing. Thus, we have the answer to the original question. The United States standard railroad gauge of 4 feet, 8.5 inches derives from the original specification for an Imperial Roman army war chariot.