Almost since the first railways were built in that country, the Russians have used a five-foot gauge
… that is, five feet being the space between the two rails. Here in the U.S., and almost everywhere else in the rest of the world, “standard gauge” of 4 feet, 8.5 inches is used. The Russians’ idea, which apparently originated with Tsar Nicholas I, was to create an impediment for any invading armies.
The difference in gauges is something that all trains actually crossing into any part of the former Soviet Union must deal with even today. During a 2011 trip to Europe and Asia, my Berlin-to-Moscow train crossed the border from Poland into Belarus one morning just after dawn and I got to witness the procedure first hand.
A few hundred yards from the border, our train pulled into a long shed and was stopped when we were carefully positioned between heavy jacks, two on each side of every rail car. The wheel assemblies at the end of each car were immediately detached — we call them “trucks” in the U.S.; they’re called “bogies” in Europe -– and each car was jacked up.
The whole process, for a 9-car consist, took less than an hour.