Often, freight forwarders will report: The train is waiting at the port for reloading. So, what does this "reloading" refer to? And why is it necessary to "reload"? This needs to be explained from the differences in "rail gauge" among different countries. The International Railway Association stipulated in 1937 that a rail gauge of 1435mm was to be the international standard gauge. Rails with a gauge larger than 1435mm are called broad-gauge rails, while those with a gauge smaller than 1435mm are called narrow-gauge rails. 

Let's take the China-Europe freight trains departing from China via the Alashankou border as an example. The entire journey requires at least two track changes: The first one occurs at the Dostyk station on the border between China and Kazakhstan, where the train is lifted from the standard track in China onto the broad track in Kazakhstan. The second change takes place at the Brest station on the border between Poland and Belarus, where the train is lifted from the broad track in Belarus onto the standard track in Poland to enter the Malaševich station within the European territory.