It is an unusual sight to behold: Freight trains zipping through Europe, across country borders - and over myriad rail voltages and national train systems.

• 这样的情形可不一般：货运列车在欧洲大陆蜿蜒前行，越过一道道国境线，自由地穿越在众多电压等级和各国的铁路系统之间。