[stefanv]

That's more or less how railroads work. Railcars from different sources and to different destinations are added to and removed from trains as they make their way across the country. The only disadvantage with trains is that removing a car from the middle is time consuming. The big advantage with trains is that there's usually only one engine, albeit a much more powerful one. I'm sure the fuel efficiency of trains is much better per kg of useful load than a platoon of trucks, even taking into account that a fleet of smaller trucks is still needed to get things from the train stations to their final destinations.