Some time later...

Ok, have spent a happy couple of hours surfing away, looking for the work of Isotype, Marie and Otto Neurath, and Gerd Arntz. They were all variously involved in producing graphics like this:


They often used that "small repeater" convention, where an individual symbol does not get larger to indicate a greater quantity but, instead, multiples of the symbol are printed -- here's the other option (each wagon is proportionate in size to the amount of capital invested in building the systems, and to the quantity of freight and passengers):


The Isotype solution would have had strings of trains, one for each country, each printed above the other, the number of wagons behind each representing the quantities.

Here's something similar -- length of track illustrates, er, length of track:


Well I think they're delightful, anyway...