In the past, modellers would interchange freight cars with each other via USPS. But there are two problems with this: $$ and the need to make arrangements with the receipiant.
Is the 21st century of interchange Geocaching? Geocaching is a hi-tech treasure hunt were the players can move trackable items called “Travel Bugs” across the country. (see: http://www.geocaching.com)
If a freight car were to have a “Travel Bug Tag” attached to it and released into the wild, it would face the same hazards that a real freight car would face in interchange service - it would depend on other people to move it, you would have an accounting of the actual miles that it has travelled when it reaches a destination, and the car also face the risk of damage or destruction in transit.
The one difference is that there is not a fixed destination for the car.
I have done just this with a cheap freight car to test out the above concept. You can track this car’s progress by visiting:
http://www.geocaching.com/track/details.aspx?tracker=TBGX30
If there is interest, I can expand on this concept and a couple of twists on this idea.
Later…