Heya Tilt
Trains are country owned. They just go around their little track. I add a station or two for each line. Name the line something... ie: "northeast train" Place your train. In the pulldown menu select which track the train is assigned.
Add a depot near the train track but a few miles from either a field, or strat group.
Add road from depot to strat/field. In the properties window, click "start from" put the depot number here "go's to" put the field number. In the case your road services a strat group, use the pull down menu and select which type strat.
Add convoy on road. Trucks are field owned. (usually the depot number, but it doesn't have to be) Now select "change all" On the top select "convoy" hit change.. bottom the track name. (double check all 8 trucks are on the correct track and listed as convoy)
Remember to make discriptive names for all tracks so you don't get confused. The end of the day you have 50 or 60 tracks.
Notes: For roads If you don't add points on track back to starting point, the truck when they reach the end of the line, will dissapear and start at the beginning.
Hope this helps