Does routing a caravan just give a one time gold sum or does it create a continuous stream of gold income? If it creates a stream of income, do you get gold evey turn or does it depend on how many turns each return trip takes? Does the caravan stop if I take the destination city over? Is ther any games screens showing trade income? It seems that if its just a one time gold payment that its a waste of time to even bother with it.
It's just a one time thing. If the city is far enough however you can make fairly decent amounts of gold fairly quickly. Ofcourse, it is probably better off in the long run just building things other than caravans, since if you divide the sum of gold you get by the number of turns it took to get there you see that really, you made very little extra gold per turn for all the time it took to make and move that caravan. =P Still, if you're going for an economic victory I suppose you could use them for a little extra cash, provided you had all the buildings you needed and adequate defenses. xD