I've saved my game just as a big dwarven caravan entered the map. It entered quite close to my main gate. However, there's something in the path, a dead goblin pehaps, that is scaring one of the merchants and making the whole caravan go away. There are many alternative paths to the trading depot, if the caravan would just choose another route it could reach it with no problem.
However, I don't have a lot of time to build obstacles in the way, or dig/channel/flat the passage preventing their arrival, etc. I also tried to restrict the traffic, but didn't work (probably because the wagon's path was already set). I tried a few times, will keep trying (with burrows, etc), but I'm afraid I won't be able to create an obstacle in time. Is there any other way to persuade the caravan to change path in a short notice? Without making it give up and go away from the map?