So far in this thread, I have seen at least two different definitions of "railroading".
To me, railroading is when the GM makes things happen to the PCs or forces the PCs to do something against their will and/or with no choice.
For example, take the door to another dimension mentioned earlier. Say one PC has a spell that allows him to see the most probable outcome of opening the door. Given that knowledge, the PCs decide to leave the door alone.
Now, if the GM has the door just pop open and suck them in - to me that is railroading, or if the spell gives the PC the wrong information (without a plausible reason for doing so), then that is railroading.
In short, railroading, to me, is when the GM forces events upon PCs without allowing the PCs a choice or a chance to avoid/counter/overcome such events solely for the purpose of advancing his (the GM's) plotlines.
However, the example given about the fork in the road, and the GM situating the encounter on whichever fork the player's take, is not railroad, it is just being a flexible GM, adapting his plotlines to the actions of the players.
If he forced the players to go after the kidnapped girl without giving them the choice, that would be railroading. But in the situation he set up, he is just being flexible in providing them with the opportunity to have the choice of whether or not they help the caravan or rescue the girl.
THe difference can be a very thin line sometimes, but there is a difference. Railroading is forcing the players to stick to the plotline developed, being a flexible GM is adapting the plotline (and encounters, etc..) to the actions of the PCs.
At least that is the way that I see it...
