This is my first post so hang with me if this has already come up in conversation.
I'd like to think there is more to the train tracks and what they mean for this half of season 4. After seeing Terminus appear on signs I did a search on the internet to see if the name related to a particular monument or place. Terminus, from what I found, is an area in Atlanta where railways ended that were connected to cities in the Midwest.
I believe Terminus will be a train station that takes any survivors to the actual Sanctuary in D.C.. I think one of the last scenes we will see is the prison group getting on a train or traveling on a train together.