Here is another video i put up about making a portal connect to Close by portals in the over world making it possible for local travel without worrying about the portal system linking you to the wrong spot, this is an idea that etho has been working on in his lets play and i had thought about before and seeing his eppisode prompted me to have a go, this design is expandable and it designed to be used in large bases where travel without physical means is desirable.
Enjoy let me know what you think!
Thanks for any help you can offer.
I didn't find the right solution from the internet.