World Download Available Here
(The download included in this project is the design world)

Update 31.12.17: Added a new connection to my latest build among other small things.

What is this thing?
As you (maybe) know, if you travel 1 block in the Nether you've traveled 8 blocks in the Overworld, meaning that it's very useful to use the Nether for traveling long distances in the Overworld. The Nexus takes full advantage of that; It's a massive rapid transit system in the Nether that connects my base to every other significant place in my world by rail, which makes it very easy to quickly travel to these even if they're thousands of blocks away. Also, this is where you spawn when you download my world, so you can immediately travel to whatever specific project you want to see for yourself - read page 2 of the book in your hand for instructions, it's easy!

How does it work?
The heart of the system is the hub area, from where we can select our desired destination. There are up to 16 destinations possible for each direction (15 selectable + 1 if you don't select anything) which makes a total of up to 64 possible destinations. Unlike my previous attempt at a network like this which had everything connected directly by redstone, this one works a little bit different.

As I explain in the video, when you select a destination a dropper dispenses an item onto a Minecart track which then gets picked up by a hopper minecart. The hopper minecart then waits until the player is in the Minecart and presses the button start the process. Warning: You have to wait until the note block has played before pressing that button because that hopper minecart MUST be in front of you! If you've messed up and selected the wrong station, no worries. I added reset button as well.

The Minecart with the player travels over a detector rail which releases the hopper minecart just in front of it. The track switches basically work by a simple storage array: If the item in the hopper minecart is the same as the item in the hopper, the signal is extended which activates a hopper clock. This, in turn, is what activates the track switch just long enough for both carts to pass through. If the item in the hopper minecart isn't the same then the track switch won't be activated and both carts travel on until it is.

Before each station, an empty cart detector detects the hopper minecart and puts in a separate holding area. The stations have some control too, they have a dispenser for Minecarts and a button to return the hopper minecart back to the hub manually (useful if you don't return to the station). Each station also has an empty cart detector for the player minecart because empty minecarts (other than the hopper cart) cannot enter the system otherwise it'll break for obvious reasons.

For the return journey, a detector rail this time activates all the track switches you pass through. Before the return to the hub, another empty cart detector separates the carts again, just like the stations.

The build
Man, this thing took a long time. Building in the Nether is always a pain, just add the monstrosity of this thing to it and BAM. For the hub, I went with a nether-portal like look, like my previous hub, but this time I used black clay and purple carpet. Under the carpet, I hid jack-o's for lightning.

I had to do a lot of terraforming as well and make sure ghasts won't blow it to bits, especially around the Minecart tunnels and stations. I went with the same tunnel design as with my previous hub, but instead of using quartz and nether brick I just used block stone and stone slabs this time.