New rail system proposal for 1.5

We on the slavislands have some nice ideas about the railwork automation with upcoming 1.5 tools and since the nether is probably going to be reset that things might come in handy for the whole server.

Manual track selection sucks. There are numerous on-the-rail track selection solutions but some people vouched for a complete lay-back system when you would only select a destionation once when getting inside the minecart. The core idea is to make use of analog properties of a redstone signal and use the signal strength as a code for the required destination or hub. The signal would travel along under the rail and direct the switch to a corresponding rail.

1. The user must be able to select a destination once.
2. There should be a single rail, or 2 rails for opposite directions max.
3. Optionally the user should have a manual intervention control should he change his mind.
4. The system should be able to serve multiple users at once.
5. The system should not malfunction because of misuse (e.g. riding in opposite direction).

1. Redstone signal may have 15 states, therefore a maximum of 15 stations can be served at one hub. Special signal codes may be reserved for long interhub rails though, but the careful placement of hubs is still critical.
2. To avoid cart clashes the system would naturally require 2 rails for the opposite directions. This can be worked around somehow, but the underlying powerline still has to be doubled because of comparator's polarity.
3. The signal must travel through a line of comparators which eat up a lot of redstone and quartz. One can place 1 comparator every two blocks but given 2 lines requirement it would still require ⅔ comparator-equivalent for every block traveled.
4. The signal travels a lot faster than a minecart does, therefore the signal must be “caught” at several regular points along the way allowing the cart to catch up.

1. Economic nonfading signal line (WIP, current record ⅓ comparator per block)
2. Signal catching trap (DONE, needs a reset mechanic)
3. Destination selector (TRIVIAL)
4. Automatized switch (WIP)
5. Manual emergency control of automatized switch (TODO)
6. Cart redirector to prevent driving on a wrong lane (TODO)
7. Statistical analysis on the frequency of redirectors and signal traps (TODO)
8. Blueprints (TODO)