-------------------------------------------------------------------
| LGB Yard Configuration 1  (aka: Blocking)                         |
 -------------------------------------------------------------------
              ________(5)________                          ________(PS2)________
       __(1)_/________(4)________\_(2)_            __(YS)_/________(PS1)________\_(LS1)_
     /                                  \        /                                       \
    |                                    |      |                                         |
    |                                    |      |                                         |
    |                                    |      |                                         |
     \___(3)____________________________/        \___(LS2)_______________________________/

    Points:
        1) Yard switch (YS)
        2) Light sensor (LS1), immediately after yard
        3) Light sensor (LS2), offset closer to end of mainline
        4) Powered section 1 (PS1)
        5) Powered section 2 (PS2)

    Beginning State:
        1) PS1 and PS2 depowered.
        2) Train 1 (T1) on PS1.
        3) Train 2 (T2) on PS2.
        2) YS default to open (right).

    Operation Cycle:
        1) Power PS1.  [T1 moves from siding to mainline]
        2) T1 moves over LS1.
        3) Depower all segments. [PS1 is depowered]
        4) T1 moves over LS2.
        3) Power PS2 [T2 begins to move], close YS to send trains into siding.
        4) T2 begins to move.
        5) T2 moves over LS1.
        6) Depower all segments [PS2 is depowered]
        5) Both Train A and Train B are moving on mainline.
        6) T1 approaches YS (closed), and is sent into siding.
        7) T2 moves over LS2.
        ...




 -------------------------------------------------------------------
| LGB Yard Configuration 2 (aka: Block/Passing)                     |
 -------------------------------------------------------------------
              ________(6)_______                                   ________(PS2)_______
       __(1)_/________(5)_______\___(3)_                  __(YS1)_/________(PS1)_______\___(LS1)_
     /     (2) \______(7)________/       \              /     (YS2) \______(PS3)________/         \
    |                                     |            |                                           |
    |                                     |            |                                           |
    |                                     |            |                                           |
     \___(4)_____________________________/              \___(LS2)_________________________________/



    Points:
        1) Yard siding switch (YS1)
        2) Yard secondary siding switch (YS2)
        3) Light sensor (LS1), immediately after yard
        4) Light sensor (LS2), offset closer to end of mainline
        5) Powered section 1 (PS1)
        6) Powered section 2 (PS2)
        7) Powered section 2 (PS3)

    Beginning State:
        1) PS1, PS2, PS3 depowered.
        2) Train 1 (T1) on PS1.
        3) Train 2 (T2) on PS2.
        4) Train 3 (T3) on PS3.
        5) YS1 default to open (right).
        6) YS2 default to open (left).

    Operation Cycle:
        1) Power PS1.  [T1 moves from yard to mainline]
        2) T1 moves over LS1.
        3) Depower all segments. [PS1 is depowered]
        4) T1 moves over LS2.
        5) Power PS2 [T2 begins to move, T1 is already in motion], set switches to send
           to PS2 (YS1 closed, disregard YS2).
        7) T2 moves over LS1.
        8) Depower all segments. [PS2 is depowered]
        10) T1 approaches YS1 (closed), and is sent PS2.
        11) T2 moves over LS2.
        12) Power PS3 [T3 begins to move, T2 is already in motion], set switches to send
            to PS3 (YS1 opens, YS2 closes)
        13) T3 moves over LS1.
        14) Depower all segments. [PS3 is depowered]
        15) T2 approaches YS1 (open), YS2 (closed), and is sent into PS3.
        16) T3 moves over LS2.
        17) Power PS2 []
        ...
        @TODO:  OK, so in a block/passing maneuver like this, this really is entirely dependent
                upon where the trains are, as opposed to the powered sections.  It's not a
                PS1, PS2, PS3, PS1, PS2, ... as much as a T1, T2, T3, T1, T2, ... system.
                Shouldn't be hard to figure this out, can probably do so on init, take the number
                of powered sections and plan the "power map" for automated control.




 -------------------------------------------------------------------
| LGB Yard Configuration 3 (aka: The WTF Mate)                      |
 -------------------------------------------------------------------

       ________________________________________
     /                                         \
    |            ________(9)_______             |
    |     __(1)_/________(7)_______\___(4)_     |
    |   /     (2) \______(8)________/       \   |
    | |                                     |   |
    | | (3)                                 |   |
     \|                                     |   | (6) [necessary? only if it shall be complicated]
       \___(5)_____________________________/    |
                                 \_____________/


    Points:
        1) Yard siding switch (YS1)
        2) Yard secondary siding switch (YS2)
        3) Local switch (YS3)
        4) Light sensor (LS1), immediately after yard
        5) Light sensor (LS2), offset closer to end of mainline
        6) Light sensor (LS3), offset near the end of the country (non-local) route
        7) Powered section 1 (PS1)
        8) Powered section 2 (PS2)
        9) Powered section 2 (PS3)

    Goal:
        1) Control similar to the block/passing setup as before, except intermittently send a
           train around the country, skipping their planned stop in the local yard




 -------------------------------------------------------------------
| Fundamental Train Yard Operations                                 |
 -------------------------------------------------------------------


    Fundamental operations:
        - Cycles.
            - Begins when a train rolls out, through the point it rolls onto LS2 (the last
              switch, indicating a train ready for return to the yard)
            - In each cycle, there is a "current section" which is, generally the section
              that currently has power or the section the last train departed from
        - LS1 rollover operation
            - Depower the "current section" from previous cycle
            - Determine and set next "current section"
                - For two yard sections: 1, 2, 2, 1, 1, 2, ...
                - For three yard sections: 1, 2, 3, 2, 3, 1, 3, 1, 2, 1, 2, 3, ...
        - LS2 rollover operation
            - End current cycle.
            - Set switches to reflect "current section"
            - Power the "current secton"




 -------------------------------------------------------------------
| LGB Parts Analysis, for parts needed                              |
 -------------------------------------------------------------------

    Atlas Selector:
        - 4 SPDT switches, comm power, one hot, one dead

    LGB Switch:
        - 4 DC DPDT switches.  No clue how they really work yet.  Reversed power, maybe?
          Diagram bookmarked.