SIGNALING AND BLOCK PARTITIONING

 

SIGNAL LOCATION AND ORIENTATION

LAYOUT BLOCK PARTITIONING

METHODOLOGY: SUMMARY

 

 

Once the layout has been sketched, and before being able to run simulations, it's now time for setting signals.
This operation aims at partitioning the layout into as many blocks as necessary, according to the traffic
(number of trains) you wish to achieve.

* Click on images for zoom *

 

SIGNAL LOCATION AND ORIENTATION
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The signal symbols are used for setting layout block boundaries, and protect all turnout areas.

Hints for correct signal location and orientation:

  • The origin of the signal is the base of the thin vertical line.

  • With the radio buttons, in the left hand side capture menu, or with the keyboard space bar, the proper
    signal location and orientation is selected, towards the turnout(s) to be protected.

  • It is highly recommended to leave a safety distance, between the protecting signal, and the turnout end.
    As a rule, the recommended length for this safety area is one loco length: that is approximately
    20 cm for HO scale, and 12 cm for N scale.
    This "rule of thumb" avoids (if the layout is to be software driven), that a loco assigned to stop ahead of
    the signal, could straddle over the turnout, due to a bad speed calibration, for instance.
    It also ensures that, as long as a loco stays on the turnout, or is stuck on it (due to bad contacts), no other
    train will be able to access this turnout.

 

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LAYOUT BLOCK PARTITIONING
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To make it simple, for a first simulation approach, let's admit that a block is a track section bounded by two
signals in opposite directions.

  • This track section must be longer than the longest consist which may travel on it.

 

 

  • If a track section is too short to be used as a block, then it must be lumped with the surrounding turnouts,
    into a "turnout area".

 

 

  • Conversely, if a track section is long enough, it is possible to subdivide it into several blocks.
    These blocks are separated by two signals, in opposite directions, and at the same location (block boundary).
    The bases of these two signals must be exactly at the same place.
    IMPORTANT NOTE: if the track section is 2-way (that is trains may travel on it in both directions), then this
    subdivision into several block is NOT recommended, since it may lead to blocking situations, between two
    trains in opposite direction.
    On the other hand, if this section is one-way, then it is advisable to create as many blocks as possible, in order
    to increase the traffic capability.

 

 

  • On sidings , the block is bounded by a signal only on the turnout side.
    On the other side, the other block boundary is implicitely defined by the junction of the buffer stop segment.

    NOTE 1: The block limit on the buffer stop side is the junction of the buffer stop, NOT the red bar of the
    buffer stop. In other words, the buffer stop segment length is only for "scenery"; it is not functional.

    NOTE 2: The signal to be used ahead of the siding turnout is the 2 state signal.

 

 

IMPORTANT HINTS:

  • If, after the first simulation runs, you wish to move or modify signals, it won't be possible (on current
    CDM-Rail version) unless you remove routes and simulation contexts using those signals, including
    contexts automatically generated by CDM-Rail ( _SIMU_CTXT et _RUN_CTXT ).

  • Save your ".lay" as often as possible whenever you modify it.
    A good practice consists of saving it under a different name on any signifcant step of the project.
    For example, the ".lay" name could include the date, or the step name, ...

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METHODOLOGY: SUMMARY
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Here follows the suggested step sequence, for best methodology.

  • First of all , protect all layout turnouts, lumped into "turnout areas", with signals facing the turnout area.
    And keep in mind the safety distance between signals and turnouts.

 

 

  • Then, subdivide all ONE-WAY track sections into as many blocks as possible,
    keeping in mind that any block must be longer than the longest consist bound to travel on it.
    If you add a small safety margin, then you'll make sure that no train will exceed the block boundaries.
    If any track section is too short for holding a block, then it must be merged with surrounding turnouts,
    into a larger "turnout area".

 

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