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  1. #1
    Join Date
    Nov 2011
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    California, USA
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    105

    Post American safety systems modeling

    Cross-posted from Elvas Tower:

    Add a whole new layer of depth to your simulation by simulating train safety and cab signaling systems. Find my work on GitHub. You'll need to run the May 15, 2020 or later testing release of Open Rails.

    The following scripts have been released:

    • Santa Fe Automatic Train Stop (Surfliner, Cajon Pass, etc.)
    • Pennsylvania Railroad Cab Signaling System (PRR Eastern Region)


    Video demo:

    Ryan
    US-based railfan and programmer. Author of various timetables and safety scripts for Open Rails.

  2. #2

    Default Incorrect cab signal aspects.

    On the PRR-EAst-v2: Your cab signal aspects are incorrect!
    You are displaying a Rule 292 STOP cab signal where is should be Rule 281 Proceed as displayed on the gantry ahead.

    The cab signal is supposed to show the NEXT signal ahead of the train . . . NOT the signal just passed.
    TIME.

    regards,
    ............Vince ..............
    ...... Author NECv4 .......
    .... LIRR BUILD PHOTOS ....
    .............LIRR VIDEO.............
    ...... Eschew Obsfucation ......

    On the The Statue of Liberty in New York Harbor there is a Tablet. On it is written:
    "Give me your tired, your poor, your huddled masses yearning to breathe free,
    the wretched refuse of your teeming shore, send these, the homeless, tempest-tossed to me,
    I lift my lamp beside the golden door!"

  3. #3

    Default

    Vince is correct. Displaying the aspect of the signal just passed doesn't convey much meaningful information. Real PRR cab signals give the indication of the next signal ahead. Also, not every restrictive aspect causes a penalty application, and not every penalty application results in the train actually stopping.

    Think of it this way - The cab signals are the engineer's eyes during a snowstorm. Cab signals are not, and were never intended to be, the engineer's memory.

    David P. Carleton
    D. Carleton Rail Books

  4. #4
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    Default

    Appreciate the criticism, folks. I don't want to question your expertise, most especially not Vince's, but... every source I've seen suggests the cab signals do indeed enforce the current aspect, not the "next" one as per MSTS style. For example, this TO thread, and this AU thread. Even in the Pennsy's own "Progress on the Rails" video, you can see that the engineer's cab signal does not drop to Approach until he actually passes the signal head.

    Also, the first aspect you see in the video is supposed to be "Restricting," not "Stop" (which the PRR didn't have a pulse code for). The idea is that you upgrade to "Clear" when you pass the first Clear signal.
    Ryan
    US-based railfan and programmer. Author of various timetables and safety scripts for Open Rails.

  5. #5

    Default

    Quote Originally Posted by rman View Post
    (which the PRR didn't have a pulse code for)
    Sure about that? The pulse code for stop was zero pulse per second - the ultimate fail safe device!

  6. #6
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    Default

    Yep. The system could only show four possible aspects:

    • Clear
    • Approach Medium
    • Approach
    • Restricting


    And "Restricting" was the no-code state, sent about 1500 ft before any Stop signals - as modeled by my script. There was no lower "Stop" aspect.
    Ryan
    US-based railfan and programmer. Author of various timetables and safety scripts for Open Rails.

  7. #7

    Default

    Yep. The system could only show four possible aspects:
    Nice quote but the cab signals in the PRR MP54 displayed FIVE aspects, the bottom was the 'no-code' display of stop.

    Ever ridden in the cab of a GG1, an MP54? I have . . .in both.
    My Grandfather was PRR managment and he hooked me up with several cab rides and in a later generation I had rides in the original MU Metroliners and somewhat more recently ( 1980) my daughter and I rodein the cab an AEM7 Washington to NY Penn. 1980 (275).jpg

    In all cases my in cab signal observations were as I stated; "the cab signal displays the oncoming signal NOT the one just passed".

    Think about this for a minute, or maybe you'll need a bit longer longer: Why would you ever want a display of what you just passed.

    regards,

    ps dont rely on wickipedia too much . . . anyone can edit those entries . . . even you!
    ............Vince ..............
    ...... Author NECv4 .......
    .... LIRR BUILD PHOTOS ....
    .............LIRR VIDEO.............
    ...... Eschew Obsfucation ......

    On the The Statue of Liberty in New York Harbor there is a Tablet. On it is written:
    "Give me your tired, your poor, your huddled masses yearning to breathe free,
    the wretched refuse of your teeming shore, send these, the homeless, tempest-tossed to me,
    I lift my lamp beside the golden door!"

  8. #8
    Join Date
    Jun 2013
    Location
    Minnesota
    Posts
    1,400

    Default

    I'm no expert, but my understanding of cab signals is that they tell you the state of the next signal, and is primarily a supplement to (sometimes a replacement of) wayside signals. The cab signal telling you the state of the block you're in would mean it would always show either Stop or Restricting, since the block your train is in will by definition always be occupied. If something happens ahead of you and the signal ahead drops to stop, the cab signal will probably do so, as well (not guaranteed - not all systems continuously updated). A rail break might drop the cab signal, as well, depending on how the pulse code is sent (probably through the rails). But wouldn't the primary warning about the state of the block the train is currently in have come while the train was still in the preceding block, and was still facing the signal protecting said block?

  9. #9
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    Location
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    Default

    I think the correct way to frame this problem is in terms of blocks, not signal heads.

    Code:
       Stop              Approach             Approach               Stop
    (was Clear)           Medium
        o                   o                    o                    o
        |  [===][===][===]  |                    |                    |  [===][===][===]
    ----+-------------------+--------------------+--------------------+------------------->
                Clear          Approach Medium          Approach              Clear
                                                            |---------|
                                                            Restricting
    Cab signals indicate the current state of the block, which can change instantaneously. Signal heads indicate the status of the upcoming block, and regulate movements between blocks.

    This is why cab signals do not show the "next" signal.
    Last edited by rman; 05-17-2020 at 06:46 PM.
    Ryan
    US-based railfan and programmer. Author of various timetables and safety scripts for Open Rails.

  10. #10

    Default

    Oh, okay. Please understand that I have worked on signal systems for a living, on the engineering side of the business, but that was almost 40 years ago. I now work in civil engineering exclusively, and yes, we do have some railroad work.

    That having been said, the information found on Wikipedia will not be consistent with what we learned in school because the methodology now is different than it was then. ("Methodology" meaning we were trying to enforce movement authority but usually not speed limits.)

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