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Thread: American safety systems modeling

  1. #1
    Join Date
    Nov 2011
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    California, USA
    Posts
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    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:


  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.

  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.

  7. #7

    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.)

  8. #8
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    Location
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    Default

    I see. Again, I do appreciate your expertise, and I'm not trying to "defend" my interpretation of the PRR's system - like you, I'd like it modeled as accurately as possible, and if someone could point me toward some definitive sources, I would be happy to revise my code.

    What I'm confused about is your blanket statement, "Cab signals are not, and were never intended to be, the engineer's memory." It's my understanding that this is more or less how Amtrak's cab signals on the Northeast Corridor work, which themselves are descended from those of the PRR: Your cab signal reflects the state of the block you're currently in. You can see this behavior if you drive the Northeast Corridor in either of Dovetail's train simulators.

  9. #9

    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!"

  10. #10

    Default

    I meant that when I was working on the NECIP (reviewing shop drawings) we were repeatedly reminded that the cab signals were there so that the signal indications would always be visible to the engineer even if a blizzard or a blinding rain obscured the signal heads.

    Also remember that the signals protecting the block that your train is currently in should always indicate "stop".

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