Boston Sprinter Safety Systems Guide?

Discussion in 'PC Discussion' started by aglomarsale, Aug 23, 2021.

  1. aglomarsale

    aglomarsale Well-Known Member

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    I cannot find it, after 30 mins. Can anyone please post it for my convinience? Thank you.
    (ATC, ACES)
     
  2. redrev1917

    redrev1917 Well-Known Member

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    its not been released yet which is why you cant find it.

    Main advice to give you is once the in cab signal gives you a reduced speed limit, put the throttle to neutral, brakes in to suppression and hit the alerter button, once you are below the new speed limit you can take of the breaks and apply throttle again.
     
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  3. aglomarsale

    aglomarsale Well-Known Member

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    Oh ok, Thank you so much. Last time when it gave me a warning, I just pyt the brakes into around 30% braking, and waited. Eventually it would get mad at me and apply emergency brakes even after I spam the acknowledge button.
     
  4. Jinoss17

    Jinoss17 Well-Known Member

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    DTG:

    [​IMG]
     
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  5. aglomarsale

    aglomarsale Well-Known Member

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    But when I put the brakes into supression, the train seems to slow down at a slightly unrealistic rate, like a car instead of a train. Is it like that in real life, where the train applies its brakes very hard? The passengers might find it uncomfortable lol
     
  6. aglomarsale

    aglomarsale Well-Known Member

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    LOL thank you for making my day :) :)
     
  7. redrev1917

    redrev1917 Well-Known Member

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    thats prototypical for the NEC and if youve ever riden it yes you will find it uncomfortable at times.
     
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  8. aglomarsale

    aglomarsale Well-Known Member

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    Ah right. unusual, yet very interesting. Thank you
     
  9. Stephen Crofts

    Stephen Crofts Well-Known Member

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    I’ve also been caught out with not enough braking. It wants the suppression setting within a certain time it seems and nothing else. on a controller it’s easy to fly past suppression, it really needs a sticky notch to avoid going beyond it.
     
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  10. aglomarsale

    aglomarsale Well-Known Member

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    Also, in the MBTA trains, supression is the MAX brake setting, just a notch above full brakes. IRL, do the engineers really put supression braking, even if its the highest brake setting?? On the ACS64, at least its 64% but in the MBTA..? If I was a passenger I would probably puke
     
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  11. breblimator

    breblimator Well-Known Member

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  12. cActUsjUiCe

    cActUsjUiCe Developer

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    I posted a quick little blurb in the TSC Discord last night. Not the comprehensive guide I plan on making soon, but it should help for right now.

    ATC = Automatic Train Control. It's a system that displays the current block conditions in the form of a cab signal. The cab signal displayed conforms to the wayside signals that you pass along the way. So if you pass a signal displaying Clear, the cab signals will display Clear. You can read the NORAC Operating Rules to see conformity between fixed signals and cab signals.

    When cab signals downgrade to a more restrictive aspect (i.e. Clear to Approach Medium 45), you must put the brakes into the suppression notch and acknowledge the downgrade is cab signal aspect. When the train's speed is at or below the signal speed, you can then release the brakes.

    Keep in mind that ATC only enforces signal speeds. For example, 125MPH for Clear 125, 45MPH for Approach Medium 45, and 30MPH for Approach. There are more, but I'm not listing them all.

    ACSES = Advanced Civil Speed Enforcement System. It provides the ability to enforce permanent speed restrictions, temporary speed restrictions, and can also enforce positive stop at interlocking home signals.

    A permanent speed restriction is the maximum speed allowed on a section of track. For instance, a 130MPH curve. ACSES can ensure that you don't exceed 130MPH when going around that particular curve. But how does it do this?

    ACSES is a distance-based system. As the train passes over transponder sets in the tracks, information is sent to the train's on-board ACSES computer. This computer receives the data and determines a maximum authorized speed. There's a bunch of other information sent by the transponders to the computer, but that's not relevant now.

    Part of the calculation is a braking curve for upcoming restrictions. There's two curves that get calculated: a braking curve and an alert curve. The braking curve is the latest that you can start braking and still meet the requirements of the upcoming restriction. The alert curve is the braking curve with an 8 second offset. So take the following example from the Boston to Providence route. You're going 125MPH around South Attleboro and there's a 60MPH restriction ahead (the curve at milepost 190.4).

    How does the train enforce 60MPH at the curve?
    If you exceed the calculated speed of the alert curve, the 60MPH restriction immediately appears on the ADU. You must (within 8 seconds) apply permanent suppression braking and acknowledge the alarm. Once at 60MPH or below, you can release the brakes and continue on your way.

    If you brake really early and never exceed the alert curve, you'll continue to see a maximum authorized speed of 125MPH on the ADU until you actually reach the curve. At which point you'll see 60MPH appear on the ADU. This reduces engineer reliance on the system and encourages them to memorize speed limits (as they should).

    If you exceed the braking curve, then the system will automatically brake the train for you. You can not release the brakes until the train's speed is at or below the target speed of the upcoming restriction. Doing a brake release like this is called a "running release".

    The final function of ACSES is Positive Stop. At applicable interlockings, it'll enforce absolute Stop aspects. Meaning if a home signal at an interlocking is displaying a Stop aspect, the ACSES on-board computer will ensure the train comes to a complete stop several hundred feet in advance of the interlocking.

    How does it know that the interlocking home signal is displaying Stop? Data radios.

    It took a while, but Amtrak finally secured a dedicated radio frequency for interlocking equipment to transmit interlocking states to the ACSES on-board computer of trains in the vicinity. Once the train is close enough to the interlocking, the equipment there will send a bunch of different information to the train's ACSES computer via radio frequency. This computer will then calculate a dedicated braking curve that'll ensure a positive stop in advance of the home signal.

    It's only during ACSES Positive Stop that the ADU will display the "time to penalty". The time to penalty denotes how long the engineer has to come to a complete stop before the train will intervene.

    Once the train comes to a complete stop, the ADU will actually display "STOP SIGNAL" with a signal speed of 0mph. The engineer cannot override this without dispatcher permission.
     
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  13. cActUsjUiCe

    cActUsjUiCe Developer

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    Here are a couple positive train stop graphics to explain the concept.
    unknown.png unknown2.png
     
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  14. bescot

    bescot Well-Known Member

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    A couple of questions to those who might know better.

    Eg. Approaching Providence: You're brought in on 3x yellow approach aspects after one another with nothing in front, so are limited to 30 by ATC for all that distance. Why?

    The signal before the station stop is medium approach red/flashing yellow. Still 30. The next signal just off the end of the platform is stop. The ACSES enforces restricted as you enter the platform, and before the stopping point says STOP. How do you do the station stop when the train isn't position ed fully in the platform?.
     
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  15. cActUsjUiCe

    cActUsjUiCe Developer

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    Instruction at Providence doesn't have "dispatch beyond instruction" checked, so the signal at the end of the platform will be a Stop signal. The signal progression leading you to that stop is currently bugged and not working as intended.

    In real life, the ACSES positive stop distance for home signals close to platforms is intentionally set to lower values so that you can make the station stop without issue. This functionality isn't programmed into the game. It's something I will request gets added. Should be very simple to implement.
     
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  16. bescot

    bescot Well-Known Member

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    Thanks so much Brandon. I really do appreciate your work on the route, and your community engagement.

    Have you seen if the dispatch beyond instruction is set at Hyde Park track 3? The southbound approach for trains which stop there is painfully slow. The signal is 900yds beyond, and you're forced to 30mph over 4 signal blocks: approach limited > medium approach > medium clear and then 20mph approaching Hyde Park for the stop signal beyond. ATC steps back up to 30 when you close the doors.
     
  17. cActUsjUiCe

    cActUsjUiCe Developer

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    It's per instruction, not per signal. So I need to know the service you're operating in order to check. But I suspect it's not checked.
     
  18. bescot

    bescot Well-Known Member

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    Franklin 745, but I've seen it on every Boston - Readville train I've driven
     
    Last edited: Aug 24, 2021

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