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(nec: New York) Signals, Atc & Acses And How To Fix Them

Discussion in 'Known Issues & Bug Reports' started by cActUsjUiCe, Mar 21, 2018.

  1. cActUsjUiCe

    cActUsjUiCe Well-Known Member

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    By now I am sure most of you have had a chance to give the new NEC: New York DLC a try. If you have turned on ATC and ACSES, you have definitely struggled with those systems. The good news is that it's not you. These systems are quite bugged. The goal of this post is to explain how these systems should work, how Dovetail Games implemented them, and ultimately how Dovetail Games can fix them.

    HOW THESE SYSTEMS SHOULD WORK
    Let's start with the cab signal system. The top part of the Aspect Display Unit (ADU) displays the signal conditions in the block you are currently occupying, not the conditions ahead of you. As you transition between signal blocks, the ADU will update the cab signal aspect accordingly. So if the signal you just passed is Medium Clear, the ADU will display Approach Medium. The cab signal aspect must conform to fixed wayside signals that you pass. This means you aren't going to pass a Clear signal and have the ADU display Approach Limited. If that does happen, there is a malfunction. Use the below table to see how fixed signals conform to the aspect displayed in the cab. This comes directly from NORAC Rule #552, "Conformity Between Cab Signals and Fixed Signals".

    1.PNG

    Now for Automatic Train Control (ATC). ATC's job is to ensure the engineer complies with speed restrictions associated with signals, and signals only. For example, you currently have an Approach Limited aspect in the cab and you pass an Approach signal. The ADU will change to to Approach (see the table above for how the ADU should conform to the fixed signal you just passed) and ATC will enforce a signal speed of 30MPH. If you are exceeding 30MPH at this time, an audible alarm will sound. ATC will give you 8 seconds to apply the necessary amount of braking and acknowledge the drop in signal aspect. Once these two requirements are met, the alarm will turn off. Once the engineer reaches the signal speed (30MPH in this example), he can release the brakes and continue. It must be understood that ATC only enforces speed restrictions associated with signals, not civil speed limits. That is the job of Advanced Civil Speed Enforcement System (ACSES).

    ACSES is the Positive Train Control (PTC) used on the Northeast Corridor and provides additional layers of safety. The most important feature of ACSES is its ability to enforce civil speed limits. These are the maximum authorized speeds for any particular area. For example, I live next to a 150MPH section of the Northeast Corridor in Rhode Island. Beyond that is a 130MPH curve and then another 150MPH section. These are civil speed limits and ACSES has the ability to enforce these. If a train is on that 150MPH piece of track, ACSES will ensure that the train does not exceed it.

    When the same train is approaching the 130MPH curve, ACSES enforces that by means of braking curves. At all times, the on-board ACSES computer is aware train's speed and the distance to the next restriction. By using this information, it is always calculating a maximum safe braking curve AND an alert curve. The maximum safe braking curve is just that, the absolute latest the train can start braking and still meet the speed requirements of the upcoming restriction. The alert curve is more restrictive than the maximum safe braking curve and it's what the engineer has to follow. When the alert curve has been reached, the numerals in the Maximum Authorized Speed (MAS) section of the ADU will start counting down as the train gets closer to the upcoming restriction.

    5.PNG

    So in the above example, the Maximum Authorized Speed section on the ADU will begin to count down from 150 and make its way to 130. When the train's speed exceeds that of the alert curve, an audible alarm sounds and the engineer must apply brakes within 8 seconds to avoid a penalty. Once the train's speed is returned to the civil speed limit, the alarm is silenced. However, if the engineer does not slow the train down and he exceeds the braking curve, penalty brakes are immediately applied. This penalty application is released once the train is at or below the civil speeds and is known as a "running release".

    ACSES can also enforce positive stop at interlocking home signals. This means that if the home signal at an interlocking is displaying a STOP aspect, the on-board ACSES apparatus will ensure the train comes to a complete stop before the signal. Additionally, ACSES can also enforce temporary speed restrictions in real time for situations such a work crews.

    HOW DOVETAIL GAMES DESIGNED THESE SYSTEMS
    Now let's discuss how Dovetail Games implemented these systems, starting with the cab signal system. In this DLC, the ADU does not properly conform to block conditions. I just loaded up a service starting at Newark Airport. I am on No. 1 track and will be switching to No. 2 track at Hunter interlocking. The home signal at Hunter is displaying Medium Clear, but the ADU is showing Clear. Since I am in the signal block before Hunter, the ADU should be reading Approach Medium and the MAS should be 45MPH. But since the current block conditions aren't being reflected on the ADU, ATC can't enforce the proper signal speeds and the ACSES braking curve calculations get messed up. Many issues with ATC and ACSES stem from the cab signal system not displaying accurate block conditions on the ADU.

    2.png
    Since the home signal at Hunter is a "Medium Clear" aspect, the signal block I am currently occupying should be "Approach Medium". The Cab Signal System did not pick up on this and believes the signal indication for this block is "Clear".

    Now to Automatic Train Control. The functionality of ATC is there, give or take a few things. If the ADU shows an aspect more restrictive than Clear, ATC will enforce the signal speed. However, the time to comply should be 8 seconds, not 5. Furthermore, upon applying the necessary braking and acknowledging the reduction in signal aspect, the audible alarm should stop. It doesn't.

    Let's talk about ACSES. Dovetail Games did program the functionality of enforcing civil speed limits and they implemented the braking curve calculations. But since the cab signalling system does not reflect current block conditions, the braking curve calculations get confused. Really, really confused. Upon spawning into the train at Newark Airport, the MAS showed 72MPH. I know that this is 90MPH track, the curve at Hunter is 70MPH, and that I am nowhere near the alert curve. 72MPH is very, very wrong. The reason it's showing 72MPH is because of the cab signal inaccuracies mentioned above. Remember I said that Hunter is displaying Medium Clear? That's a signal speed of 30MPH and the ACSES braking curve is taking that into account.

    If the system was functioning properly, my cab signals right now would display Approach Medium. The MAS would be 45MPH. As I got closer to Hunter, I would have to ensure the train is slowed to 30MPH by the time I got to the Medium Clear signal at Hunter. ACSES would enforce this. But since the block conditions aren't registering properly on the ADU, ATC can't act and the ACSES braking curve starts out a lot father than it should. Most of our issues stem from that.

    Now let's get into the issues with the signals themselves. There are lots of issues that need to be fixed such as running into Slow Approach signals at 45MPH, signal aspects not displaying properly...bulbs on the signals being out...more than one bulb on a signal head being illuminated...the list goes on. The signal aspects and their conformity to the cab signal system need to be revised.

    3.png

    HOW DOVETAIL GAMES CAN FIX THESE SYSTEMS
    1. Ensure current block conditions are accurately reflected on the Aspect Display Unit. Use the table posted above to ensure conformity. Here are some examples.
    • You pass an Approach Limited signal. The ADU should display either Approach Limited or Approach Medium in order to conform.
    • You pass a Restricting signal. The ADU should display Restricting in order to conform.
    • You pass a Clear signal. The ADU should display Clear in order to conform.
    2. Ensure the alarm is turned off at the correct time.
    • ATC alarms turn off when the proper braking is applied (suppression) and the acknowledge button is pressed.
    • ACSES alarms turn off when the train's speed returns to the civil speed limit.
    3. Fix the signal aspects and signal progressions.
    • We shouldn't see "Slow Approach" at all on the mainline. It's just not a normal aspect here.
    • Signals have natural progressions that gradually bring trains down to required speeds. We shouldn't be going from Approach Limited to Slow Approach. It just doesn't happen. Some common progressions are...
      • Approach --> Stop OR Stop & Proceed
      • Approach Limited --> Approach --> Stop OR Stop & Proceed
      • Approach Limited --> Limited Clear
      • Approach Medium --> Medium Clear
      • Approach Slow --> Slow Clear
    • The "C" lights on the signals shouldn't be used unless the wayside cab signal system has failed. The "C" light is used to tell trains with inoperative cab signal systems that the route is clear to the next interlocking. In the game I see this at Rea interlocking pretty frequently. It's nice that DTG made the signals display this, but it isn't necessary unless the cab signalling system has failed. And IF the "C" light is lit, the "C" light on the ADU should also be lit.
    • There are many examples of malformed/abnormal signal aspects in the route. I have seen tri-light/cluster light signals with all three bulbs illuminated with pure white. I have seen NYP signals with two lights illuminated on on the top, I have seen tri-light/cluster light signals with no bulbs illuminated at all on the bottom head...the list goes on.

    I hope Dovetail Games takes the time to fix these crucial systems. It makes the simulation much more enjoyable when these systems work properly. If anyone wants more details on how these systems work, just hit me up. I am happy to answer any questions you have.

    Thanks,
    Brandon


    DEFINITIONS

    AUTOMATIC BLOCK SIGNAL: A block signal that is activated either by track circuit or in conjunction with
    interlocking or controlled point circuits. This block signal automatically indicates track condition and block
    occupancy
    BLOCK: A length of track with defined limits on which train movements are governed by block signals, cab
    signals, or Form D.
    BLOCK SIGNAL: A fixed signal displayed to trains at the entrance of a block to govern use of that block.
    CAB SIGNAL: A signal that is located in the engine control compartment and which indicates track occupancy or
    condition. The cab signal is used in conjunction with interlocking signals and with or in lieu of block signals.
    DISTANT SIGNAL: A fixed signal used to govern the approach of a train to a home signal.
    HOME SIGNAL: A fixed signal governing entrance to an interlocking or controlled point.
    INTERLOCKING (Int): An interconnection of signals and signal appliances such that their movements must
    succeed each other in a predetermined sequence, assuring that signals cannot be displayed simultaneously on conflicting routes. Interlocking rules are in effect in an interlocking.
    SIGNAL ASPECT: The signal appearance, which conveys an indication as viewed either (1) from the direction of an approaching train, or (2) on the cab signal display unit in the engine control compartment.
    SIGNAL INDICATION: The required action conveyed by the aspect of a signal.
    NORMAL SPEED: The maximum authorized speed.
    LIMITED SPEED: For passenger trains, not exceeding 45 MPH; for freight trains, not exceeding 40 MPH.
    MEDIUM SPEED: Not exceeding 30 MPH.
    SLOW SPEED: Not exceeding 15 MPH.
    RESTRICTED SPEED: Not exceeding 20MPH outside interlocking limits, 15MPH within interlocking limits.
     
    Last edited: Mar 21, 2018
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  2. Anthony Pecoraro

    Anthony Pecoraro Well-Known Member

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    This is very useful and I did notice those signal issues in the videos that I have watched. Did you mention this? (See picture).
     

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  3. cActUsjUiCe

    cActUsjUiCe Well-Known Member

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    That is in the bug notes that I'm writing up. Thanks!
     
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  4. pschlik

    pschlik Well-Known Member

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    So the manual seems to suggest that the time to penalty should appear before the ACSES speed drops, and that going over the dropping ACSES speed would be bad-so it seems that the current implementation in DTGs mind is that the warning curve that the engineer sees is equivalent in function to the braking curve?
     
  5. cActUsjUiCe

    cActUsjUiCe Well-Known Member

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    The time to penalty will pop up when the alert curve is exceeded. It's to warn the engineer that he has X seconds to brake or he will get a penalty application.
     
  6. PlaysWithTrains

    PlaysWithTrains New Member

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    When the alarm is stuck on, you're down to the required speed, and pressing Q doesn't help, sometimes Tab, then Esc, then Q will stop it.
     
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  7. TrainSim-Martin

    TrainSim-Martin Staff Member

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    Hey folks,

    Thanks for posting up that doc Cactus, I've pinged this thread over to the development team to be incorporated into their next NEC update efforts.

    Best,
    Martin
     
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  8. cActUsjUiCe

    cActUsjUiCe Well-Known Member

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    Thanks!
     
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  9. idiosis

    idiosis Member

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    Did this issue get fixed in the end?
     
  10. cActUsjUiCe

    cActUsjUiCe Well-Known Member

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    Meh, some of it was fixed. The route is mostly playable, but there are still some major flaws with the signals and ATC/ACSES.
     
  11. geloxo

    geloxo Member

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    Apart from the "bicycle style" speed limits on the exit from Penn via its tunnels, one of the most annoying thing to me is the following (only happens in that particular point and travel direction): after Newark Penn in the direction of Secaucus Junction, the sign indicates 60 mph (Cab Speed). You arrive at a bridge over a river before entering Secaucus Junction and you have an unexpected and unwarned brake application.

    I have noticed that if you acknowledge after passing the 60 mph limit which is just before the bridge (when cab speed limit changes from 90 to 60) there is no brake application.

    I´m not sure if this is really correct, as the 60 mph limit has not long beep sound linked to it in ATC, which should be the one requiring you to press acknowledge button. There is simply a short beep. Does anyone know if this behaviour is correct at all?

    Cheers
     
  12. Anthony Pecoraro

    Anthony Pecoraro Well-Known Member

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    That is a bug. There should be a beep there too.
     
  13. geloxo

    geloxo Member

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    Thanks Anthony. I supposed that, but this error has been there for so long and after several updates I started to have doubts. I hope it´s fixed.

    Cheers
     

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