1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

(northeast Corridor: New York) Acses Apparatus Functionality

Discussion in 'General Discussion' started by cActUsjUiCe, Mar 5, 2018.

  1. cActUsjUiCe

    cActUsjUiCe Well-Known Member

    Joined:
    Sep 21, 2017
    Messages:
    240
    Likes Received:
    591
    Good afternoon,

    I am wondering how much of ACSES (Advanced Civil Speed Enforcement System), the Positive Train Control used on the Northeast Corridor was implemented in the NEC: NY route.

    For those who are unaware, ACSES is an extremely complex PTC solution. Some of its most prominent features are:
    1. Enforcing positive stop at interlocking home signals. This means that if the home signal at an interlocking is a STOP signal, the on-board ACSES apparatus will ensure the train comes to a complete stop before the signal. The train will usually stop within 1,000 feet of the signal. This is enforced via ACSES transponder sets place in the track gauge just before the home signals.
    2. Enforcing Temporary Speed Restrictions (TSR). The dispatcher can implement TSR's for certain areas in real-time. The on-board ACSES apparatus can receive and enforce these speed restrictions.
    3. Calculating a maximum safe braking curve. The on-board ACSES apparatus knows how far the train is at all times from upcoming speed restrictions. It is also aware of the current speed of the train. With these two pieces of information in mind, it is constantly calculating a safe braking curve for upcoming speed restrictions. Once the train gets close to exceeding this braking curve (also known as the "Alert Curve"), the Aspect Display Unit (ADU) will start gradually lowering the Maximum Authorized Speed and force the engineer to apply brakes and acknowledge the speed reduction. If the engineer does not acknowledge in time, an ACSES brake penalty is applied. This automatic braking curve calculation isn't meant to replace the engineer's knowledge of the physical characteristics of the area and is only in place to ensure the train complies with Permanent Speed Restrictions.
    Here is a graphical representation of the braking curve, courtesy of Siemens Inc.
    Capture.PNG

    Here is a photo of the Aspect Display Unit, also courtesy of Siemens Inc. You'll see this in the ACS-64 cab when operating in NEC: New York!
    ADU.PNG

    The numerals underneath "Maximum Authorized Speed" (MAS) will always display the maximum authorized speed for your specific train (in miles per hour). Since the ACS-64 with Amfleet I coaches is an ACSES Type "B" consist, Type "B" speeds will be enforced. There are different train types (A through E) on the Northeast Corridor (except between New Haven and New York). ACSES will enforce these varying speed limits based on the train consist.

    As stated before with the braking curve, the numerals underneath MAS will start to decrease in value when the "Alert Curve" has been reached. For example, you are in 60MPH territory and there is a 40MPH curve ahead. Once the "Alert Curve" has been reached (as calculated by the on-board ACSES apparatus), the numerals in MAS will start to decrease from 60. It could show 59, then 57 a couple seconds later, 55 a couple seconds after that, etc. Once the alert curve has been reached, the engineer must control the train accordingly in order to avoid an ACSES penalty.

    Now for a real-world example. There's an awesome video on YouTube titled "SEPTA Fox Chase Line ACSES (PTC) Tutorial Northbound" which illustrates the braking curve functionality perfectly. NOTE: SEPTA uses a different version of the Aspect Display Unit, but the functionality is similar. A trainee engineer was at the controls.



    At 4:25, the train is in an area where the MAS is 50MPH. The train is traveling 42MPH. There is a 30MPH restriction ahead. the ACSES apparatus is aware of this but is the trainee engineer aware?
    1.PNG

    At 4:31, the ACSES Alert Curve takes effect. This is known because the numerals beneath "Maximum Authorized Speed" start to decrement from 50 (the MAS in the area). At this point, the engineer has to ensure he brakes in such a way that his actual speed doesn't go above the maximum authorized speed for a prolonged period of time. If it does, an ACSES braking penalty will apply.
    2.PNG

    So back to my question. Was any ACSES functionality programmed into the NEC: NY route?

    Thanks and let me know if you have any questions,
    Brandon

    Want more information about ACSES? Siemens has an excellent article. https://w3.usa.siemens.com/mobility/us/en/Events/railway-interchange/Documents/SIE_BRO_ACSES.pdf
    This video is a bit corny, but is pretty accurate.


    Feature differences between Cab Signal System (CSS), Automatic Train Control (ATC), and Advanced Civil Speed Enforcement System (ACSES).
    acses.PNG
     
    Last edited: Mar 5, 2018
    • Upvote Upvote x 9
  2. pschlik

    pschlik Well-Known Member

    Joined:
    Dec 8, 2016
    Messages:
    875
    Likes Received:
    1,533
    So when does that time to penalty thing come in? I see the SEPTA thing doesn't even have that on its panel, even though it's not that different otherwise. Is that just something unrelated to ATC and ACSES or just not needed?
     
  3. cActUsjUiCe

    cActUsjUiCe Well-Known Member

    Joined:
    Sep 21, 2017
    Messages:
    240
    Likes Received:
    591
    My understanding is that ATC requires the operator to acknowledge signals. So let's say you had a CLEAR aspect at 70MPH and then passed an APPROACH LIMITED signal. ATC will require you to acknowledge the reduction in signal aspect and begin slowing the train to 45MPH, otherwise the train will have a penalty brake application.

    ACSES requires the engineer to take action in order to comply with civil speed restrictions (the actual speed limits of the route, not the signals). So if you are on a 150MPH piece of track and there is a curve coming up which is 130MPH, ACSES will enforce BOTH the speed of the track you are currently on (150MPH) AND ensure the train is controlled in such a way that it'll be going 130MPH by the time the curve is reached.

    The penalty comes into play with both acknowledging reductions in signal aspect AND speed limits. The SEPTA display unit doesn't have a penalty countdown, but it is inherently 8 seconds.

    To quote actual ACSES rules...

    "When the track speed indicator changes to a more restrictive speed, the audible indicator will sound until the
    speed change is acknowledged. Failure to acknowledge the change within 8 seconds or to satisfy the required
    braking rate will result in a penalty application of the brakes.

    When the track speed indicator changes to a more favorable speed, the audible indicator will transmit a short
    sound, which will not require acknowledgment. Speed must not be increased until the entire train has cleared
    previous lower speed limit."

    I hope this answers your question.
     
  4. cActUsjUiCe

    cActUsjUiCe Well-Known Member

    Joined:
    Sep 21, 2017
    Messages:
    240
    Likes Received:
    591
    In addition, I found this image which I'll put into the original post.

    acses.PNG
     
  5. cActUsjUiCe

    cActUsjUiCe Well-Known Member

    Joined:
    Sep 21, 2017
    Messages:
    240
    Likes Received:
    591
    So I read over the manual that was recently released and it appears that the braking curve functionality was implemented. I am very glad that DTG took the time to do this. It'll be fun to test this out on the 20th!
     
    • Upvote Upvote x 2
  6. LastTrainToClarksville

    LastTrainToClarksville Well-Known Member

    Joined:
    Oct 12, 2017
    Messages:
    851
    Likes Received:
    615
    One big step for curve functionality, one massive confusion for this 73-year-old. Yes, I know that all of this can be disabled in the sim, but then I'll feel guilty for not taking full advantage of the experience the sim offers and arrive at stations on time only by sheer dumb luck. I'm not complaining, just sharing mental notes.

    Added later: after studying the manual some more, it occurs to me that two things would be very helpful:
    1. a revised manual or a supplement that provides images of these various safety devices as they appear on the control console, each numbered to correspond to numbers inserted in the text, and,
    2. an additional tutorial session dedicated to these safety systems and their use while driving.

    What we have now is the equivalent to a driving teacher who describes the location of a car's controls in a classroom and then puts the student in a car and just walks away. This is especially true since it isn't possible to tab back and forth between simulator and manual while operating a train.

    Please consider these needs seriously, developers.
     
    Last edited: Mar 24, 2018
    • Upvote Upvote x 6
    • Downvote Downvote x 1

Share This Page