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Thread: Long Train Operation

  1. #31
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    A Question: Will Ian Macmillan's MSTS Measuring Tool for Shape File viewer be accurate enough to determine the following for railcars?
    ORTS... LengthCarBody; LengthBogieCentre; and LengthCouplerFace

    For diesel locomotives those measurements appear to be common in manuals and specifications, although I'm having trouble finding that specific information for the Alco RSD15 and 17.
    Cheers, Gerry
    It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.
    Forever, ridin' drag in railroad knowledge.


  2. #32
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    Quote Originally Posted by PerryPlatypus View Post
    I have experienced similar issues on Mullan, which has me concerned. Running a 3x4x1 coal train up the grade, was getting constant derailing, even in areas of very broad/gentle curves. In the case of both this coal train and the Z Train Reroute consist, they are very very homogenous consists of all loads of similar car length, and all cars being nearly identical weight. These consists are also based on prototypical consists that run over this route without issue daily.

    The coal train is 3 locos up front, 67 coal loads, 4 mid-train helpers, 58 more coal loads, then 1 DPU. Grade is 2.2%. The derailment was happening right at or very near to the mid-train helpers, so I am thinking the sim is being overly sensitive to the large in-train forces happening at the mid-trains.

    Either there is a flaw that we (the TrainSimulations) team have introduced unknowingly in our WAG or ENG files that never surfaced previously because this type of derailment detection was not a thing... or, there is an error in the new code.

    Either way, I am actually in agreement that it would be nice to figure out the solution to the problem, as I am always a fan of realism
    Sean, I am getting ready to finish that "Z Train Route". I stopped it at Blossberg{had something to do}. I will let you know if and when the problem manifests itself if you wish. Brian

  3. #33
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    The wheel profiles used in the simulations were obtained from the transit system survey. These profiles were applied to simulations of both light rail and rapid transit vehicles with flange angles ranging from 60 degrees to 75 degrees and flange length ranging from 0.395 to 0.754 in.
    From Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations (2005) --- The National Academies Press https://www.nap.edu/read/13841/chapter/8

    Another Question: The above underlined/bold information applied to trainsit rail --- is it also applicable to freight?
    Specifically these two parameters --- ORTSWheelFlangeLength and ORTSMaximumWheelFlangeAngle?
    Cheers, Gerry
    It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.
    Forever, ridin' drag in railroad knowledge.


  4. #34
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    Quote Originally Posted by motormaster532 View Post
    Sean, I am getting ready to finish that "Z Train Route". I stopped it at Blossberg{had something to do}. I will let you know if and when the problem manifests itself if you wish. Brian
    Just finished "Z Train Re-Route". I picked it up where I last left off at Avon. The Derailment notifications DID NOT come in at all the rest of the way. I used harder Dynamic Braking as well as hard Trainline braking than I normally would in the Sim,harder than I COMPLETELY would have in real life! No Problem! An excellent Activity in an excellent Route. Thank you Sean and Everybody else. I am going to PM you with this. Brian

  5. #35

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    If you're trying to fix long-train wheel/rail dynamics, don't base anything on that report. About the only thing that a long and potentially heavy train has in common with a rapid-transit system is that they both run on rails, and sometimes not even that!

  6. #36

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    Hi Sean,

    Quote Originally Posted by PerryPlatypus View Post
    It might be a bit until I can respond to set up a formal testing scenario with you, but I'll email you when I get some time in the coming weeks to do that.
    No problems email me when you are ready.

    Before you do, can you have run the derailment test route that I have setup, and skimmed through some of the documentation linked in the route documentation.

    Quote Originally Posted by PerryPlatypus View Post
    There is a statement that when these values are not explicitly specified (which would be the case with any of the Mullan content), that they are estimated from information in the WAG. Obviously I am curious what formulas are used for estimating these values.
    It tries to use any default information that is available in the WAG file.

    For example it uses the Size statement, however this is not always accurate as it is sometimes adjusted by users to get the "visual" effects of the SIM working correctly. It also uses the NumWheels statement (in older MSTS files), and again this is not always accurate.

    For some of the other values it uses "guesstimates".

    As I have suggested in my site, wherever the highest level of accuracy is desired the "default" information should be over written by accurate prototypical information.

    The Lateral Force on the car is influenced by the coupler angle, hence why it is more at risk of a derailment on a sharpe curve, and some of the parameters indicated by you will influence the coupler angle.

    Quote Originally Posted by PerryPlatypus View Post
    I do want to bring up the issue of superelevation as a potential cause.
    Superelevation is already considered in the derailment calculations.

    It should be noted that there are currently two "separate" superelevations at work in OR. The first one is purely for visual effects, and is set through the OR Options Menu.

    The second one, which impacts the physics, is set with some "standard" defaults, but can also be overwritten with values in the TRK file. I assume that these are the values that you have set.

    My personal preference would be to see the two merged into a common input arrangement. The visual one only allows the user to specify a single superelevation value for the whole route, whereas the other approach, whilst not as good as setting the superelevation in the track database does at least allow more variations.

    Quote Originally Posted by PerryPlatypus View Post
    However, as I'm sure you know in the real world, this superelevation can vary significantly from one curve to another on the same railroad, even between two curves with the same radius. It's all a matter of design track speed for a particular spot.
    I agree that this can happen. If the full route has been designed to a common speed, then the correct amount of superelevation should be designed into the curve such that the train can safely travel around the curve at the indicated route speed. Where different superelevations are used for the same radius curves throughout the route, then I would expect to see different speed limits to apply on these curves. And if these speed limits are adhered to then this should ensure that operations will be within acceptable performance limits on most occasions.

    At the moment, based upon my test scenario, and testing to date, I believe that superelevation is adequately considered within the derailment calculations.

    Until I see your scenario in more detail I cannot offer any more suggestions.

  7. #37

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    Quote Originally Posted by R. Steele View Post
    Another Question: The above underlined/bold information applied to trainsit rail --- is it also applicable to freight?
    Specifically these two parameters --- ORTSWheelFlangeLength and ORTSMaximumWheelFlangeAngle?
    You may wish to have a look at the derailment thread on ET, as it has some links to documents which might help answer your questions.

    http://www.elvastower.com/forums/ind...ost__p__276617

  8. #38
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    Quote Originally Posted by steamer_ctn View Post
    You may wish to have a look at the derailment thread on ET, as it has some links to documents which might help answer your questions.

    http://www.elvastower.com/forums/ind...ost__p__276617
    Thanks, with other sources I've found, and the link at Elvas, yes I'm in the ballpark...0.754in for flangelength and 75 degrees for flange angle ( 1.308996rad ) will be my starting testing values.
    Cheers, Gerry
    It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.
    Forever, ridin' drag in railroad knowledge.


  9. #39
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    Honestly, at the moment, I turn off derailments. If a train of the same car type, length, etc, derails, that I run almost daily with no issues in the real world, something isn't adding up.

    At least everything else in ORTS is getting pretty good with the realism aspect. Air pressure depending on the length of train and how quick it climbs, curve dependencies, etc.
    https://i.imgur.com/LPZNEX4.png

  10. #40
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    Yep Flange info is important an I forgot to point that out.

    Pre 2005 I typically use:
    ORTSWheelFlangeLength ( 1.0in )
    ORTSMaximumWheelFlangeAngle ( 70deg )

    Modern today equipment I typically use:
    ORTSWheelFlangeLength ( 1.25in )
    ORTSMaximumWheelFlangeAngle ( 75deg )

    I also point out wheel size is important too as there is a difference in starting force an turning rounds. If you are like me I get annoyed at the fast turning wheels in pre stock at slower speeds as if wheels were small but vulnerable to derailing like intended for some autoracks with small wheels with a bunch of cases of string lines.


    Quote Originally Posted by R. Steele View Post
    A Question: Will Ian Macmillan's MSTS Measuring Tool for Shape File viewer be accurate enough to determine the following for railcars?
    ORTS... LengthCarBody; LengthBogieCentre; and LengthCouplerFace
    I barely used that tool an appears to be an accurate easy way to measure an move then what I been doing. But trying the tool vs the bounding info shape viewer shows, it looks pretty easy positioning the center green lines to the point of measure an multiplying it by 2 or measure both ends an add up. I would later convert to feet.

    Thanks

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