Derailment analysis, followup

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  • geepster775
    2500 Post Veteran


    • Sep 2006
    • 2846
    • .
    • General

    #1

    Derailment analysis, followup

    I attempted to recreate in OR this real life scene at the Austin horseshoe on Mullan.



    So I created a temporary installation with just the Mullan route and the Mullan expansion pack.

    I used 2 Mullan-era Dash9s.

    The original video showed 63 loaded wells (with empty containers, likely) followed by 60 empty wells. I used the same BNSF car number for 12 of the 5-pack loads, and one 3-unit Thrall DTTX for a total of 63 'lightly' loaded wells. I then used 12 of the same DTTX 5-packs for the 60 empties on the rear.

    I found some builders stickers of various BNSF C44-9Ws, one in the 4300 series and one in the 5100 series, and both said 415,000 pounds, so I adjusted the weight of the engines to 207.5 US tons up from 200 or so (I think they had been set at 181 metric, or in that area). I think BNSF Gevos come in around 416,000 pounds in real life, with the exception of the new 3600 series which are non-C4 heavies, at 432,000.

    I found some Greenbrier data that claimed the Maxi-1 5 unit well car weights 177,200 pounds, or 88.6 US tons, or roughly 17.7 US tons per empty well. TS had used the figure of 17.5 metric tons which is about 19.5 US tons per well, a shave heavy. The tonnage for the loaded car was adjusted for to 27.5 US tons (17.5 US tons empty well weight plus 9,000+ pounds, 4.5 tons-ish each per empty container, rounded up to 10 tons for double stack empty container weight). Empty wells were set at 17.5 US tons.

    For the outside A and B wells, I replaced the numwheels line with

    ORTSNumberAxles ( 3 )
    ORTSNumberBogies ( 2 )​​

    For middle three C, D and E wells.

    ORTSNumberAxles ( 2 )
    ORTSNumberBogies ( 1 )​​


    Train stats in TSRE CE were 3207 US tons, 6,696 ft, 125 "units" (2 eng, 63 ld wells, 60 mt wells).

    The first two 5-packs derailed the middle 3 platforms. The third 5-pack derailed only the single middle well. Derailment coefficients were in the 1.4 range. The fourth 5-pack spiked the middle well at about 1.36, not enough to trigger a derailment message. Prior to making the weight adjustments, I was getting derailments on the middle 3 platforms for practically the entire front half. Derailment coefficients were in the 2.4 range on those middle 3 platforms, the value tapering off slightly the further the train progressed around the curve. Also with the heavier original values for the cars, I was about 1.5 mph slower up the grade in 8th notch unassisted.

    My Open Rails videos https://www.youtube.com/@lakecities3663/videos
  • geepster775
    2500 Post Veteran


    • Sep 2006
    • 2846
    • .
    • General

    #2
    Here are my test path, consist, and eng/wag file adjustments.
    Attached Files
    My Open Rails videos https://www.youtube.com/@lakecities3663/videos

    Comment

    • PXSE
      Senior Member
      • May 2011
      • 144

      #3
      I think there is an issue with the derailment coeffient value jumping around and spiking high needlessly. The fact that we cannot simulate what happens in the real world is something that needs to be looked at. I noticed that the derailment messages were being displayed in some of the screenshots of the new Sand Patch route under development.

      Comment

      • c44d9w
        Member
        • May 2010
        • 58

        #4
        The derailment coefficient is the ratio of lateral force to vertical force at the wheel.
        The vertical force is based on the weight divided by the number of wheels. Superelevation and centrifugal forces are also considered.
        The lateral force is highly influenced by the curve radius. MSTS, and thus OpenRails, has discrete radi for curves. That explains the jumps in the derailment coefficient.

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