Santa Fe Junction, again?

BoxcabE50 Dec 19, 2022

  1. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    Saw a clip on YouTube. Apparently this past Tuesday, (12/23/22), there was another derailment there. Seems as though there have been several this past year or two. This has me wondering. In this one, the cars again rolled to the outside of the curve. :eek::confused:
     
  2. Kurt Moose

    Kurt Moose TrainBoard Member

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    Seems almost to be a string-lining issue, maybe that curve is too sharp?

    Luckily, no damage to the trestle again, this time!
     
  3. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    But this was another instance of the cars rolling outside the curve, at the same site, under the bridge. Just the opposite of a string line.
     
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  4. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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  5. Randy Stahl

    Randy Stahl TrainBoard Supporter

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    Jack knifed. obviously, the rear of the train was moving faster than the front.
     
  6. Kurt Moose

    Kurt Moose TrainBoard Member

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    Yeah, I could see that happening. Wonder if it's a weird area, DPU not communicating?
     
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  7. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    I am also wondering. Possibilities would seem to be slack action? DPU? It appears to be relatively level terrain. The train seemed to be moving at an even pace. Should have been essentially stretched out. Your thoughts, Randy? Anyone else?
     
  8. HemiAdda2d

    HemiAdda2d Staff Member TrainBoard Supporter

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    If DPUs are not shoving at the same rate as the head end, this can definitely occur. The monster trains of today being double or triple the length as those when the bridge was built probably exacerbates the issue. But I'm not a railroader and didn't stay at a Holiday Inn Express last night, so there's that...
     
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  9. r_i_straw

    r_i_straw Mostly N Scale Staff Member

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    I remember back in April 2012 when the UP 844 steamer was coming down into Texas from Arkansas, the crew applied engine brakes and the diesel MUed behind the water tenders and the tool car went all crazy and went to notch 8. They did not hear it and kept applying more brakes until the 844 locked up and started sliding. Made some nice flat spots in the drivers before they got everything stopped. At least it was not on a curve.
     
  10. gjslsffan

    gjslsffan Staff Member

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    Listening to the squeal of those flanges, that appears a pretty sharp curve. DP can sometimes lag in response to throttle or dyn applications, I wonder if there are any comm issues around there. It appears to me to be buff forces shoving those cars off the track. Is there a grade leading to that curve? Train make up or a host of other forces at play could have led to this incident. Curious to see why these derailments are happening at this location.
    I heard a bang before they went on the ground, like the slack was coming in on them. On a sharp curve with MT's you can shove them off the track easier than you might think.
     
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  11. mmi16

    mmi16 TrainBoard Member

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    PSR is railroading by the Finance Department. The department that knows the price of everything and the value of nothing.

    With PSR's precepts demanding longer and heavier trains, the physical characteristics of a territory that were not any kind of problem in the past become a problem 'all of a sudden'. That 5000 foot train that only encountered a single 'mound' or 'sag' within its train length had a operating practice designed for crews to negotiate that territory with little trouble. Then the train length was increased to 9000 feet and additional physical characteristics were encountered by the foot print of the train - additional locations where the slack would change within the train - increasing draft and/or buff forces within the train as it moves over the territory - the longer the train the more difficult it is for the engineer to control those buff and draft forces using the tools he commands engine pulling power and braking power, either train air brakes or engine independent or dynamic braking. Now that trains have increased in length to 12000 and 15000 feet it is just that much harder for the engineer to control his train over an even longer footprint of varying territory.

    I am not familiar with Santa Fe Jct., however, with its visible bridges, it is at a water level location with a river (Missouri River?). Rivers create valleys, valleys that they flow through in normal times and flood plains that get flooded during extraordinary times. The flood plains are bounded by areas of increasing elevation as the ground moves away from the river. Railroads TRY to use a route with the least possible elevation change as they move away from the water crossing, some have little elevation change, some have a lot. Considering the curvature that exists on some of the routes visible at Santa Fe Jct. is doesn't take that much elevation change 'away' from the river to give a train moving toward the river a lot of BUFF forces acting upon car negotiating the curves.

    Empty cars have less 'track holding force' when subjected to either BUFF or DRAFT forces than do loaded cars, long empty cars have even less track holding force in curves as they are also subject to angles that create a 'jacking' force upon the cars.

    With the most recent video of the train derailing at Santa Fe Jct. the BUFF forces of the rear of the train forced empties off the high side of the curve. The fact that the rear kept moving and derailing cars after the first car derailed and activated the air brakes in emergency is further evidence of the BUFF force on the train at that physical point. I don't know how long or steep the grade is approaching Santa Fe Jct. is, but the derailment makes it obvious that it can derail a train.

    As a general rule - BUFF forces will derail cars to the outside of a curve. DRAFT forces will derail cars to the inside of a curve.
     
    Last edited: Dec 26, 2022
  12. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    SFJct.jpg
     
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  13. Randy Stahl

    Randy Stahl TrainBoard Supporter

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    You can do alot of damage with the train bunched and with 240,000 lbs of head end braking effort on a sharp curve. This isn't the last time.
     
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