How much snow to stop a train?

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How much snow to stop a train?

  • Whether its a RR crossing pile left by a plow truck or a 100 yard snowdrift out in the boonies, how much snow does it take to stop a train?

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  • No simple answer.  It will depend on the initial momentum of the train (speed and/or weight) and what type of snow.  Powder, like skiers love, will basically blow away.  The opposite type is a hardpacked drift in a shallow cutting.  The latter has been known to to derail a train, which then stops really quickly.

    John

  • Here's three engines and a wedge plow getting stuck from about 40MPH -

     http://www.youtube.com/watch?v=tF2ZPRmocs4

  • Speaking of that train getting stuck at 40 mph, I've noticed a lot of time with plow trains it's just a plow with 3 engines. My guess would be why not put it in front of a full freight? That would give it a lot lot more momentum to plow through the heavy drifts. I'm also guessing there is a reason why this isn't done, and that reason is?
  • You can stop a snow plow with 2 or 3 locomotives pushing from behind rather quickly...stopping a 100 + car freight train takes a good long time..

    You can stop, back up and hit a heavy drift repeatedly with the small plow/locomotive combo, you can't back a train up easily or quickly.

  • Someplace a year or two ago I saw or read an explanation by a motive power person as to why it's easier to get stuck with a plow being pushed by - say, 3 locomotives - as opposed to just 1.  It was counter-intuitive, of course, but made sense when studied.  I can't replicate the rationale - maybe with some luck I'll be able to find it and link it here - unless someone else can explain it here first ?

    - Paul North.

    "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
  • I'd imagine it because if you only have 1 loco you can only push so deep into the snow - with 3 locos you can push deeper. Which means you'd be able to push through a deeper drift - to a point. When that point is reached, and you get stuck, you're in way deeper snow in the first place than you'd be with just 1 loco.
  • I think it was more like the 'weak link' principle - that sooner or later, one or two of them were going to start to slip, and at that point they became worse than useless - they were also added dead weight that had to be dragged along, and so would cause the more reliable loco/ stronger link to slip, too, so the whole shebang would come to a halt.

    Which raises the question of why send more than 1 loco out with a plow anyway.  The only answers I can think of are reliability and safety - if 1 quits and shuts down,the crew can take refuge in another one and maybe use it to get back home - and to provide more weight = momentum for ramming drifts before they slow down enough that tractive force / slipping governs what they can do.

    But I could be wrong on some or all of that.  I'd really like to see what an engineer or Road Foreman with experience in this has to say about that.

    - Paul North.

    "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
  • I could be wrong, but it seems to me that running a wedge in front of 2K tons or more increases the probability of a serious wreck.  For one, the plow, itself, only weighs so much...in the right circumstances could it not be lifted off the tracks, buckle back, do a lot of damage...?  If in compacting snow it creates a near hydraulic block to its front, what happens to the rest of the moving items behind....would they slow and stop commensurately, or would the risk of a derailment, broken/shoved couplers, etc be considerable?

    -Crandell

  • Yes - and it has and does happen - although, the upward-sweep of the wedge causes a reaction force that pushes the fromt of the plow down and tighter/ harder onto the rails.

    Then you have a 'reality-show' full size and actual-time demonstration of the answer to the rhetorical and scientific question of, ''What happens when an irresistable force meets an immobile object ?''  Where are the Myth Busters when we need them ?  ''Something's got to give'' - sometimes it's the snowpack, sometimes it's the snowplow train . . . Whistling

    - Paul North.

    "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
  • Paul_D_North_Jr

    I think it was more like the 'weak link' principle - that sooner or later, one or two of them were going to start to slip, and at that point they became worse than useless - they were also added dead weight that had to be dragged along, and so would cause the more reliable loco/ stronger link to slip, too, so the whole shebang would come to a halt.

    Which raises the question of why send more than 1 loco out with a plow anyway.  The only answers I can think of are reliability and safety - if 1 quits and shuts down,the crew can take refuge in another one and maybe use it to get back home - and to provide more weight = momentum for ramming drifts before they slow down enough that tractive force / slipping governs what they can do.

    But I could be wrong on some or all of that.  I'd really like to see what an engineer or Road Foreman with experience in this has to say about that.

    - Paul North.

    When running the wedge or Ditcher,  you need a way to bring the plow back home.   Speeds are restricted, when running them backwards as well.   So operationally, you want a back to back pair.  Yes, you also want power to buck the drifts.    Back a few years ago, we took 3 B23-7's out with the ditcher on the branch.  And as you predicted, one shut down ground relay.   Normally however, two is the norm on these parts.  

    The only time we ran a single unit was on the old CGW in Hampton.    Had the wedge plow in April, and sure enough, it went off in the cut going to Coulter.    Nothing serious, but they are just not as stable as the Ditchers.  

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  • .

  • From the Railroad Gazette:

      

    February 1888

     

    10th, on Northern Pacific, near Grey Cliff, Mont., passenger train derailed in a snow drift, the entire train running free from the track upon the prairie, leaving the road unobstructed.  The locomotive was upset and the tender piled on top of it.  Engineer and fireman killed.

  • Kootenay Central
    ...Definitely stopped...

    I dunno....I think he's still got a chance.   Maybe the boiler will melt back some of what's holding him?

    Laugh

  •  In January 1951 the City of San Francisco got stuck when try to pass through a snow drift and then was hit by an avalance in the Sierra Nevada Mountains.  Th rotary plow sent to dig them out was hit by an avalance and buried.  It took three days to get the passengers and crew off and another week to clear the line to allow traffic to flow again.  It is not just drifts that snow plows have to worry about

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