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Repair/construction trains
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Dogoth
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Repair/construction trains
 
« on: May 13th, 2014, 7:43pm »
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Where was my camera
 
I saw 3 trains the other day 1) carrying just rails 2) carrying all of the construction equipment 3) carrying nothing but obviously to pick up the worn out replaced rail, ties etc... (same type of specialized cars carrying the rail).
 
Train 1 looked to be 20+ cars and it APPEARED that they were spanned with 60+ REALLY long sections of rail. How do they make corners? About every 5th car there was a raised platform with a couple of spotters to keep an eye on the cargo. I don't see how 1400+ feet of rail can be transported around corners. If it were just a couple of pieces, I guess they could bend ( Case hardened at normal outdoor temperatures - Maybe not - ouch) but this cradle arrangment with so many pieces would NEVER bend. Are the trucks articulating? even then..... How do they do it?
 
FWIW I heard radio traffic suggesting that they were repairing/replacing roughly a 1 mile section (about 5 miles from my location).
 
Where was my camera


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George_Harris
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Re: Repair/construction trains
 
« Reply #1 on: May 13th, 2014, 8:15pm »
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Where are you seeing this?
 
Welded rail bends quite nicely.  A short piece may act quite stiff, but a long piece of rail bounces and bends quite a lot.  A fully loaded rail train will quite nicely negotiate curves of under 500 feet radius.  A single layer of rail on a rail train will go around a 300 feet radius curve.  Wasn's supposed to, but the contractor I was working for at that time didn't know better and pulled it through.  Did fine.  Sometimes it works out quite will when you try and do things you did not know you were supposed to not be able to do.
 
Please note:  The rail on a rail train is clamped at only one location, about mid string.  The rest of the support points are rollers.  Otherwise, you will derail the the train.  Even though the difference in radius of the rail itself is 10 feet or less going around a curve, that is significant.
 
Sounds somewhat like you were seeing single sticks of rail for installation as jointed rail.
 
Rail is a high hardness high strength carbon-manganese steel, but high ductility is most important.  Brittleness is death, quite literally, in rail.  there is a head hardening process, but the current standard hardness spec is about where the head hardness spec was 40 years ago.


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Dogoth
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Re: Repair/construction trains
 
« Reply #2 on: May 16th, 2014, 10:36pm »
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Thanks George for the info. I saw another one (or more likely part of the same one). This time (still no darned camera at hand).  
 
You asked where. UP track CPRV252 Roseville sub about 5 miles east of the Sparks NV yard. The repair they were doing earlier was about another 20 miles east near a small town called Fernley NV. I wanted to go watch BUT I do my best to stay out of the way of any construction/repair personel so I didn't.
 
This time I scrutinized it as closely as possible (it going 44 mph per a nearby detector). It had 12 cars with the spotter platform at car number 6. Again it appeared that the rails were all continuous pieces but it could (as you  say) been split and fastened under the platforn. They looked like slightly shorter than average cars (est 40' + couplers & frame). That makes more sense putting the rails at around 300'.
 
It makes sense that you wouldn't want hardened steel as it would crack/shatter (Pliability being the name of the game). Do they harden just the top running surface though (to give it some longevity)?
 
Fascinating just to see it though.
 
Cheers


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George_Harris
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Re: Repair/construction trains
 
« Reply #3 on: May 17th, 2014, 1:23am »
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The normal length of rail on a welded rail train for years has been in the range of 1,400 feet.  There is nothing magic about this number.  It could be either more or less.  In transit system work it is usually half that.
 
The standard freight car length for years was 40 feet in the past, but that is no more and has been gone for quite a while.  Now the normal length of a single car is usually 50 feet or more.  In fact, they are all over the map depending upon commodity and how long it can be before the load per axle gets to be regarded as too high.  The usual 4 axle car gross weight limit is 263,000 lb., 286,000 lb., and for some up to 315,000 lb.  Obviously the heavier the car the more limited the lines on which it can operate.  
 
There is a standard zone for head hardening.  It is the top and sides of the head only.  It is a heat treatment process.  As said, requiring head hardening is not as common as in the past because the hardness specified for the whole section has gone up.  Also, heat treating the head causes issues at the welds, particularly field welds, as welds introduce variations in hardness in the rail.


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