Yesterday, while at one of my favorite trains watching spots, which includes a moderate curve, a long BNSF freight train passed. Most of the cars went through the curve without the flange hitting the rail, which I presume was the cause of the screech, but the wheel flange on several cars at various locations throughout the train were touching the rail as indicated by a loud screech.
Why would most of the cars get through the curve without the flange touching the rail but not all of them?
Rio Grande Valley, CFI,CFII
It has much less to do with the flanges than it does with the solid axle between the wheels.
When passing through a curve, one wheel will be sliding at least a little bit. Which one depends on a variety of factors.
When that sliding occurs, you'll often hear the squeal. Tune in to the Desher rail cams for a regular dose.
Several things can affect the squeal. Dry rail is one - wet rail lubricates the contact and the sliding is relatively silent. Weight is another. An empty flat car is no where near as noisy as a loaded coil car.
Curves on the transfers at Deshler are 10 MPH. I haven't really listened to trains on broader curves or at higher speeds.
If you can manage a close-up view of the roadbed on a sharp curve, you'll likely see flakes of metal on the ballast from the sliding.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
My house is 1/2 air mile from Sykesville's station (operating as Baldwin's Restaurant) on the CSX's Old Main Line - the track follows a series of curves following the Patapsco River.
There are occasional notes of rail singing as the coal trains pass through town. The OML does have several 'greaser' locations along its length.
Never too old to have a happy childhood!
How freely a truck swivels on its center plate can affect the amount of flange contact on curves. The center plates are lubricated but can run dry over time.
I have seen metal flakes on the ties and ballast near the outer rail on sharp curves with none near the inner rail. I think the flakes come from the gage side of the railhead and the wheel flanges rather than the wheel tread. The gage side of the outer railhead was noticeably worn while the inner rail gage side was not worn at all.
(Center Bound trucks) .... big concern especially on certain locomotives and articulated cars
pretty much the opposite of truck hunting
I would only be guessing, since I'm not in the business, but tires and rails that are both well along in their cycles of utility probably also have a bearing on noise. Tires eventually leave their profile of a truncated cone as they wear. I would guess that the contact profile changes as a result, and also the place where the contact takes place. That might increase both scrubbing and noise, along with radius.
I'm in a rail-side bar with friends in the west end of Toronto- The Blue Goose to be exact, a great old neighbourhood pub where the actual foot rest at the bar is a length of rail- the VIA and GO Transit yards are nearby. When the GO trains go by they don't make any noise- freights made screeching noises. My question is, do the GO train coaches have a solid axle?
I thought the wheel taper was supposed to compensate for the difference in distance traveled as a train rounds a curve. The wheelset moves to the outside so its outer flange runs against the inside of the outer rail. That would be only the flange fillet, and not the entire flange wall. Then with the wheelset shifted off center like that, the outer wheel is riding higher on its taper than the inner wheel.
EuclidI thought the wheel taper was supposed to compensate for the difference in distance traveled as a train rounds a curve.
To a point. For most mainline curves that will work. On a tight, slow curve, not so much. We regularly get squeal on our 5.5 degree curves at 25 mph. I don't know what the transfers/wyes at Deshler are.
Euclid -
That principle is valid only for a range of curves, from tangent up to some radius that I don't know how to compute tonight (too many variables, constants, and formulas that I don't have at hand). In principle, it would be the different diameters at the contact points - near the flange on the outer rail and hence a longer circumference, and further from the flange on the inner rail and hence a shorter circumference - the taper is 1:40, IIRC. The difference circumferences over the distance across the track between the two contact points forms a truncated cone. Solve for the distance from one of those contact points to the point of the cone will yield the radius. When the wheel on the outer rail is as tight as it can be against the rail, that's the shortest radius / maximum curvature which the wheel can traverse without slipping, Any curve sharper than that will have a path that's inconsistent with the circumference of one wheel or the other, and will create a slipping condition.
- PDN.
tree68 Euclid I thought the wheel taper was supposed to compensate for the difference in distance traveled as a train rounds a curve. To a point. For most mainline curves that will work. On a tight, slow curve, not so much. We regularly get squeal on our 5.5 degree curves at 25 mph. I don't know what the transfers/wyes at Deshler are.
Euclid I thought the wheel taper was supposed to compensate for the difference in distance traveled as a train rounds a curve.
Since the Wye's are 10 MPH, I would guess the curves that create them would be on the order of 10 or 12 degrees or more. Mudchicken or Paul North would know better than I would.
Yes, I can see how the taper compensation could only work in a certain range of speed and sharpness of curve. I have seen slow tight curves in yards and junctions where the trains are pulled hard and want to stringline, so the flanges on the inner rail are up tight against the inner rail. Then apparently, the inner wheels turn slower than the passage of rail would call for under outer rail. This badly mushrooms the rail head of the outer rail, creating a huge burr off of the rail head, nearly doubling its width.
BaltACD tree68 Euclid I thought the wheel taper was supposed to compensate for the difference in distance traveled as a train rounds a curve. To a point. For most mainline curves that will work. On a tight, slow curve, not so much. We regularly get squeal on our 5.5 degree curves at 25 mph. I don't know what the transfers/wyes at Deshler are. Since the Wye's are 10 MPH, I would guess the curves that create them would be on the order of 10 or 12 degrees or more. Mudchicken or Paul North would know better than I would.
Ideally, you work towards the same degree of curve as the equivillent curve in the turnout, but that never happens.
....and who is maintaining the wheel taper (maybe when new?)
Euclid Yes, I can see how the taper compensation could only work in a certain range of speed and sharpness of curve. I have seen slow tight curves in yards and junctions where the trains are pulled hard and want to stringline, so the flanges on the outer rail are up tight against the outer rail.
Yes, I can see how the taper compensation could only work in a certain range of speed and sharpness of curve. I have seen slow tight curves in yards and junctions where the trains are pulled hard and want to stringline, so the flanges on the outer rail are up tight against the outer rail.
Logic says that in a stringline situation, the flanges would be tight against the inner rail. A train moving with enough speed might force the flanges against the outer rail, due to centrifugal force.
EuclidThen apparently, the inner wheels turn slower than the passage of rail would call for. This badly mushrooms the rail head of the inner rail, creating a huge burr off of the rail head, nearly doubling its width.
AFAIK, the rails at Deshler haven't been swapped for several years, and I haven't noticed any indication of the mushrooming you mention during my visits there.
Which wheel would slip would be a function of the center of gravity of the car. If the curve is canted, and the speed is slow, that will be the inner rail. The outer wheel will slip.
There are probably 15 trains each on the SE and SW transfers per day at Deshler.
If there's enough speed to throw the center of gravity toward the outside of the curve, then the inner wheel would likely slip.
28 stone rail grinders - only really have been in play for the last 25-30 years.
Euclid... the proper terms are shelling and spaulling.
mudchicken28 stone rail grinders - only really have been in play for the last 25-30 years.
As have 286K and 315K weights, and various kinds of head-hardened rail, that make repeated 'maintenance' grinding workable and 'cost-justified'. Euclid might enjoy reading up on the theory of 'magic wear rate' and the assumptions involved in it.
The 'flip side' of rail grinding is the practical use of underfloor lathes for reprofiling wheels on a regular basis, which is much more of a 'thing' than it used to be.
He will probably find more references if he spells the latter 'spalling' as in discussions of gear teeth or bearings. The mushrooming requires axle load high enough that the rail steel under the work-hardened surface 'cold flows' under the combination of vertical and lateral load (this is a more common problem than it 'should' be in assuring 'hard coating' integrity in actual service) and as MC indicates it is better addressed with periodic grinding than 'lighter loads' or different operation, although it could be argued that lower weight on contact patches -- which BTW should be characteristic of commuter equipment not fully loaded, which would often be the case to observers -- would produce perhaps dramatically lower wear or distortion.
There are further considerations regarding braking forces, and the whole phenomenon of gauge-corner cracking that would have such implications at Hatfield in the UK.
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As Larry pointed out, I had inner and outer reversed in my above post, so I have edited that. In any case, I don’t think this is shelling or spalling. It appears that a lot of the rail head has been cold worked into a massive burr that hangs off rail head to the outside of the curve. It does not look like wheelslip rail burn, since it is quite consistent throughout the curve. The burr overhangs the side of the rail head by an inch or more, and effectively widens the rail head top surface to maybe 3.5”-4”. Although, in the burr area, the surface is rather organic in form.
mvlandswThe gage side of the outer railhead was noticeably worn while the inner rail gage side was not worn at all.
Thereby explaining why, in the days of "stick" rail, many roads swapped north and south rails to extend rail life.
I can imagine a giant machine that would do this with welded rail but I doubt it would be practical.
ChuckAllen, TX
cefinkjr mvlandsw The gage side of the outer railhead was noticeably worn while the inner rail gage side was not worn at all. Thereby explaining why, in the days of "stick" rail, many roads swapped north and south rails to extend rail life. I can imagine a giant machine that would do this with welded rail but I doubt it would be practical.
mvlandsw The gage side of the outer railhead was noticeably worn while the inner rail gage side was not worn at all.
On CSX it is done with the Curve Patch rail gangs. The high rail used at one location may have been the low rail at another location. Rail is a valuable capital asset - carriers will use it as necessary to get their full economic value out of it.
Remember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location.
Only when rail is totally worn out will it be considered 'scrap'.
I thought the tapered wheel served as enough of a differential.
BaltACDRemember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location.
In some cases it also got cascaded down to secondary lines. Some of the rail on the old NYC Adirondack Division dates to the 1920's.
A while back I was waiting for an Operation Lifesaver train to pass on the Montreal Sub when I noticed that at least some of the CWR there was originally stick rail. The bolt holes were still there...
tree68 BaltACD Remember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location. In some cases it also got cascaded down to secondary lines. Some of the rail on the old NYC Adirondack Division dates to the 1920's. A while back I was waiting for an Operation Lifesaver train to pass on the Montreal Sub when I noticed that at least some of the CWR there was originally stick rail. The bolt holes were still there...
BaltACD Remember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location.
mvlandsw tree68 BaltACD Remember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location. In some cases it also got cascaded down to secondary lines. Some of the rail on the old NYC Adirondack Division dates to the 1920's. A while back I was waiting for an Operation Lifesaver train to pass on the Montreal Sub when I noticed that at least some of the CWR there was originally stick rail. The bolt holes were still there... Chessie System moved some of it into yards. You had to be careful when kicking cars. They would roll alot farther on the welded rail.
Chessie System moved some of it into yards. You had to be careful when kicking cars. They would roll alot farther on the welded rail.
Especially if a Tie and Surfacing gang had worked over the track after the installation of welded rail and leveled off the all the mud holes that had been created by the joints in the stick rail.
BaltACD cefinkjr mvlandsw The gage side of the outer railhead was noticeably worn while the inner rail gage side was not worn at all. Thereby explaining why, in the days of "stick" rail, many roads swapped north and south rails to extend rail life. I can imagine a giant machine that would do this with welded rail but I doubt it would be practical. On CSX it is done with the Curve Patch rail gangs. The high rail used at one location may have been the low rail at another location. Rail is a valuable capital asset - carriers will use it as necessary to get their full economic value out of it. Remember as the carriers removed stick rail from the main tracks, they loaded it up on rail trains and moved it to their rail plants where it was cropped and welded and sent back out for installation at some other location. Only when rail is totally worn out will it be considered 'scrap'.
The Class 1 I work for does not reuse or transpose curve-worn rail and hasn't for quite a while. The reason is that you sometimes have to cut a plug rail into the middle of the welded rail (e.g. to remove a rail defect). In order to weld the plug rail into the existing "parent rail", the cross-sections of each rail have to approximately match each other. Local maintenance forces have to keep a variety of different size rails with different amounts of head wear and gauge face wear, to use as plugs in the various kinds of parent rail on their territory. If you start tansposing curve-worn rail, now your plug also has to be able to match the field-face wear as well, and the problem of getting good matches becomes significantly harder. (You would also need extra varieties of "compromise" thermite weld kits, which turn a "pretty good" match into a "good enough to weld together" match.)
More generally, the economics of second-hand rail are not as attractive as you might think, even for tangent rail that doesn't have funny wear patterns. The cost to weld, transport and install rail is pretty significant. If you're going to pay all those costs, you want to install new, clean rail that will last as long as possible.
There is definitely a market for second-hand rail, but as you say, it is on lightly used yard and industry tracks, where even rail that's almost all used up will last forever just due to the lack of tonnage. Even there I don't believe people are generally reusing curve-worn rail anymore.
Until a few years ago we would pick up and recondition some welded rail (from tangent track) and make it available to certain types of maintenance and construction projects. I always believed that there was a built-in accounting bias that made SH seem more attractive than it actually was. New rail would have to be purchased - a capital expense, competing with other priorities for capital funding - while SH rail, which was already fully depreciated, was available to your project for just the cost of the reconditioning. The opportunity cost of not selling that rail into the scrap or SH markets was never accounted for.
I don't think that was what caused us to stop using it, however; it was more the cost, safety risk, and operational difficulty of getting welded rail picked up and sent back to the welding plants for reconditioning. Now there's a rail pick-up contractor who runs along at the back of the rail gang, chopping the old rail whatever lengths he wants and stockpiling it for later loading onto trucks and / or flat cars. If the roadmaster wants to keep some of it to make into plug rails, he has to reserve it ahead of time and make sure the contractor doesn't take it.
Dan
During the final years of my career CSX was having Sperry rail detection make 4 passes a year on the Main Line Routes - additionally the rail grinder was making yearly appearances. With that level of inspection and care the condition of curve worn rail was a known commodity before it was ever relaid. Rail segments with bad sections were marked and got returned to the rail plant for remediation.
The CSX Engineering Department keeps highly detailed records of all rail on the property. They know what they are picking up and what they are laying down.
Dan, thanks for that informative post with those insights, some of which I haven't seen before.
dpeltierI don't think that was what caused us to stop using it, however; it was more the cost, safety risk, and operational difficulty of getting welded rail picked up and sent back to the welding plants for reconditioning. Now there's a rail pick-up contractor who runs along at the back of the rail gang, chopping the old rail whatever lengths he wants and stockpiling it for later loading onto trucks and / or flat cars. If the roadmaster wants to keep some of it to make into plug rails, he has to reserve it ahead of time and make sure the contractor doesn't take it. Dan
Sounds more like a PSR ploy. Turn 'worn out' capital assets into cash from scrap sooner than later. Shareholder value you know.
have heard the screech many times, usually on flat surface, and always thought it was maybe brakes dragging. Used to hear it a lot waiting on our Metrolink platform right next to UP or BNSF tracks.
BaltACD dpeltier I don't think that was what caused us to stop using it, however; it was more the cost, safety risk, and operational difficulty of getting welded rail picked up and sent back to the welding plants for reconditioning. Now there's a rail pick-up contractor who runs along at the back of the rail gang, chopping the old rail whatever lengths he wants and stockpiling it for later loading onto trucks and / or flat cars. If the roadmaster wants to keep some of it to make into plug rails, he has to reserve it ahead of time and make sure the contractor doesn't take it. Dan Sounds more like a PSR ploy. Turn 'worn out' capital assets into cash from scrap sooner than later. Shareholder value you know.
dpeltier I don't think that was what caused us to stop using it, however; it was more the cost, safety risk, and operational difficulty of getting welded rail picked up and sent back to the welding plants for reconditioning. Now there's a rail pick-up contractor who runs along at the back of the rail gang, chopping the old rail whatever lengths he wants and stockpiling it for later loading onto trucks and / or flat cars. If the roadmaster wants to keep some of it to make into plug rails, he has to reserve it ahead of time and make sure the contractor doesn't take it. Dan
I guess you can read about it for yourself if you're interested:
https://www.arema.org/files/library/2016_Conference_Proceedings/Development_and_Execution_of_a_Comprehensive_Second_Hand_Rail_Removal_and_Sale_Program_at_BNSF.pdf
Note near the end it mentions that we had accumulated 7 MILLION feet of rail (over 1,300 miles) that had failed to get picked up in previous years. It was just sitting in the ballast all over the system. Aside from the monetary value, that's a lot of tripping hazards and potential disasters for ballast regulators, snow plows, and Jordan spreaders.
As an assistant roadmaster I filled in for a vacationing rail pickup train supervisor once. For every string you had to torch holes in the end so you could grab hold of it, then pick it up and sneak the train in under it. Any little problem and the string would start to buckle - yell on the radio and hope they stop the train moving before it kicks out and kills someone. You needed track and time for your train plus protection on any adjacent track (because you need guys on the ground to get it fed in), and there was absolutely nothing out there that had lower priority than you. Then at the end of the day you filled out a report explaining why you didn't make goal for the day.
And back at the plant a lot of what you picked up was so shot that it got scrapped anyways.
I don't know if any railroads still operate this way, but I think it was the right decision for us.
2016 was pre-PSR for U.S. Class 1's, and BNSF wasn't a PSR road then (or now).
The problem is, if the rail is completely worn out, then there's no compelling economic reason to incur a lot of expense to pick it up quickly. It's less costly to just leave it there and accumulate, until you get what Dan describes above.
And after the rail train picks it up as Dan describes above, it still needs to be unloaded someplace and cut into shorter pieces. Add all that up and it still pays to pick up the rail, but not by much, and might be even less than the desired OR number. Add in the opportunity cost of track time 'lost' to the pick-up train, and the value of the rail might even be negative.
Eventually somebody will cut it up into 18" - 24" 'crops'. Not particularly favored by electric arc steel furnaces because they stay jumbled with a lot of air and don't pack neatly, so it takes longer for the current to melt them (as opposed to tie plates and other small scrap, which packs tighter).
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