ALL NEW RAILS TO BE USED IN LAYING NEW TRACKS COME ON A FLAT CAR IN STRAIGHT LENGHTS. MY QUESTION IS THIS. HOW DO THEY GO ABOUT BENDING THE STRAIGHT RAILS TO CONFIRM TO THE RADIUS REQUIRED?
THANK YOU,
ERNIE
The same way they install it; with a big machine.
Rail is more flexible than you think.
Dave
Lackawanna Route of the Phoebe Snow
Phoebe Vet is right, I remember seeing a picture in TRAINS of a welded rail train pulled by an NP Challenger snaking its way through a pair of crossovers with little apparent difficulty.
I always thought that rail had to be bent during manufacture to fit the curve to be constructed. Then I had to opportunity to help (ha, I was more 'in the way', than 'help') lay track for a local "historical village" here. The fellows that were doing it used a tractor with a scoop on the front to just plow out a section of the ground; about a 100 ft. straight section in front of the depot building and then a gentle curve for a another couple hundred feet. There was a big pile of donated rail and ties to one side and I wondered how they were going to find rail to fit the curve they had just layed out, since they didn't seem to be paying much attention to what was in the "stock pile" and what they had scooped out as a ROW.
Then they began to put ties down on the ground and they just spaced them by eye and again kind of followed the curve they had plowed out. Again, not looking at the rail in the pile to see if they had some that would "fit the curve".
I found it very confusing!
Finally it came time to put rail down and they wrapped a chain around one stick and pulled it out of the pile with the tractor, It appeared they had picked a nice straight piece and it was drug to the straight section of the ROW and some holes were drilled in the ties and a jack hammer was used to shove spikes around the foot to hold it down.
Then another stick of rail was drug to the end of the first one and kind of aligned with it so some bars ("fish plates"?) could be bolted between them to hold them end-to-end, and then another rail to the end of the 2nd one.
That was when I noticed that these three sticks of rail were no longer following the curve of the ROW they had plowed out. It wasn't far off, but I thought, "Ha ha, this will be good!" While I was trying to tighten the bolts to connect the two pieces together, one of the fellows walked to the other end and just kind of kicked at it to get it to bend to fit in the right place.
The next piece was getting to the place where the ROW began to take on a much sharper curve and I figured it would take the tractor to pull the rails into place instead of just kicking at it. But, although they no longer could just kick at it (or maybe his toes were hurting), all it took was to grab the end by hand and give it a good pull.
It was not as easy to bend as a wet noodle, but it was not difficult to get it to conform to a gentle curve.
I have to admit that I am still amazed that a "Rail Train" can carry a couple dozen 1/4 mile long rails in a train and get them ALL to bend as the train snakes around all the curves to where they will be layed!
Semper Vaporo
Pkgs.
The only rail that gets bent for service is the bent stockrail in a switch or streeetcar rail with a radius sharper than 30 degrees (R=193.19) which a regular freight locomotive or railcar couldn't handle anyhow. The bent stockrail uses a fulcrum jack & heat and the streetcar track uses a series of at least three rollers and heat.
Union Pacific has had a rail/tie replacement train all up and down Donner Pass this last month. They just finished up over the weekend. It's quite the operation to watch as the front of the train is on old rail and tie and the rear is on new rail and tie.
Related, I caught an empty MOW Continuous Welded Rail train at Cape Horn on Sunday. No rails on the train, but imagine such a loaded train snaking through the curves and elevations of Donner.
A couple of links that might interest some around here.
Particularly, in this day and time of automated track maintenance work gangs. Track maintenance has always been part of the scene, but as expenses rose the man has been supplemented by machines to speed work production.
Up until the 1960's most of the labor was manual, and Track Gangs were much larger than currently used. They were called "Gandy Dancers'; Gandy being a major manufacturer of the specialized tools they used. Many people not think that the singing they do is an embellishment for entertainment, but it was actually purposeful in that it coordinated movements of large groups of men who were engaged in placing track, lining track and adjusting curves, as well as driving spikes while laying rail as a coordinated activity.
Back in the first half of the 20th Century, many County Prisons and State facilities were able to rent out groups of inmates as labor gangs when work for local political entities was in short supply. In mates were hired out to railroads, and farms, and construction. Anywhere there was a need for heavy manual labor. Railroad MOW activities were always heavy on manual labor and work was done regardless of the weather.
Film from 1973, about 3 minutes into this shows a Clinchfield RR MOW Track Gang working laying track and spiking it down:
http://www.youtube.com/watch?v=3r_cI3kYYhM&feature=related
This one has some Track lining manually:
http://www.youtube.com/watch?v=025QQwTwzdU&feature=relmfu
This following link shows some CWR Rail on cars and tells how it is handled for application:
http://www.wsorrailroad.com/projects/projects03.html
For tight bends there is a rail bending tool. This would only be used on tight industrial track.
http://www.aldonco.com/catalog_category.asp?sec=3&cat=77&subid=77
For normal stick rail, a Pettibone swing loader can be used to pull the rail over.
http://www.gopettibone.com/speed-swing/
A modern articulated front end loader will do the same thing.
Long aligning bars and a crew of men will do the same thing.
Welded rail is usually bent into the curve by the machine that pulls it into place.
The rail is far less stiff in the horizontal direction than the vertical, due to it's I or T shape - less metal at the far edges.
Mathematically, the stiffness of the rail is inversely proportional to the total connected length of the pieces - i.e., 1 / L. intuitively, the longer it is, the more length of a lever you have at the far end to induce a bend at the near end.
More later . . .
- Paul North.
PDN, MC,
The dirty feathered guy sort of implied that for anything broader than 30 degrees the rail is still within its elastic limit (i.e. will return to straight if removed from the track). I'm wondering if I'm offbase in making this assumption? (note that most people who know think I'm offbase most of the time...) It may b the elastic limit is reached at less than 30 degrees of curvature and/or depend on the weight of the rail.
- Erik
Darn good and insightful (not inciteful ! ) question. I see 2 ways to analyze it: 1) strain; and, 2) stress.
1. Strain: Assume a rail with a base - the outside edge of it is where the most bending will occur - that is 5" wide (representative value for smaller / lighter weight rails typical of such sharp curve installations), hence it is 2.5" from the vertical axis/ C-L of the rail = 0.208 ft. Assume that the elastic limit = yield point is at a strain of 0.1% of the length (i.e., 0.1 inch in a 100 inch = 8 ft. 4 in. length), which is common for many steels. By proportional circles/ radii, a curve with a radius of about 208 ft. (or less) = 27.82 degrees by the chord definition would exceed that limit. Similarly, for a modern or larger rail with a 6" wide base, the limit would be a 250 ft. radius (23.1 deg.) curve. So yes - "It depends" - but MC's statement and your assumption are essentially valid, and not far off at worst.
2. Stress: I've got to compute the I-yy (Second or Area Moment of Inertia) about the vertical or y-y axis of a rail to get an essential value to complete that calculation. Somewhat surprisingly, I'm having a tough time finding one anyplace, so I'll have to figure it out on my own, I suppose - which is OK, because I'm curious enough about this to want to look into it a little further. But that may take a day or two, so just call it "Pending" in the meantime.
None of the above includes the Y-shaped girder rail or other asymmetric or unusual shapes, because they are much stiffer on one side than the other.
Coincidentally, just last weekend I scanned in a couple photos of this taken to an extreme, and this is now the perfect opportunity to post them. Again, give me a day or so . . . stay tuned . . .
Overall View of Boeing Vertol's "Zig -Zag Test Track" for its Light Rail Vehicles - Fall 1977 (not my photo):
Detail View of 45 ft. Radius Curve (Chord Degree of Curvature = Undefined ! - yes, those rails had to be bent/ pre-curved) and Vertical Curve Replicating 15th Ave. & Taraval Street Intersection in San Francisco - N 37.74324 W 122.47136 (also not my photo):
More later.
Paul,
Those are some neat pictures you posted there! Seems I incited you to do some serious posting. The duplication of the 15th & Taraval trackwork must have been a bit of a challenge.
While I am a double-E by trade (with a bit of NE thrown in), I still remember the Intro to Materials Science class from the F73 quarter. It did take me a while for the difference between elastic modulus and yield strength to fully set in and a bit longer to grok moment of inertia. A very useful course and Cal's College of Engineering was wise in making it a requirement for all but the Cmp Sci crowd.
I'd also be curious if a curved rail would take any set after a few hundred million gross tons passed over it with the corresponding work hardening.
Thanks again for the replies!
I had the opportunity to witness the removal of the rail yard in Las Vegas and the relay of the tracks leading to the new refueling area. As the new rail was lifted by the crane for installation, it bent like wet spaghetti and sagged to the ground about about 60 or so feet from the tongs. Transversly -- I.E. side to sidet but not up and down, the rail is remarkably flexible and would not need to be bent for any normal curve. I believe it was 136 lb rail too, so it wasn't small stuff.
Paul_D_North_Jr Darn good and insightful (not inciteful ! ) question. I see 2 ways to analyze it: 1) strain; and, 2) stress. 1. Strain: Assume a rail with a base - the outside edge of it is where the most bending will occur - that is 5" wide (representative value for smaller / lighter weight rails typical of such sharp curve installations), hence it is 2.5" from the vertical axis/ C-L of the rail = 0.208 ft. Assume that the elastic limit = yield point is at a strain of 0.1% of the length (i.e., 0.1 inch in a 100 inch = 8 ft. 4 in. length), which is common for many steels. By proportional circles/ radii, a curve with a radius of about 208 ft. (or less) = 27.82 degrees by the chord definition would exceed that limit. Similarly, for a modern or larger rail with a 6" wide base, the limit would be a 250 ft. radius (23.1 deg.) curve. So yes - "It depends" - but MC's statement and your assumption are essentially valid, and not far off at worst. 2. Stress: I've got to compute the I-yy (Second or Area Moment of Inertia) about the vertical or y-y axis of a rail to get an essential value to complete that calculation. Somewhat surprisingly, I'm having a tough time finding one anyplace, so I'll have to figure it out on my own, I suppose - which is OK, because I'm curious enough about this to want to look into it a little further. But that may take a day or two, so just call it "Pending" in the meantime. None of the above includes the Y-shaped girder rail or other asymmetric or unusual shapes, because they are much stiffer on one side than the other. Coincidentally, just last weekend I scanned in a couple photos of this taken to an extreme, and this is now the perfect opportunity to post them. Again, give me a day or so . . . stay tuned . . . - Paul North.
This sounds like the kind of problem they would have given us 30 minute or so to do in college, but would take me about 3 days now!
I would think you could do the strain calculation and use it to calculate the lateral forces generated by a a rail train. But, it made my head hurt just thinking about what I'd have to do to figure it out,,,,
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Paul_D_North_Jr - Paul North.
I SO WANT to take a pair of 6-axles down that!!!
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
Zug,
It would be even more fun taking a DD40 down that...
Very interesting stuff.
M C....What is different about streetcar trucks to allow them to negotiate sharp curves such as turning into a street requiring a 90 degree curve / turn...?
Do they have a shorter "wheelbase" on the trucks that allow them to do this without "climbing" up on and off the rail.....?
I used to look at the "turning loops" for the streetcars in Johnstown, Pa. and wonder how they could come around such a sharp turn.
By the way, that {Johnstown Traction Co.}, abandoned their streetcar operation in 1960 after decades of operation. After WWII they acquired single control ended PCC cars that required "turning".
Item: There are lots of photos on the internet of JTC operation, including photos of some of the "turning loops".
Quentin
Quentin,
It's not so much a matter of short wheelbase as it is provisions to let the truck swivel as much as it needs to negotiate a 35' radius curve. Two things come to mind in that regards, brake rigging and motor leads. Streetcars almost never had ventilating ducts for the motors, so that wasn't an issue. Do remember that the earliest streetcars were single truck designs and those almost always had wheelbases longer than what's found on the trucks of double truck streetcars. The early streetcars were rarely equipped to operate in multiple, those that were usually had radial daft gear to allow operation around the sharp curves.
I have a vague recollection that a 40' boxcar could negotiate something like a 40' radius curve if it was uncoupled. I do remember that the B&O Docksiders were designed to negotiate some pretty tight curves on the Baltimore docks, but i don't recall how tight those curves were.
HTH, Erik
B&O didn't only have to service the docks with tight radius turns - there were also areas where the B&O serviced industries from jobs that operated in the middle of streets. Two jobs in particular - the Mount Clare job that went on duty at Pratt & Poppleton Streets, near the B&O Museum and serviced customers on Pratt St. from the Museum down to President St - the longest lasting being supplying newsprint for the Baltimore News-American newspaper - the job used a GE 44 ton locomotive and could handle a maximum of 9 empty cars up the hill from the waterfront back to Mount Clare - if they had more than 9 cars for their nights work, they had to double the hill.
The other was the Key Highway Job that came out of Locust Point yard from a track at the Riverside Shop complex onto Key Highway. The job serviced the numerous ship repair and ship candler businesses on Key Highway, McCormick Spice company on Light Street and various piers that occupied the South side of Pratt Street and down to a interchange with the PRR at President Street. With more industries to service and a heavier work load this job used a SW-1. In the very early 1970's it was not unusual at 3 AM to view both jobs doing their work side by side on Pratt Street where the Harborplace Pavilions now stand. A different era of railroading.
erikem Quentin, . I have a vague recollection that a 40' boxcar could negotiate something like a 40' radius curve if it was uncoupled. I do remember that the B&O Docksiders were designed to negotiate some pretty tight curves on the Baltimore docks, but i don't recall how tight those curves were. HTH, Erik
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Never too old to have a happy childhood!
Thanks Erik.....Understand what you are saying about the cooling air ducts on streetcars...Never gave that a thought. Wonder how they got away without much cooling.
I realize those motors, usually didn't have a long extended load until going back to "off throttle" or "stop", during city street operation.
And as for the "older" single axle ones....That does gives one a thought how that worked. That would have required quite a bit of "sliding" of the wheels negotiating such tight curves, and not climb the rail.
Street cars do give out a bit of squealing sound like we do have parts rubbing together rather hard on those tight turns into another cross street.
BaltACD,
Thanks for the interesting history lesson about Baltimore.
I think you meant "single truck" not "single axle", though small single axle cars may be possible with Segway technology.
BTW, some modern streetcars have reduced squealing on curves by dispensing with the axle and allowing the wheels to rotate independently. The main impetus for this was allowing lower floors.
...Yes, Erik....that's exactly what I meant. Wasn't sure since the "car" had just 4 wheels {2} axles, wasn't sure if it was still a "truck".
And on squealing and just plain noise, such as loud banging at track joints, was dampened, with cars after the War having an "insulating" structure between wheel {tire} surface and hub.
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