How did the rail business evolve, that there were/are so many differing weights and profiles of rail used out there?
As best I can understand your question:
In the early days, once they moved away from strap rail, the rail profiles were a function of the rolling process available at the time. As the rolling techniques improved, the common profile, used even today, is the T-rail, which gives the best strength and workable profile with economy of the material. The different sizes, usually referd to as the rail weight, started with the smaller rails and got larger to handle heavier cars and locomotives as the rolling stock technology allowed for larger and heavier loads. Today, traffic levels also determine the weight of rail used, lighter traffic areas will receive lighter rail because it’s cheaper. High traffic areas will get the heavier rail because the cost of replacing the rail more often (both money and loss of track use costs) exceeds the cost difference of the lighter compared to heavier rail.
Simple economy and open market place. Why use heavy rail on an industry track that gets a couple of cars a week? Likewise one can’t use light rail on a high speed, high volume mainline. Through time as railcars weighed more the rail had to get heavier to handle them. Same thing for the profiles. Companies (rail vendors) trying to get the most strength in a rail (marketing) using the least amount of material (aka least cost - greater profit). Then as materials improved, the profiles could change to take advantage of it.
OK, I am going to throw a curve ball into this thread. What’s the deal with so-called head-free rail? I am aware that SP used it extensively, and it’s the rail that’s used on 99% of the Phoenix line, but why that and what are the pros and cons to using it?
For others, head-free rail has a head profile that’s different than standard rail - it tapers inward toward the web from about 1" below the wheel surface vs. the conventional design which most people are familiar with.
Because it saved a significant amount of money. If in every foot of track, you save 4 lbs of steel (115 AREA vs 113 HF), you’re saving almost 2% of the cost of the rail. Rail is a signficant cost item for a railway company.
The theory behind the the HF section is that the area where the metal was eliminated was “meat” that wasn’t needed – the rail would be scrapped before the head was worn down to the point where the taper in the sides of the head began. That is more or less a valid idea in tangent track or on low-side curve rail, but on high-side curve rail it’s not a great idea. High-side rail can wear quickly enough on the gauge corner that pretty soon the rail is worn into the area of the taper, which means the gauge is now a little wider than it used to be. Because the high-side rail is already trying to creep outward under dynamic load as well as tipping outward as the inside spikes pull out and the outside edges of the plates cut the ties, the track can get itself into a serious wide-gauge condition very quickly. (Curves can often be wide-gauge dynamically but within gauge statically.)
SP did just about everything a little differently than everyone else. They had some very different ideas on tunnels and wayside signaling.
RWM
The short answer is “because it could.” Rail sections proliferated because:
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There was not a lot of experience with what was best
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Metallurgical science was naive and sections offered potential solutions for the problems encountered in use.
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Because metallurgical science was naive, many mills could economically participate in the manufacture of rail and different sections enabled them to differentiate their offerings
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Rail company ownership was highly fractured enabling many different viewpoints
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Rail was an extraordinary proportion of the cost of the railway until the post WWII period – more than 50% of the total cost of building and equipping a railway built in the 1860-1870 period went into the rail alone! – thus there was tremendous incentive to try and find ways to accomplish the same task with lower cost of rail.
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Without experience, without metallurgical science that could determine what worked, what didn’t, and why, there was ample incentive to experiment with sections on a broad scale.
As metallurgical science matured, variety of sections declined:
- The demands of the metallurgy forced mills that could not make the technological improvements out of the business – from dozens of mills to today’s three U.S. mills. Any idiot could roll rail in 1880; today only the very serious with very deep pockets can afford to play in that game.
- Rail company consolidation created a consensus all of its own.
- Experience proved that many of the alternative sections were quite inferior (Dudley, for example).
- Experiences sorted out which of the were economically inferior.
- Mechanization and higher labor costs made it more expensive to retain non-standard sections – standardization makes for lower labo
I’ve wondered why “head-free” was also called gauge-free - thanks for the enlightenment.
- Erik
SP being SP, perhaps its head free rail came about by the head being worn off and SP kept using the rail.[:D]
Evolution. Evolution of the railroad, its cars and locomotives and plant. Evolution of the steel industry, its metalurgy and processing. Evolution of engineering for both. Thus standards were set and evolved as time and needs changed. So, there may be yards or sidings, even whole branches, which see very little use so have not been upgraded (new rail) in decades while high density lines with heavy loads or frequent traffic get newest technology almost instantly.
I have hunted for what the original track was like ever since my late grandmother told me, when I was a teenager some 40 years ago, that the original track was strap iron laid on wood. What was that, I wondered? Well, recently I was reading some history she wrote about her grandfather, William Balum Thompson, who won a contract from the Georgia Railroad to build roadbed and track from Union Point to Greensboro, that the straps were 3/4 inch thick and 3.5 inches wide. They were laid on 9 inch square sills which were then laid on ties spaced six feet apart. No mention of the type of wood was made, but I’d guess oak since it was so prevalent in Georgia. Now if I could find out what an average loaded freight car and coaches weighed that got to use that track. Maybe Atlas will come out with a vintage track for models of the original locomotives. Jock Ellis
I believe there is an example of the track you describe at the Rail Park at Rochelle, just visible in the cam view.
Building scale strap rail track would certainly be a challenge - particularly with regard to getting electricity to the locomotive. Perhaps circuit board stock could be used for the rails. But that’s a topic for the MR forums. Maybe somebody has already done it.
Different profiles and weights from a variety of sources, makes sense. At what point did conformity become a factor in the purchase of rails?
Let’s say you strung together a bunch of lines end to end, like the NYC. Would you be dealing with rail from 10(?) different sources, of 10 different weights, profiles and quality standards?
Is a different weight or profile of rail used in a turn, than what is used on a straight run of track?
About 150 years ago. (No kidding.) But things take time to happen.
More like 100.
For example, on a Class 1 today, you might find 75, 80, 85, 90, 100, 105, 110, 112, 113, 115, 127, 131, 132, 133, 136, 141lb. sections.
RWM
Very often. For example, a line might have 115 stick rail in the tangents, and 136 CWR in the curves, where the 115 all wore out years ago. Or it might have 136 control-cooled CWR in the tangents, and 141 ultra-premium in the curves.
RWM
My experience was that the weight and profile would be the same, but in the sharper curves premium rail was used. Premium rail (often called “chrome rail” ca1980 on CPR) had a slightly different mix of trace alloys in the steel, which made the rail more durable and last longer. Premium rail came with a premium price, of course, so it was only used where the economics justified it. An area with lots of curves where the rail wore out quickly might be first to get a heavier section during a rail program, part of modernization, with still usable rail from tangent sections saved for relay elsewhere. I never came across a case of routine switching rail sections from tangent to curves. CWR (welded rail) is the preferred way to go, so you don’t want to be inserting lots of compromise joints. But I guess it also depends on how desparate for money the railroad is.
The incremental step from 132# rail to 136# rail was due to a redesigned head. Making it thicker allowed an additional 4 pounds per yard to be worn off the top surface by rail traffic and grinding programs, before the rail needed to be replaced. The base and web were unchanged.
John
John – good info on CPR. Go look at D&RGW some time. A very rich railway that was “rail poor” due to peculiarities of its CEOs, to the frustration of its engineering department. The principle main lines varied with 110, 112, 113, 115, 131, 133 and 136, and through a terminal with slow speeds on the main track there was sometimes 100. A pattern of 112, 113, and 115 on tangents, and 131, 133, or 136 on curves, making for a mix of 5-1/2" base on tangents and 6" base on curves, became the pattern in the 1940s and persisted until the late 1970s, when 136 finally become standard. Not until the 1980s did D&RGW agree that CWR was a good idea in heavy curves, so one can find heavy curves laid with 136 stick rail in the 1970s. On the Tennessee Pass line it’s almost all 115 stick dating to the 1950s on tangents on the main line, and sometimes it will be right next to 2nd hand 136 CWR on the sidings!
SP was much the same – rail sections varied wildly, but in its case due to poverty. I was out on a former SP line the other day that UP has not yet done much rail work to as traffic has not been particularly heavy, and there was not even consistency between 5-1/2" and 6" base between one side and the other on curves. Plus the HF sections thrown into the mix.
RWM
Part of the different sections might have been to reduce pilfering.
As I recall a story…
One time the Soo piled up some cars on MILW trackage, somewhere between Rugby and Milwaukee. The Soo section came out to help fix things up, but they used 9040 rail, and the MILW used 9020, or something like that. The rail wouldn’t fit the tie plates, etc. They had to get some MILW materials to get anything done.
There is also a fair amount of the old Pennsy 155# around in some of the ex-Conrail areas. Also 70# and even some 65# on the odd industrial or yard track. Also a number of the weights have different origins and profiles. For example 90# comes in at least 10 flavors, and 100# in 11.
LC
(And then you have the wierdness of 155 step welded to 90 near a crossing frog, should have stepped down for some reason but wasn’t)
…and then you have all those variations in bolthole spacing, number of holes (4-8 holes) in the angle-bar plus bolt sizing…[%-)][%-)][%-)]…apples and oranges bigtime!