jockellisI 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
You can find many modern examples of "strap rail". Just go to an amusement park. If they have a traditional wooden roller coaster, the track structure will almost always be strap rail. The main difference is that roller coaster rail has a "lip" (to keep the trains from flying off the track into the wild blue yonder on curves or at the tops of hills).
Railway Man Thanks for the outstanding description of C&NW practice and history, Kurt.
Thanks for the outstanding description of C&NW practice and history, Kurt.
Wow! Thanks for the compliment! High praise indeed from someone I regard as a real expert in the railroad biz.
Kurt Hayek
RAIL TALES:
I'd always been interested in rail; reading (and trying to make sense of) the mysterious information rolled on the web of rails I found in my teenage wanderings along railroad tracks in Minnesota. One of the things that was so baffling to me was that there didn't seem to be any consistency in the markings; for example, on the CNW (former CStPM&O) mainline through Mountain Lake, Minn. (my father's home town) there would be rail with 9035 markings, but there was also rail marked 90-OM. What did it mean? I gathered (from reading Trains, plus a railroad engineering textbook I'd inherited) that the 90 designated 90 lbs./yard, but what about the rest of the designation?
During college things became somewhat clearer; I became a student affiliate of the AREA (American Railway Engineering Association), also I was able to photocopy a CNW Twin Cities Division track chart belonging to a CNW locomotive engineer I'd become acquainted with. But, my real education began after I started working in the Twin Cities Division Assistant Division Manager-Engineering office in St. Paul (after graduating with a civil engineering degree plus a year working out west on the UP).
One happy discovery (among many for a railroad information junkie) was finding several charts listing dozens of rail sections, virtually every dimension associated with them, and (most important to me) a cross reference to various steel mill's designation for that rail section. That explained much: I found that a 90CNW rail section was identified as 9035 Illinois by U. S. Steel, but was designated 90-OM Lackawanna by Bethlehem Steel.
Another interesting discovery was a chart showing all rail sections used by the CNW in main line track, along with total miles of each rail section in track. This chart dated from the middle 1970s as I recall, and I think I still have a copy of it back in Minnesota. Since I can't refer to the chart I won't be able to give a numerical breakdown, but I still remember enough to give a overview that's probably more interesting anyway.
One point to remember it that this chart predated the installation of 136RE rail on the east-west main line; that started later in the 1970s when the North Western received federal 4R funding.
For the "traditional CNW System" (CNW plus CMO) there was a "Big Five" of rail sections (in very roughly equal proportions) of 115RE (11525), 112RE-M (11228), 100CNW (10035), 90CNW (9035), and 72 lb. (7201) rail. The designations in parentheses are USS-Illionois's; this is what we typically used on the CNW when referring to rail, and what I'll use to simplify typing.
The 11525 and 11228 sections were the workhorses on heavy-tonnage lines; both good rail sections, but they had suffered from years of deferred maintenance during the Heineman era and usually had become "end-bent" (the portion of the rail at the joint bars was bent down); once that happened it wasn't possible to obtain a smooth track surface anymore. But, in spite of that, once it was removed from track, sent to the rail welding plant at Tama, Iowa, and cropped and welded into CWR, we ended up with something pretty decent; the rail was nicely work-hardened, and it was control-cooled rail besides (and tested before going through the welding plant) so it held up well as CWR. There's still a lot of that CWR in service today, twenty years or more after it was laid.
The 10035 and 9035 sections were decent sections rolled during the teens and twenties; a lot of this rail had been laid new and was still in track, but a fair amount had been displaced by heavier rail, cropped to 31 foot sections (from the original 33 footers), and used as relay rail on secondary main lines. A major problem was that it wasn't control-cooled and was prone to develop internal transverse defects (TDs) that caused catastrophic rail failures. It was an experience running the Sperry car (rail tester) across lines laid with this rail (fortunately I wasn't involved); there would be so many defective rails to replace that the track forces couldn't keep up if the Sperry car kept testing. I guess they either stopped testing for a while or sent the car somewhere else.
The 7201 rail was an interesting case; one wouldn't think of anything this light as mainline rail but the North Western had lots of it, especially on the Western Division. Some notable lines with 7201 rail were Huron to Pierre, and Chadron to Rapid City; the latter handled a fair number of bentonite loads in 100 ton covered hoppers from Belle Fourche to Chadron. The rail actually held up fairly well; it was so flexible that it bent under load, while a heavier rail section would break instead. We even had 7201 CWR out there! By the way, I never was able to positively determine who developed this 72 lb. section but it seemed to be a Northern Pacific design from what I could gather.
Of course, there were other rail sections in use; some more notable being (going back in chronological order) 112RE (11225), 110RE (11025), 100RA-A (10020), 90RA-B (9030), 90AS(CE) (9040), and 80AS(CE) (8040) sections. And, there were the lightweights: 65 lb. and 60 lb. sections still in track on too many branch lines.
The 11225 section was another troublemaker; both it and the heavier 13125 design were AREA's replacements of the not-so-successful AREA 11025 and 13025 designs. Unfortunately, the initial 112 and 131 designs had problems, notably with a head radius that promoted excessive metal flow during initial service. Worse, in the long run, was that they predated control-cooling and were vulnerable to TD problems like the 10035 and 9035 sections. There was a long stretch of 11225 rail on the "Adams Line" between Butler (Milwaukee) and Wyeville that gave a co-worker (and railfan) in the Drafting Room considerable grief when he was working as Assistant Roadmaster in Adams; it was notorious for broken rails, especially in the winter.
The 11025 section was another pre-control-cooling design with the same TD problems, and not-so good design besides. At least the North Western didn't have a lot of it to contend with.
The 90RA-B section predated the 9035 design; it was an American Railway Association (hence the "RA") design. There were two "RA" sections for each rail weight: The "A" sections were taller, while the "B" sections were shorter with heavier heads; they were intended for use on curves and other severe head wear applications. During my time, the 9030 rail wasn't highly regarded; the consensus seemed to be that it was just a glorified 80 lb. rail, as the heights of 9030 and 8040 were almost the same. Indeed, more than once I'd find pieces of 9030 rail mixed in on a track with 8040 rail.
The 9040 and 8040 sections were both American Society of Civil Engineers designs; these ASCE designs dated to about the turn of the century and were the first attempts to standardize rail sections. The ASCE designs below 90 lb. were adopted by the AREA, and are still used today for rolling light-weight rails. For 90 lbs. and heavier rails the ASCE sections weren't too successful (so say my references, but without further explanation), and were supplanted by newer designs.
All the rail sections mentioned above (and some other besides) were used in side, yard, and industry tracks also, especially the more obsolete sections such as 8040 and 9030.
In 1960, the CNW purchased the railroad assets of the Minneapolis & St. Louis Railway; this added more rail variety to the mix. Primary rail sections on the Louie were 11525, 10025, 8531, and some 7040 on branch lines.
During its last few years the M&StL had been laying 11525 rail on portions of its Minneapolis to Peoria main line (good!), but the ultra-conservative Louie had used four-hole joint bars instead of the normal six-hole bars used with that rail section (bad!); negating in part the whole rationale for heavier rail (increased girder strength from taller and stiffer rail).
Otherwise, the Louie used 100RE (10025) for mainline rail; this is a decent section, and it was new enough to be control cooled.
The 8531 section is a PRR design; there was a lot of it on M&StL secondary lines, sidings and yard tracks. Too much of it was still sitting directly on the ties without benefit of tie plates, another Louie trademark!
In 1968 the North Western merged with the Chicago Great Western Railway; adding more 11525 rail, plus 90RA (9020), and 75AS (7540) sections.
At least the Great Western's 11525 rail had six-hole bars, but I seem to recall the bolt hole spacing was different.
The 9020 section was another of the RA sections mentioned earlier; this was the "tall" 90 lb. section and actually was a decent design, as suggested by AREA's adoption of it as their standard for 90 lb. rail.
I think the CGW also had some 85 lb. rail, but I'm not sure of that at this time.
The 7540 section was another ASCE design; CGW had a fair amount of it on branch lines and side tracks.
During the 1970s and 1980s the North Western abandoned thousands of miles of branch lines. Much of the rail from these lines was scrap, but there was quite a bit that was made into CWR and installed on state-funded branchline rehab projects. Some even went into secondary main lines. The whole process (cascading) resembled musical chairs: New 13637 rail generated 11525 and 11228 rail for CWR, this replaced 10035 rail (for example), which was then welded and replaced 9030 rail, this in turn was welded and replaced 65 lb. rail (scrapped).
There was 8531CWR, 9030CWR, 9020CWR, 9035CWR, 10035CWR, 10020CWR, 10025CWR, and 11025CWR, besides the mainline 11525 and 11228CWR.
Of course, the east-west line was getting new 13637 rail at the same time which generated a lot of good 11525 and 11228 rail for CWR; eventually there was enough so that non-control-cooled rail recovered was scrapped instead of used for CWR.
The acquisition of ex-RI lines in 1983 added more miles but not much more variety: 11525, 11228, and 9020 predominated, although there was lighter stuff on some of the Iowa branches.
On the Twin Cities Division we were right in the melting pot; most of the track was former Omaha (and after 1981 former CNW on the Winona-Huron line), but Cedar Lake and Railway Transfer Yards were ex-M&StL, and SE Mpls. and South St. Paul Yards were ex-CGW. Besides yards we had ex-M&StL and ex-CGW main lines to contend with also. Fortunately, unlike our roadmasters and track crews, I didn't have to keep this hodge-podge of track functioning!
We had plenty of HF rail when I worked MOW on the Frisco Rwy. Brian W. De Spain
10 would be a very, very conservative number....more likely nearing the 100's with the multiplicity of ownerships with each ownership having it's own ideas and financial realities to deal with. Remember each ownership ALWAYS believes it has the BEST idea to solve it's problems....without any knowledge of the problems that anyone else is experiencing.....at least back in the 19th Century. As things progressed into the 20th Century more information got passed amongst the carriers as well as the steel producers.
Never too old to have a happy childhood!
mudchicken Failed to mention here as well: (1) Design failures in mainline service like 110RE rail (the head wobbled under constant loading - causing the rail to be cascaded into the backtracks mui-pronto) (2) Why Accountants/Beancounters are never to be allowed to make engineering purchasing decisions:.....Santa Fe got stuck with miles of surplus oddball 101# Buffalo rail (lackawanna) as Korean War surplus over the Chief Engineer's objection because it was a "good deal" vs new 90# rail. (so much for standardization - its odd-size base was supposed to eliminate tie plates in rapid construction (it didn't) and was supposed to be interchangable with 90# rail (it wasn't - required special bars that FRA would not allow in US service)) Spread systemwide, there was little of it on any particular division and god-forbid you had turnouts made of the stuff.....
Failed to mention here as well:
(1) Design failures in mainline service like 110RE rail (the head wobbled under constant loading - causing the rail to be cascaded into the backtracks mui-pronto)
(2) Why Accountants/Beancounters are never to be allowed to make engineering purchasing decisions:.....Santa Fe got stuck with miles of surplus oddball 101# Buffalo rail (lackawanna) as Korean War surplus over the Chief Engineer's objection because it was a "good deal" vs new 90# rail. (so much for standardization - its odd-size base was supposed to eliminate tie plates in rapid construction (it didn't) and was supposed to be interchangable with 90# rail (it wasn't - required special bars that FRA would not allow in US service)) Spread systemwide, there was little of it on any particular division and god-forbid you had turnouts made of the stuff.....
Similar to all that awful Dudley section some of my former employers bought 2nd hand from Conrail.
In the words of one of my old division engineer friends, "When you buy second-hand rail, you're buying someone else's problem. There's a reason why they want to get rid of it."
RWM
mudchicken [snip] (2) Why Accountants/Beancounters are never to be allowed to make engineering purchasing decisions:.....Santa Fe got stuck with miles of surplus oddball 101# Buffalo rail (lackawanna) as Korean War surplus over the Chief Engineer's objection because it was a "good deal" vs new 90# rail. (so much for standardization - its odd-size base was supposed to eliminate tie plates in rapid construction (it didn't) and was supposed to be interchangable with 90# rail (it wasn't - required special bars that FRA would not allow in US service)) Spread systemwide, there was little of it on any particular division and god-forbid you had turnouts made of the stuff.....
Might that have been the 101 lb. DL&W = Delaware Lackawanna & Western section ? (Also branded as 101 DL and 10133). Even being in the area of that former road, I don't believe I've ever seen that particular section. Per this rail chart - http://www.akrailroad.com/tee-rail-sections-data - it appears to have had a 5-3/8" Width of Base BW - same as 100 RE - but which is nevertheless kind of oddball in a world that prefers rails with a Base Width of either 5", 5-1/2", or 6". And compared to those dimensions, that's not notably wider than normal, either, so as to be able to forgo using tie plates, like the 127 lb. Dudley (6-1/4" wide) or the 152/ 155 PS sections (6-3/4" wide) had. Then again, the 90 lb. ATSF section had a base 5-3/16" wide, which is even more oddball - no one was going to steal that rail and use it someplace else ! And the joint bar thing is weird - the FD Fishing Depth for the 101 DL is listed as 2-11/16" (2-3/4"), whereas for the 90 SF it is 3-5/32" (3-1/8") = about 3/8" more, which is a lot - so no, those joint bars would not have been compatible.
By the way - i've never seen anyone able to measure the actual Fishing Depth dimension in that location on a piece of rail that's still 'in track'. Instead, we measured vertically from the underside corner of the head down to the angled top of the base, and called that dimension the "Field Fishing" (credit to my former colleague Mark E. Kutz for coming up with that name). Crude, but a quick and effective way to figure out what you were looking at and what might fit it, when it was dark, wet, covered up with mud, coal dust, grain, etc.
- Paul North.
mudchicken (2) Why Accountants/Beancounters are never to be allowed to make engineering purchasing decisions:.....Santa Fe got stuck with miles of surplus oddball 101# Buffalo rail (lackawanna) as Korean War surplus over the Chief Engineer's objection because it was a "good deal" vs new 90# rail. (so much for standardization - its odd-size base was supposed to eliminate tie plates in rapid construction (it didn't) and was supposed to be interchangable with 90# rail (it wasn't - required special bars that FRA would not allow in US service)) Spread systemwide, there was little of it on any particular division and god-forbid you had turnouts made of the stuff.....
Ugh - seen some examples like that in my own line of work... Good engineering is knowing when to stop cutting corners.
I believe you were the one who used gauge-free to describe head-free rail.
- Erik
erikem Railway Man: 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.) I've wondered why "head-free" was also called gauge-free - thanks for the enlightenment. - Erik
Railway Man: 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.)
I've wondered why "head-free" was also called gauge-free - thanks for the enlightenment.
A couple of my photos of a slice* of 130 lb. AREA section, Head-Free Type 'A' rail, which around here was used mainly by the Reading RR and Central RR of New Jersey on their main lines. I believe this piece came from the Jersey Central line near Lebanon, Hunterdon County, NJ. Where it's tapered inwards at the lower corners of the head is where the metal was removed as compared to a standard T-rail cross -section (I should have marked an arrow on the paper that it's resting on to 'highlight' that detail - next time !). This piece has some head wear - notice that the upper left corner is worn down and rounded-off a little more than the opposite/ upper-right corner - so it was likely in tangent track only.
*Slice loaned for photos courtesy of W. W. Yoder, VP of W. E. Yoder, Inc., Railroad Track Contractor of Kutztown, PA.
When I find my Reading rail chart print I'll be able to tell you the dimensional details of the angles, and what the difference is between the Type 'A' and Type 'B' Head-Free sections . . . .
Murphy Siding How did the rail business evolve, that there were/are so many differing weights and profiles of rail used out there?
How did the rail business evolve, that there were/are so many differing weights and profiles of rail used out there?
Not mentioned so far: The personalities of the necessarily strong-willed Chief Engineers of the respective railroads, who were essentially kings of their own little empires. Specifically along the lines of "We'll have our own rail section - I won't use that other RR's rail section design (= also admitting that its Chief Engr. is smarter or better than me, or it might someday seem that way to my management) - mine is better anyway for X reason or detail", etc.
I heard this line of thinking in the mid-1970's from a couple guys who graduated from Penn State's civil engineering program in the late 1930's/ early 1940's, and then worked for the PRR as Track Supervisors (one of which included the Hudson River Tunnels), and then worked for a nationwide track contractor (T.F. Scholes, Inc., which went out of business in the late 1950's), so they would have actually known some of the personalities involved. I consider them to be reliable sources - this kind of thing wouldn't often be printed, but over drinks at the end of a long day on the road - yeah, I can believe it.
mudchicken (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!
(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!
Railway Man Murphy Siding Different profiles and weights from a variety of sources, makes sense. At what point did conformity become a factor in the purchase of rails? About 150 years ago. (No kidding.) But things take time to happen. 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? 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
Murphy Siding Different profiles and weights from a variety of sources, makes sense. At what point did conformity become a factor in the purchase of rails?
Different profiles and weights from a variety of sources, makes sense. At what point did conformity become a factor in the purchase of rails?
About 150 years ago. (No kidding.) But things take time to happen.
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?
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.
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
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.
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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.
Railway ManMurphy Siding Is a different weight or profile of rail used in a turn, than what is used on a straight run of track? 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
Murphy Siding Is a different weight or profile of rail used in a turn, than what is used on a straight run of track?
Is a different weight or profile of rail used in a turn, than what is used on a straight run of track?
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.
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
Thanks to Chris / CopCarSS for my avatar.
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.
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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.
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SP being SP, perhaps its head free rail came about by the head being worn off and SP kept using the rail.
"No soup for you!" - Yev Kassem (from Seinfeld)
Railway ManThe 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.)
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.)
The short answer is "because it could." Rail sections proliferated because:
As metallurgical science matured, variety of sections declined:
The advances in the last 20 years have been amazing, but it's very sophisticated. I can read the technical articles but I think you pretty much need a Ph.D. in metallurgy to understand anything beyond the abstract. But even if, for physical reasons, the metallurgy of 1900 was the best we could have ever have, we'd still have standardized on rail sections by now, because as labor costs go up, the economic incentive for standardization goes up, too.
silicon212OK, 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.
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.
SP did just about everything a little differently than everyone else. They had some very different ideas on tunnels and wayside signaling.
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