Target Profiles for Rail Grinding: A Never Ending Story
Jun. 24, 2024
Target Profiles for Rail Grinding: A Never Ending Story
By Anders Frick and Dr. Wolfgang Schoech &#; July,
For more Uic60 Railinformation, please contact us. We will provide professional answers.
Rail maintenance work is a process of removing metal from the rail head at the right time and at the right place. At first, rail grinding was performed to remove surface irregularities and defects &#; a process that required significant metal removal. During this curative process, the transverse rail profile was of secondary importance. Railways, today, have taken a preventive approach to rail maintenance &#; an approach in which thin layers of metal are removed at regular intervals and the transverse profile is kept within tight tolerances in order to optimize wheel-to-rail contact.
The question is: What is the best profile to be applied?
As rails are installed at different locations and as traffic characteristics change, one single profile cannot suit all conditions. Experience has shown that even new rail profiles, as-rolled and installed in track, do not provide ideal contact conditions for the wheels. Consequently, grinding worn rails to their original profile does not always improve wheel/rail contact conditions. Instead, a number of rail profiles have been developed to improve wheel/rail interaction and extend the life of rail.
In addition to supporting wheel loads, rail must also guide the vehicles. An effective contact geometry between wheel and rail is required to center wheelsets in tangent track and to promote curving through effective rolling radius difference in curves. Even when the contact geometry is good, however, conical wheel treads always create creep and resulting wear in the contact zone. The wheel tread tends to wear to a hollow shape while the rail profile tends to flatten, causing the contact geometry to deteriorate.
A variety of rail and wheel profiles have been developed over time in Europe, though standardization designed to ensure interoperability between different networks has reduced the number of wheel and rail profiles currently in use. The S wheel profile is now fairly standard, for example, as are the rail profiles standardized by UIC. Their geometry features a well-balanced compromise for average track situations and normal operational conditions in tangent track and curves.
&#;Profiling&#; in Grinding Practice
When rail grinding started roughly 50 years ago, corrugation removal was the primary task; the transverse profile was not considered to be of great importance. With the introduction of production tolerances for the longitudinal and transverse profiles, railways and their grinding contractors usually aimed to re-establish the profile of the various as-new rail profile designs that were in use.
As grinding practices showed that it was possible to produce individual railhead shapes within tight tolerances, new target profiles that were different from the as-rolled profiles were introduced. So long as a profile can be produced with the existing rail grinding equipment, the shape of the profile does not matter to the grinding contractor. Grinding technology, which applies the flat end of the rotating grinding wheels to the rail surface, provides an almost unlimited number of potential target profiles. Grinders are now equipped with systems that continuously measure the transverse profile to ensure that the specified tolerances are met, and the desired profile is achieved.
The German railways (DB AG) made the first attempt to reduce the number of target profiles for grinding in the late s. DB AG introduced a single target profile derived from the UIC 60 profile inclined at 1:40. This slightly more convex profile is now ground everywhere, regardless of the installed rail type, to ensure that all wheels run on profiles of the same shape (at least on lines that are regularly ground).
These ground profiles also overcome the effect of different rail inclinations (or cant), as some railways started and stayed with a 1:20 inclination while others changed to 1:40. The original UIC 60, now named 60E1, is inclined at 1:20; the modified German profile (60E2), now standardized, is inclined at 1:40. While the inclination varies for the two rail sections, the profiles provide virtually the same contact conditions. Changing from one profile to the other does not require a change in fastening systems, allowing rail grinding to be performed at much less cost.
In addition to being affected by wear, rail life is also affected by surface fatigue. Heavy loads and an increased number of loading cycles play an important role in fatigue, as does the size of the contact zone. Gauge corner fatigue, normally called headchecks, appears on the high rails of curves with big radii (see Figure 1). Sometimes they develop in tangent track, too.
Headcheck development is favored, when parameters, such as high axle loads, high train speeds, and high traction forces during acceleration and braking, are at work. In order to combat rolling contact fatigue (RCF), the gauge corner is systematically undercut and the top layer of rail steel that is showing signs of fatigue is removed.
Other railways have investigated the use of special profiles and have come up with similar solutions. The infrastructure company of Dutch Railways (ProRail) has developed a particular Anti-Headcheck-Profile with 1-mm gauge-corner relief, compared to the standard UIC 54 profile (see Figure 2 right).
French Railways (SNCF) have defined two new particular target profiles. An anti-headcheck &#;preventive&#; profile with limited gauge corner relief is applied where headchecks are not yet visible. A &#;corrective&#; profile with considerable gauge corner relief is ground where headchecks are clearly visible. Headchecks often cannot be completely removed, as the cracks are deeper than the prescribed metal to be removed (see Figure 2 left).
After an extensive test program, the German Railways incorporated a standard target profile, which permits only negative production tolerances (that are equal to moderate gauge-corner undercutting), into its grinding specifications.
Specific target profiles ensure that the equivalent conicity is kept within low limits in order to maintain vehicle stability at higher speeds. The German Railways introduced special gauge-widening profiles. The Austrian railways (ÖBB) developed a so-called &#;convex&#; rail head profile with a 22-mm gauge corner radius in order to combine the effects of low conicity and reduced surface fatigue development.
Wheel/rail interaction specialists can define ideal target profiles for grinding, knowing the feasibility of producing them within tight tolerances at low extra costs. The current focus is on the development of optimized target profiles for:
&#; Specific wheels (wear-adapted profiles).
&#; Fatigue reduction (anti-headcheck profiles).
&#; Running behavior (gauge-widening, equivalent-conicity profiles).
&#; Wear reduction (asymmetric profiles).
Profiles for Heavy Haul
Sweden&#;s 473-km &#;Malmbanan&#; heavy-haul line, which connects the city of Luleå on the Baltic Sea and the Norwegian city of Narvik, located on the Atlantic coast (see Figure 3), is characterized by small radius curves and steep gradients. The electrified line handles 30 million gross tonnes per year of mixed passenger and freight traffic, predominantly 30-tonne axle load iron ore cars. Temperatures on the line range from -40 ºC to +25 ºC. The resulting stresses in the rails vary from high tensile stresses during winter, increasing the risk of crack propagation and rail breakage, to compressive stresses in the summer.
Head checking, spalling and shelling defects were quite common in the s. Earlier these phenomena were considered &#;unavoidable,&#; and rails were frequently changed. Today, Banverket&#;s maintenance strategy on Malmbanan includes yearly maintenance grinding (including rail head re-profiling) and extensive rail lubrication in curves of less than 600 meter in radii.
When rail profiling was introduced (using a planing machine) in , asymmetric profiles were applied over distances of 200 meters in order to check their effect with regard to wear reduction. At about the same time, spalling and shelling started to appear on the gauge corner of the high rails. With that, the focus of rail profiling changed toward surface fatigue, and so-called &#;wear-adapted&#; profiles emerged. Tests continued using a grinding train, and &#;gauge-corner relief&#; became a leading principle in the continued development of grinding profiles.
These experiences led to the development of a profile that was more specifically adapted to the fairly hollow-worn wheels of the ore trains. In , a new (MB1) profile was developed. At first, this new profile was only ground in selected curves at the high rails, while the low rails and tangents still were ground to the standard BV50 profile (see Figure 4, left). In this profile design, the gauge corner area is much lower in order to accommodate the hollow worn wheels. The field corner side remains unchanged. The initial results showed reduced wear and delayed appearance of RCF defects.
A five-year grinding project was initiated on Malmbanan in . Test curves were ground once a year; profiles at 60 locations were selected for evaluation of the transverse profile. As the contact path of the MB1 profile is better adapted to the hollow-worn wheels, the amount of RCF defects, such as head-checking, spalling and shelling, decreased. But the old RCF defects could not be removed entirely by grinding. However, with the use of the MB1 profile, an unloading of the gauge corner was achieved, resulting in a decreased growth rate of existing RCF defects. In , the MB1 profile was introduced as the standard profile on all high rails, and the BV50 profile was restricted to the low rails and tangents.
Damage to a series of older rails made it necessary to develop a profile that could prevent emergency rail renewal. It was also determined that the MB1 profile was not the optimal profile in some curves, and the head-checks became too large before the following grinding program took place. Experience on other railways indicated that more pronounced gauge-corner grinding could reduce further wheel contact at the damaged contact zone on the rail.
Another profile (MB3) (see Figure 4, right) was developed to shift the contact band farther to the field side and thereby optimize gauge corner relief. The application of this profile had the desired effect and the rails could be kept longer in track. The MB1 profile is now standard on all rails (tangents, low and high rails in curves), except for specific, &#;problematic&#; high rails to which the MB3 profile is applied.
An economic evaluation of the heavy haul grinding program between and (shown in Figure 5) indicates that rail maintenance costs were significantly reduced after the introduction of the rail grinding program. The grinding program soon provided a &#;pay-back&#; in the reduced need for rail renewal.
Turnout Grinding
Rails in turnouts are ground for the same reasons as rails in open track. Switches at Malmbanan were first ground in . The results were encouraging, but it took some time to establish a strategic rail grinding policy for turnouts. Today, almost every switch on Malmbanan is ground every year (30 MGT). Initially, the target profile was the &#;standard&#; BV50 profile with an inclination of 1:30, instead of the installed vertical profile. However, as in open track, this standard profile resulted in unacceptable wear and the rapid occurrence of RCF defects. Consequently, another profile (MB 4) (see Figure 4, left, on prior page) was developed. This profile has a reduced gauge corner relief compared to the MB1 profile.
The reason for not grinding directly to MB1 profile was due to the reduced production capacity of the switch grinder in service at that time. To grind the MB1 profile from a deformed profile would have been very time consuming. Grinding in steps was the answer to the problem. In , some switches were ground to the target MB1profile for test purposes. These switches are monitored closely, and the MB1 profile is expected to become the standard for turnouts.
On Malmbanan, the upper part of the switch blade point is in many cases exposed to cracking due to a local overload when the wheels are moving from the stock rail to the switch blade. Due to wear, both natural and artificial by repeated grinding, the stock rail is lowered over time with respect to the tip of the switch blade. To minimize the risk of cracking of the critical upper part, the switch blade is lifted 6 mm before grinding (see Figure 6). Because of the metal removal by grinding from the top portion of the switch blade, the transition point from the blade to stock rail is moved toward the frog.
In Sweden, the annual grinding budget was earlier decided by each region or local hub. In many cases, the grinding budget was reduced due to economic measures or postponed until the following year. In , a central funding source was established, with each region reporting its grinding needs to the head office in order to &#;jointly&#; determine maintenance priorities. Rail grinding has since become a higher priority maintenance procedure on Malmbanan and other lines at Banverket.
Today, planning of the grinding operation is managed in a &#;turnkey&#; fashion. Spark Trade AB, a Swedish company, is subcontracted by the grinding company to plan, execute and ensure quality control of the daily work, including the organization of pilots, road guards and responsibility for all necessary service arrangements.
At present, grinding on the Malmbanan ore line is performed once a year. All curves are ground and switches are ground each year at 30-MGT intervals. Tangent track is ground every third year, at 90-MGT intervals. The development of grinding profiles on Malmbanan has been performed in close cooperation between Banverket, the transportation company MTAB (responsible for the vehicles) and the grinding contractor. This cooperation has been characterized by open discussion between the three parties, aimed at improving the contact between wheel and rail.
Future Work
Future grinding work of the ore line will focus on increasing the 30-tonne axle loads and 30-MGT annual tonnage. The MB1 and MB3 profiles will be used on open track and the MB1 and MB4 profiles will be used in turnouts. A new research project will be launched on Malmbanan this year to identify the presence and number of RCF defects through the use of manually operated Eddy-Current equipment. Depending on the results, the grinding strategy &#; grinding cycles, metal-removal rates, optimized profile designs &#; may be modified. A complete track renewal between Kiruna and the Norwegian border will be completed by . All of the existing 50E3 rail will be replaced by 60E1 rail. The new rail will be immediately profiled to the appropriate profiles MB1 or MB3 profiles.
Banverket also continues to investigate lubrication techniques and the development of improved grades of rail steels, such as bainitic steels and steel grades with higher carbon content, which should provide improved fatigue properties and wear resistance. These and ongoing improvements to rail grinding practices continue to contribute to improving overall life cycle costs on the Malmbanan and other railway lines.
Anders Frick is Senior Metallurgist, Banverket, Swedish Rail Administration, Track Engineering. Dr. Wolfgang Schoech is Manager of External Affairs, Speno International SA
References
(1) Nilsson P., Wheel/Rail Interaction &#; From theory to practice, 6th International Conference on contact Mechanics and Wear or Rail/Wheel Systems &#; CM, Gothenburg
rail trak lbs. question - RAILforum
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Posted by boyishcolt (Member # ) on
05:49 PM
:do most railroad company's use 115 lbs trak now? what was the highest lbs. trak used?
Posted by CG96 (Member # ) on
06:10 PM
:No. Many regional railroads and shortlines use rail of 90-lbs/yd and 112-lbs/yd on their yard lines and mains. Most class 1 RR's use 136 lbs/yd rail on their main lines, and lighter weight rail (obviously) on the secondary lines. The heaviest weight of rail currently in use in North America is 136 lbs/yd rail.
Posted by boyishcolt (Member # ) on
07:02 PM
:thanks cg96
did they ever use a higher weight?
i was surprised to lean that illinois after spendind millions on high speed rail up grades between CHI and springfield was only
115 lbs rail
Posted by Sheriff (Member # ) on
10:05 PM
:boyishcolt:
I think that the 136# rail is the largest they use. I have never heard of any heavier rail. It is treated a little better now than it was years ago though. I think they test and treat it to withstand about 117 degrees F before it starts to kink. CG96 is right on the money about the main lines. Most all the class A railroads use the 136# rail for their main line.
Posted by George Harris (Member # ) on
11:38 PM
:OK, here are the facts: The following is the sum of the different rail sections installed from to . For most of the earlier years, the quantities are for the US Class I railroads only, for most years the US and Canada, for some the US, Canada, and Mexico, and a few years are thought to include transit systems, while most do not. Where both are quoted, there were at times significant differences between rails purchased and rails installed. Imported rails are not included in earlier years, but in those years imports were minimal. Therefore, what you have here gives a general idea, but is not necessarily exact.
The heaviest rail ever produced in the US, and most likely in the world is the 155PS. "PS" means Pennsylvania Standard. This section was designed by and used by the Pennsylvania Railroad. It was designed in , but production had ceased before . It is unlikely that there is any left in main track. The next heaviest was the 140PS also designed in , which was later adopted by the American Railway Engineering Association (AREA) as a "recommended section" and its designation changed to 140RE. It was the primary section used by PRR, then PC, then in the early years of Conrail. Production went to under 50 track-miles per year after and ceased in . About two years ago the AREMA proposed a new section, the 141AB which is essentially a modification of the 136RE with an imporved shape and slightly larger head. I have no information on who is using this or the quantities since it came in to being after the end of my collection of statistics. From the late 's in the east and mid 's in the west the primary mainline sections used were 136RE (originally 136CF&I) in the west, 132RE in the east with the exception of 133RE on the Union Pacific, 122CB on the C&O/B&O 127DY then 136NYC on the New York Central and 140RE on PRR/PC. Where they bought new rail for them at all, on medium traffic lines most roads used 115RE but some western roads used 119RE (originally 119CF&I). Most rails lighter than 100 pounds per yard have been produced in negligible quantities for a number of years.
Quantities are in track-miles. Sections for which the 35 year total was less then 200 track miles are not listed. Numbers are rounded to the lesser of 100 miles or two significant figures.
Section----Total 62-96----per year 94-96
140 RE--------4,700--------------0-
136 RE-------35,900-----------1,990
136 NYC---------510--------------0-
133 RE-------10,900-------------380
132 RE-------37,300-------------140
130 RE-HF-------210--------------0-
122 CB--------3,400--------------0-
119 RE--------5,700---------------7
115 RE-------29,200-------------475
100 RE--------2,300--------------21
100 RE-HF-------840--------------0-
100 ARA-A-----6,200--------------23
100 ARA-B-------390*-------------35
100 ASCE--------220--------------0-
90 ARA-A-----1,500--------------0-
85 ASCE--------540--------------0-
85 CP----------520--------------0-
80 ASCE--------280--------------0-
(some sections are not listed, therefore sum is greater that the list of items)
Total all---142,000-----------3,100
*This quantity is significantly under-reported since this is the proimary sections used by NYCTA and some other northeast transit systems, and on the only time I was there, I saw a pile of 100ARA-B rail fresh out of the mill at Steelton in that amounted to about 100 tons.
The average weight of all rails for was 131.8 pounds per yard.
As to the statements on rail temperature: There seems to be a little misunderstanding here. Theere are a number of issues involved in rail life. Shape, support, hardness, brittleness, grinding program, control of wheel flats, etc. Where temperature comes in is the issue of setting the zero-stress temperature. In other words, laying the rail so that a particular temperature the rail is in neither tension nor compression due to thermal effects.
If this temperature is set too low, the rail may buckle due to high compressive foreces when the rail gets hot. If it is set too high, there may be pull-aparts at welds when the rail is cold. A pull apart can be less dangerous and is more easily detected in signalled track, as it breaks the track circuit. A buckle is usually only found in operation, and can result in derailment. Since a long steel rail is almost like a rubber band, keeping the rail in tension most of the time is desirable. That has become the normal American practice. It requires good steel, good quality rails, and storng insulated joints to work. The temperature to consider is rail temperature, not air temperature. While rail temperature will not go below air temperature, it can go above it, particularly in desert climates. Extensive calculations of stresses in rails and buckling forces have been done to detemine the reasonable range of zero stress temperature. Much of this is to counter that ingrained part of engineering education which says you must allow for thermal expansion and contraction of steel. Actually, in rail your basis is that the rail will not move and temperature effects are turned into internal forces. It has been the general conclusion in the US (and Canada and Mexico) that the zero stress temperature should be toward the high end of the temperature range and a formula of (2H+L)/3 + C is normally used, where "H" is the normal high rail temerature and "L" is the normal low rail temperatue, and "C" is some added constant, which is usually the Chief Engineer's opinion, and is normally in the range of 15 to 25 degrees F.
The Europeans, which generally use lower strength rail steel and smaller rail sections, tend to keep their zero stress temperatures lower and then go to great lengths to provide huge ballast shoulders to prevent buckling. By so doing, they appear to be wasting a lot of money for no appreciable benefit.
[This message has been edited by George Harris (edited 02-01-).]
12:40 AM
:thanks george
Posted by Geoff Mayo (Member # 153) on
01:32 AM
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:RE Europeans use lower strength rail - do you mean the lbs/yard or whatever? If so, I'm not sure you're correct in that department as I'm pretty sure much of the UK network is 135lbs or the metric equivalent...
Geoff M.
01:44 AM
:Very informative. I had no idea that there were so many weights of rail used. I thought there were just a few, for example 112-lbs, 115-lbs, 126-lbs, 132-lbs, and 136-lbs. i didn't know about the 140 - 155 lbs/yd rail. That must have been quite something. Thank you, George.
Posted by George Harris (Member # ) on
04:17 AM
:To geoffm: I meant all of the above, and yes I am sure. I have copies of the rail specifications and track standards used by several of the European systems, and a copy of a German booklet listing many of the sections used in Europe and some of the other countries around the world.
Until recently the British standard was 113 lb/yd and was called 113A. I understand that they have recently adopted the UIC60 section, which makes no sense at all to me because it has a 150 mm wide base compared to the BS113A's 5.5 inch = 139.7 mm wide base. One thing for certain, if you have a system that is for the most part in concrete ties, the last thing you want to do is change the base width of your rail section, because the seats for the rails and attaching points for the rail clips are built into the tie. BS113A is a thick web version of their former main line section, which was BS110, which is essentially identical with UIC54. This rail is very similar to the 112RE.
A lot of the published information is done in such a way as to make comparison difficult. For example, in North America we usually quote freight cars by their carrying capacity, while the Europeans quote them by gross weight. That is, when we talk about a 100 ton car, we mean a freight car with a capacity of 100 tons, which usually means a gross weight of 263,000 pounds = 119.3 tonnes (metric tons of kg each), while when a European railroader refers to a 100 tonne wagon, he means a car of that gross weight, which would be 220,000 pounds, which was usually the allowable gross weight of what we would refer to as a "70 ton" car. Further, only Britian and a few specialized lines allow loads that heavy. For most of continental Europe outside the former Soviet Union five foot gauge lines, the axle load limit is 22.5 tonnes = 49,600lbs or 198,400 lbs for a four axle car, and most axle loads, including engines are less than that.
Rail: American Rail is specified primarily by metallurical limits and hardness. European, and most others, rail is specificed primarily by metallurgical limits and tensile striegth.
The Metals Handbook by the American Society for Metals provides information on the relationship between hardness and tensile strength for rolled steel sections.
Without going too deep, here are some of the comparisons:
Factor----------AREMA----BS11-WRA--UIC/EN-900A
Carbon, min------0.74%----0.65%-----0.60%
Carbon, max------0.84%----0.80%-----0.80%
Harness, brinell hardness number
BHN, min----------300------263*------263*
Tensile strength in Newton/mm^2, then converted to pounds per sq inch.
Tensile N--------#-----880-------880
Tensile ksi-------145#-----128-------128
Elongation @ break:-9%------8%-------10%
*from Metals Handbook for defined tensile strength
#from Metals Handbook for defined hardness
NOte also that the European definition is for ultimate tensile strength, which is significantly higher than the yield strength more commonly used in the US to define steel strength. If loads stay below yield strength, the material life under repeated load is essentially infinite.
This should make it obvious that rail to the American specification is stronger. It has to be. Our allowed axle loads are much highe than those in Europe. The European and British rails in these comparisons is their middle grade, not their lowest grade.
Shape: This is too complex to go into in any detail, but there are two parts, wheel rail contact pattern and internal stress distribution. A couple of points: The European sections all have relatively small head to web radii, and this is particularly true for the UIC60 section (120 lb/yd) which is the current premier section that they market arould the world as the world class international rail section. Increase in this radius was the main factor in the redesign of the 112RE and 131RE into the 115RE and 132RE sections, respectively. While I do not know of any instances where this small head-web radius has proven to be a problem with the UIC60, there are virtually no installations, if not simply no installation of this rail where the axle loads are heavy enough for it to likely be a problem. Wheel rail contact appeas also to be better with the American 10 inch=254 mm crown radius instead of teh 300 mm crown radius of the UIC sections. In fact, the current analysis suggest that even a 10 inch crown radius is probably too large.
The Russians use a rail sections that is approximately equivalent to the 132RE that they call the P65. Remeber that in the Russian alphabet, Russia starts with a P. I do not know anything about its metallurgy and strength, either theoretically or in practice, nor about the allowed and normal loads carried by the Russian system.
The 136RE or a slightly modified metric derivitive thereof is use in heavy haul lines in Australia and, I think, Brazil.
The main reason that European tracks tend to look better and ride better can be summed up in one word: Money. The European systems spend money on track maintenance and upgrades that is in the level of died and gone to heaven for an American track engineer. But these systems do not pay taxes or make a profit, instead they consume huge amounts of government money. Given the materials and techniques developed over the years to get the best bang for your buck and a track budget per passing ton of somewhere over half that spent in Europe, we could have the best track in the world in a few years.
Concerning the upgrade is Illinois: I have been told that much of that line used to be in 112RE. The relay with 115RE was to avoid having to replace the tie plates since both 112 and 115 are 5 1/2 inch base rails. I had heard that the curves or some of them at least were being relaid with heavier rail, whether 136RE or something else, I do not know. It might be 133RE if Union Pacific made the choice. If SP, most likely 136.
04:17 AM
:Slight corection - most of the UK is either 115lb or 60kg - the latter being the current standard for new and replaced rails.
Geoff M.
04:26 AM
:Above comment posted before seeing George's latest post. While I'm sure you know your metals and your rails, I'm also pretty sure European engineers know how to design rails, which you seem to infer they don't!
After all, you can't run 186mph trains on shoddy track. Okay, so a Eurostar isn't as heavy as a double stack container or tanker, but axle weight is not the only factor in rail design.
Just out of interest, any idea why US rails are spiked whereas the UK (and possibly Europe) tend to use Pandrol clips?
Geoff M.
06:14 AM
:George
thanks for the information
so from your enginers point of view
with out cost being a factor
what is the best and most durable design for trak in the US?
Posted by rresor (Member # 128) on
10:26 AM
:Let me just add one note to George Harris' informative posts:
141AB rail is now standard for main line installations on UP and BNSF, and others are beginning to use it as well. I saw my first 141 on a former Conrail line near Albany, NY in the fall of . It, like 136RE, is essentially a "fattening up" of the 132RE section. Base and "fishing" (web) are the same as 132, with more metal in the head.
A note on elastic fasteners: they are necessary on concrete ties, which are much more common in Europe than North America.
And as to rail design, I believe George Harris was trying to make the point that a larger head radius was needed where contact stresses were very high. A 22 ton axle load is the maximum permitted in most of Europe, while in North America a 36 ton axle load is common.
04:28 PM
:rresor:
why did UP use 115 (some used) on the Springfield to CHI rebuild?? if hey are useing 141AB as a standard?
Posted by George Harris (Member # ) on
04:14 AM
:to rresor: Thanks for the information on the 141. I have been working outside the US for over 5 years and tend to get a little behind on what is going on there.
The following may be getting a little too technical for this venue.
A comment: Since rail design is more experimental than theoretical, generally rail shapes are changed as a result of problems with existing shapes.
Another comment, primarily to goeffm, yes I do think that American rail in both shape and other factors is better, in fact head and shoulders above, that of Europe. And that is mainly because American rail is worked a lot harder so more problems present themselves on the one hand, and because everyone who works with it has their own ideas and with multiple private companies have had more chances to try them out, and therefore there has been much more experimentation with various shapes in the US and Canada. For other factors in track, more later.
To rresor: Rail head radius: It appears that you may have misunderstand the point I was trying to make.
First: radius at the bottom of the head. The European problem as far as load capacity is the radius at the bottom of the head where it meets the web of the rail. This is the primary factor behind the 112lb section being redesigned into the 115 and the 131 into the 132. If this radius is too small it results in high internal stresses at the intersection of the head and web. This was discovered due to rail failures in this area in worn rail in the later part of World War II. This radius was increased from 1/2 inch to 3/4 inch, Problem solved, even though average and maximum axle loads have gone up significantly since. In the UIC60, the radius at this location is 7 mm. The head depth is greater, the bottom slope greater, and rails are pulled out of track with much less wear than in the US, so they have as yet had no problem. However, it will bear watching in the high speed lines as the rails wear, as wheel rail impact is a V^2 function, so a 300 km/h light axle passenger train may be as hard on rail as a 50 mph coal train. As yet the European high speed lines have not had a high amount of passing tonnage on their rails. The Japanese, which have had a large volume of tonnage on their high speed lines use a rail that has a large head to web radius.
Now: radius at the top of the head. Here we have the wheel contact point. The other major change in the section redesign was to change the crown radius from 14 inches to 10 inches. Not everyone was convinced, as the CF&I designs, 136, 119, and 106, kept the 14 inch crown, but with a larger gauge corner radius. I think these sections were developed sometime in the mid 's but do not know exactly. Can somebody tell me when these sections were first introduced and first used? First a comment, there are actually usually three radii on the rail head: A central large radius, with a width of about 1.25 to 1.4 inches, second a shoulder radius on each side of 1.25 inches, and finally a corner radius from this second radius to the side which is 9/16 inch on the 136 and 119 and 3/8 inch on 115, 132, 133, 140. As noted, since rail shape design is more experimentally modified than theoretically modified, serious re-analysis of head shapes began with the advent of grinding programs to try to extend the life of rail as more and more traffic became to be concentrated on less and less track. As a result, the 136 pound rail was produced for a while with four different crown shapes. There was the original with the 14 inch crown radius; a 10 inch crown radius version, which was later became the standard without any change in section name; an 8 inch crown version developed in Canada, first used by British Columbia and then adopted by Canadian Pacific; and a 4 inch crown version ordered by CN for use on curves only. The new 141AB has an 8 inch crown radius, so even though it seems intuitively illogical, it appears that a smaller crown radius actually performs better under heavy axle loads. This may be true virtually regardless of axle load, as use of a 200 mm (almost exactly 8 inches) crown was found to be the optimum in at least one high volume but low axle load passenger line.
As the man said, I am not sure that I understand all that I know about this subject.
To goeffm: High Speed Track: While a good wheel rail contact path is necessary for high speed, it is also very important and ordinary railroad speeds. What is necessary at high speeds is a good quality alignment both macro and micro. by macro, I mean very larger radius curves, use of variable rate spirals, large vertical curves. By micro I mean careful attention to deviations from line, level, and cross level in the track. A very wide range of track forms can be and are used. You will usually find that each developer swears that their own is best and all others are inferior. Such items as specific components and even track gauge are not really that important as to the possibility of running high speed. Proper component selection can have a lot to do with the maintainability of the system. A lot of the same considerations apply wheter you are running 50 mph or 200 mph. There are some dynamic factors that come into play at higher speeds, but it does not appear that even when the French got to 515 km/h (320 mph) that these were coming into play. They did not go faster simply because thay did not have enough track length to speed up and slow down. By the same token, when riding the Japanese Shinkansen at 285 km/h (177 mph), there is no sense that they are in any way pushing the envelope of normal wheels on rails operation.
I am not down on all things European, it is just that having studied and used some of their materials, I will say that a lot of it looks better at a distance than it does up close. Again, it is money. Economics appears to be much less of a factor in their decision making processes. They spend a lot more on providing a good passenger service and on maintenance of their railways in general. The German turnout geometic concepts and design theories for high speed turnouts are very good but some of their applications of those designs leave you scratching your head. You could take their theories and better their current designs. A lot of their components are somewhat high-maintenance, and a lot of the details of rounding and chamfering that we use they do not. Generaly, I find European turnout designs better geometrically, but more complex in componentry and worse in durability, even theough they do have some very good components. What we want is to pick the items, not buy the store.
Elastic fastenings: That is one excellent deveopment from Europe. Pandrol had the right idea, easy to install and remove, and no bolts to keep tight. Some of these come in two versions: a North American version and an everywhere else version that is not as strong. In Europe they use elastic fastenings even on wood ties because they have a philosophy that spikes into wood are not safe except on slow industrial trackage. When they use elastic fastenings on wood, it is usually with a cast baseplate that is held to the tie with four large lagscrews with the clips each attached to the plate by another bolt, unless the clip is Pandrol. Needless to say it is expensive in both material and labor.
to boyishcolt: Best track: This is like asking the doctor for free medical advice. For starts, good drainage and good subgrade material. In fact the first three rules of good road or railroad design are drainage, drainage, drainage. One man years ago described a lot of what we do in track upgrading and maintenance as trying to build a two story brick house on a tarpaper shack foundation. If you do not have good material under the track nothing you do will stay good. Do your best superhighway type earthwork and have a good ditch on each side, then put on about 8 inches of good subballast about 24 to 28 feet wide and with a good crown plus about a 4 inch layer of a good asphalt base course about 12 feet wide directly under where the ballast will be. On this have at least 12 inches of ballast under the bottom of the ties. If the track is relatively straight, traffic density and speeds are normal range, then the wood tie and spike is as good as any unless the climate is Florida or south Lousisana. Use two rail holding and two plate holding spikes. Have ballast shoulders of 12 to 15 inches level with the top of the ties. Use large tie plates, 141AB rail if you will have heavy freight. Now if we are talking crooked, go to concrete ties with Pandrol Fastclips. Concrete is also a good idea if you want to run 100 mph plus or are building in high rot areas. In general, you should not be using concrete ties if wood ties will perform well. I know this is not the current revealed wisdom, but concrete is much less forgiving of poor support, high impacts from flats or out of round wheels and othes such surprises than concrete. Of course 100% welded rail, glued insulated joints.
[This message has been edited by George Harris (edited 02-03-).]
04:28 AM
:why Asphalt and not psi PCC base?
Posted by George Harris (Member # ) on
06:24 PM
:Flexibility. Asphalt bends. Concrete cracks and mud pumps through the cracks. Asphalt road surfaces degrade due to evaporation of volitile components from sunlight and direct wheel contact. Under ballast this does not happen. The mix should be richer in binder than normally used in a road base course. Unversity of Kentucky did some studies funded by Asphalt Institute a number of years ago. I saw a test section in Oklahoma City in about which had been in place for 10 years. You could see exactly where it ended without digging it up. Filter fabric had clogged. Are you an engineer?
[This message has been edited by George Harris (edited 02-03-).]
11:29 PM
:flexcrete with fiber usally around psi is a good base and with extream freeze thaw
cycle in Illinois (70F to 32F) in 24 hours and blackdirt. i beleive Germany also uses this mix 3" PSI 8"PSI on roadway
but in the south there are not these extreems
but i read Germany used Flexcrete on an test basis. but is more expensive than asphalt.so it was not used again.which is usally the case with Asphalt vers. Concrete and the asphalt industry has much better lobbying skills.than the concrete industry. i will look up and read that research from Kt.
Posted by George Harris (Member # ) on
01:58 AM
:If we were talking road surface, I believe concrete to be far better, and would say would have a lower lifecycle cost. No hot weather rutting, etc. Far a track base it is a waste of money. Freeae thaw is not a problem for the asphalt track base either. Oklahoma has plenty of that, too.
Posted by Geoff Mayo (Member # 153) on
11:43 AM
:I agree with pretty much everything you say except two points:
1. In your opnion US rail is better than European rail - but you also say that US rail takes more of a pounding. So what I believe you really mean is that US rail is *more suited to US conditions* whereas European rail is *more suited to European conditions*. Why use over-engineered rails for lightly used branch lines that see half a dozen light carriages a day?
2. "Such items as specific components and even track gauge are not really that important as to the possibility of running high speed." - I think you'll find guage is extremely important. Experiments with the TGV trials proved this. With a slightly wider gauge, severe hunting was experienced which resulted in deformed track. I *think* high speed lines are more mm instead of mm. Hazy memory there and I'm no expert.
Geoff M.
07:18 PM
:to goeffm:
your point 1: I am talking about shape, hardness, metallurgy in rail in main line srevice in both cases. For branch lines, you use whatever is left over on both sides of the Atlantic.
your point 2. I was not talking about the relation between track gauge and wheel gauge, which can be very important in wear and ride quality issues, but gauge as an absolute value to say that there is nothing "magic" about standard gauge per se. If you want to run high speed service you can whether your gauge is , , , , , or some other number. (4ft 8.5in, 5ft, 5ft 3in, 3ft 6in, 3ft 3 3/8in, naming some of the more common track gauges used around the world)
By using mm for the Shinkansen instead of the mm gauge used by the rest of their railways, the Japanese gave themselve a multi-gauge problem they did not have, but they did act with the best knowledge available at the time, which treated high speeds on maller gauges as axiomatically impossible. They also gained advantage from the wider gauge by using wider coaches with five across seating. What this does mean is no through running, so there is a lot of changing of trains which is both a passenger inconvenience and an operation inefficiency. This problem the French avoided. However, their equipment on the TGV is no larger in cross section than that used on the Japanese mm gauge lines.
04:21 AM
:I believe Shinkansen track is used only by Shinkansen trains on purpose.
And the ride is silky smooth!
Posted by panamaclipper (Member # ) on
09:43 AM
:I know the freight wagons (they don't call them cars) I've seen on the British rail lines are just a fraction of the size of ours. Of course, the passenger coaches they use are full size.
Posted by Geoff Mayo (Member # 153) on
10:01 AM
:We do call them cars sometimes, it's a regional thing.
The UK loading gauge is smaller than the US ones, smaller than even Eastern US, hence smaller trains. Newer lines are built to a larger loading gauge. I can't remember the standard but basically so European freight traffic will fit along key routes.
Geoff M.
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