track dimensions

[Anonymous]

I am student studying mechanical engineering at Leeds university, England, I’m doing a project on the stresses in rail tracks and what causes them to fracture. Im sure there must be standard dimensions and materials used for the rails, pins etc but i’m unable to find them anywhere. If anyone could suggest a source where I could find this information it would be greatly appreciated. Thank you

[jchnhtfd]

AREA Manuals. Only, they are only available on the web by membership -- which isn't inexpensive. But almost any good (older!) Manual on Civil Engineering should have them.

You should be aware, though, that there really aren't standard dimensions for rails, in particular. They are specified by weight in pounds per yard, but the dimensional drawings for them vary somewhat from mill to mill. Some railroads -- notably the Pennsylvania Railroad -- had standard cross sections.

I'll spend a little time and try and track some more material and references on this down for you. I used to have a complete set of AREA manuals -- but they belonged to the company I worked for (CN) and they (CN) would have taken an exceedingly dim view of my taking them when I left!

[kenneo]

FRA Track Standards would be helpful also. http://www.fra.dot.gov/site/index.htm

[dehusman]

Fractures in rail are most commonly caused by defects in the steel or temperature changes causing contraction of the rail and exceeding its tensile strength.

Dave H.

[Anonymous]

AREA bullitins are good for dimentions.[:D] Another book to look at is the Rail Defect Manual by Sperry rail service. Its a small guide, but is has photos and diagrams showing differant types of fissures and fractures that commonly happen in rails. It also gives a history of rail, and how rail is created. Sperry's website is www.sperryrail.com, and is located in Danbury Conneticut, USA.

Hope that helps

[Anonymous]

MUDCHICKEN............Where are you, your expertice is needed!

[jchnhtfd]

If you can find a copy in your library or interlibrary loan: Standard Handbook for Civil Engineers, Frederick S. Merritt, Editor, McGraw-Hill Book Company, New York, USA, 1968. Section 19 is all about US and Canadian railway engineering practice, and you might find it helpful -- to put it mildly. It has, among other things, a pretty good table of properties of rail sections and a discussion of steels used.

As was noted above, fractures in rails are most often fatigue failures; out and out abrupt fractures are rare (although, as Dave H. noted, they do occasionaly happen in welded rail in extremely cold temperatures: a combination of being below the particular steel's transition to brittle properties and excess tension in the rail and, usually, an impact load such as a slid flat wheel). The nastiest form of failure mode involves shelly rail (refer to trainheartedguy's Sperry Rail Manual for a good description) and a propagation of a fatigue failure from a shelled area. The reason it's nasty is that it is very hard to find a fatigue fracture in a shelly area.

In your analysis, you should keep in mind that the rail is only one part of the track structure, and that any analysis of the stresses in rail must -- absolutely must -- take into account the complete structure, including tie plates, ties, ballast and subballast, and the behaviour of the whole assemblage under load for a distance of several full car lengths (at least) from the point of load application. There is tremendous flexibility in the track structure, on purpose. I think you will find that a 40 ton axle loading (not at all uncommon these days on this side of the pond) will do horrible things to a rigidly supported rail -- even the heaviest sections. The system wouldn't work without the flexibility built into it (as we found in the early days of concrete ties, by the way).

There are a number of causes for shelly rail -- some are discussed in the Sperry book -- and you will probably get as many theories as you talk to engineers. An interesting area of study, however, particularly if you are into finite element analysis, is the dynamic interaction between the wheel and the rail head. Compare a perfectly round wheel (there aren't many!) with one with flat spots, for instance, or consider the imbalance in a steam engine and its effect. The stress reversals perpendicular to the plane of the rail head are astonishing...

Good luck!

Mudchicken -- further thoughts?

[mudchicken]

Harbs:

(1) AREA no longer exists. Since 1998 it became AREMA (www.AREMA.org, AMERICAN RAILWAY ENGINEERING & MAINTENANCE ASSOCIATION).....You can buy individual Chapters of their manuals...You apparently want Chapter4 (Rail)

(2) You also ought to talk to Randy Bowman, AREMA C-4's committee chair (The folks that write & edit the Manual, he is Norfolk Southern's chief metallurgical engineer, contact him at [e-mail])

(3) Talk to the AAR's transportation test track people AAR/TTC at Pueblo(*** Rief, Al Reinschmidt, & Company) @ www.AAR.org and the TTC itself at http://www.AAR.com

If you have not been aware, AAR has had a group of six "blue ribbon" specialists wandering around England (your back yard) since the restrictions from the mad cow pandemic were removed......looking into your rash of broken rail issues that plague your country's track infrastructure....

Have fun with curve angle of attack, profiles, track modulus, L/V ratios and all that good "mind candy"!

jch and ironken- just got back from KCS/Texas Mexican between Laredo and Corpus Christi with a severe case of "roadbutt" and windshield time. Thanx for looking out for the old bird!

Mudchicken