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Physical Plant - Track, Structures and Signals >> Railroad Infrastructure >> Dipped squared joints / rails bent into shallow arches
(Message started by: OperaTourist on Feb 6th, 2014, 8:44pm)

Title: Dipped squared joints / rails bent into shallow arches
Post by OperaTourist on Feb 6th, 2014, 8:44pm
Do any of you railroad fans know what is going on with the strange railroad track, in the attached photos?  According to the BBC journalist Jeremy Paxman, the railroad is in Sudan.  I have never seen rails so badly warped, yet still serviceable for slow traffic.   Might this be caused by desert heat and lack of maintenance?  Or perhaps those rails are deliberately warped, to act like speed bumps for railroad locomotives?   It's not easy to see the details, but the rails seem to be bent upward in the vertical plane, into shallow arches, between widely spaced cross-ties.  

You can see the movement, at 31 minutes into a video, at YouTube.com.  Title of the video is "Empire - Playing the Game".  The URL is currently
http://www.youtube.com/watch?v=reUswCW1cd0

In the video, you can see the locomotive and cars in tow are all bouncing and swaying, going only about 10 miles per hour.   At 33:30 in the video, the train runs much faster, on rails that are smooth and straight.  

Title: Re: A strange "What is this?" Why are these rails bent into shallow arches?
Post by George_Harris on Feb 7th, 2014, 12:27am

on 02/06/14 at 20:44:52, OperaTourist wrote:
Do any of you railroad fans know what is going on with the strange railroad track, in the attached photos?  According to the BBC journalist Jeremy Paxman, the railroad is in Sudan.  I have never seen rails so badly warped, yet still serviceable for slow traffic.   Might this be caused by desert heat and lack of maintenance?  Or perhaps those rails are deliberately warped, to act like speed bumps for railroad locomotives?   It's not easy to see the details, but the rails seem to be bent upward in the vertical plane, into shallow arches, between widely spaced cross-ties.  

You can see the movement, at 31 minutes into a video, at YouTube.com.  Title of the video is "Empire - Playing the Game".  The URL is currently
http://www.youtube.com/watch?v=reUswCW1cd0

In the video, you can see the locomotive and cars in tow are all bouncing and swaying, going only about 10 miles per hour.   At 33:30 in the video, the train runs much faster, on rails that are smooth and straight.  

If you have not seen rails so badly warped but the track still being used, you have lived a sheltered life.  This is reality for many low speed branch lines, at least in the past.  Many of the lines that were so low in traffic that they could not be better maintained are now gone.  I would suspect that this track could meet FRA Class 1 which means good for 15 mph passenger / 10 mph freight.

Since the joint is a weak spot in the track they will ALWAYS get beat down under traffic.  The norm is that the track at the joint area will be tamped to pull out the dip.  This reality of the weakness of the joint has led to the near universal adoption of welded rail, as it cuts approximately in half the effort required to maintain the track to any given standard.  

These rails started out straight.  Under traffic each wheel impact pushes the rail down a little.  Not coming along and tamping up the ties at the joint leads to the track looking like this.  

Look at the video and you see that the major movement is vertical with very little side to side rocking.  That is because this track has been built British / European style, that is with the joints opposite rather than staggered as is the normal American practice for jointed rail track.  In my opinion this is worse because both wheels on the axle hit the joints at the same time rather than one at a time.  Think of the difference when driving between hitting a pothole with one tire and hitting a trench across the road.  Even with the depths and widths being the same, it is more than twice the bounce.  

Remember, by the way, the zoom is turned up real high in these pictures, so the track is not as bad as it looks.

Was interested to notice that the coupling system appeared to be with knuckle couplers rather than the hook and screw system still used in freight in most of Europe, India, and a number of other places.

Title: Re: A strange "What is this?" Why are these rails bent into shallow arches?
Post by OperaTourist on Feb 7th, 2014, 2:38pm
Thanks for your very quick reply, George!   I now understand, this strange track is partly an optical illusion, caused by a telephoto lens.  But mostly, it is the usual condition of low speed branch lines.  

Yes, indeed!   I have led a sheltered life, riding on museum-tourist railroads that have well maintained track.   Of course, museum track probably gets only light, intermittent use.  And rough track would put more wear on the rolling equipment.  There is probably an optimal way to allocate maintenance resources, in a museum and tourism based enterprise.   A museum railroad is quite different from a railroad that is a transportation business that needs to earn profit by moving people and freight, long distances.

And additionally, it would probably be less than safe to build museum track in authentically dilapidated condition.  Or would it?  Perhaps, only for just a short distance, to demonstrate to museum visitors how miserable branch line train travel could be, in the olden days.    "Now, folks... we slow down to 10 miles per hour... you are about to see... and feel... why... crawling along branch lines was an exasperating way to travel..."  Do you know of any museum railroads that have such an exhibit?  It's another case of "history versus Hollywood".  In movies, the actors in old-time trains are hardly jostled.  Hardly anyone understands how rough travel used to be.  

Title: Re: A strange "What is this?" Why are these rails bent into shallow arches?
Post by George_Harris on Feb 7th, 2014, 9:00pm
A little more to explain a few things:

The Sudan Railway is 3’-6” track gauge (1067 mm), which is sometimes called the Cape Gauge as it is the South African standard.  However, it is not just used there.  It is also standard in Japan, Taiwan, New Zealand, parts of Australia, and some other places as well.  

Here is a partial quote from the Code of Federal Regulations:  If you want the whole thing concerning track safety, the reference is Title 49 Transportation, Part 213 Track Safety Standards, with the reference usually written 49CFR213, with or without spaces.  When going into Part 213, you must go to Subpart G for all requirements for tracks having speed limits above 90P/80F.  The whole thing:
http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title49/49cfr213_main_02.tpl


In looking at these numbers understand that these are SAFETY standards.  That is, the trains will stay on the track.  It does not mean the ride will be comfortable.  It won’ be.  In fact it could best be described as exciting.  

In Subpart A:  General

213.9 Classes of track: operating speed limits

Track Class…Max. freight speed…Max. passenger speed
Excepted…………….10……………………………N/A
Class 1………………..10……………………………15
Class 2………………..25……………………………30
Class 3………………..40……………………………60
Class 4………………..60……………………………80
Class 5………………..80……………………………98

In Subpart C:  Track Geometry

213.55 Track Alignment

Track Class…Tangent Track……………..………Curved Track  
…………………..deviation from ………….….deviation from middle
………………..middle of 62 ft line………….of 31 ft line…...of 62 ft line
Class 1……………..5 inches………………….……N/A…..……..….N/A
Class 2……………..3 inches…………………1 1/4inches………..3 inches
Class 3……………1 3/4 inches………….…1 1/4 inches……..1 3/4 inches
Class 4……………1 1/2 inches……………1 1/4 inches……1 1/2 inches
Class 5………………1 inches………..……..1/2 inches……..5/8 inches

213.63 Track Surface (this is relative elevation of points along the track)

Track………profile elev. difference …….deviation from…….crosslevel difference
Class……....middle of 62 ft line………..…zero crosslevel……..within 62 ft line
Class 1…………….3 1/2 inches……………….3 inches……………….3 inches
Class 2…………...2 3/4 inches………………..2 inches……..……..2 1/4 inches
Class 3…………...2 1/4 inches………………1 3/4 inches………..…2 inches
Class 4………..……2 inches……………………1 1/4 inches……………1 3/4 inches
Class 5……………1 1/4 inches………..……..1 inches…….…………1 1/2 inches

Go to Subpart G for information on higher classes and speeds



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