rails

[BigInch]

There is no railroad forum.

While discussing some pipe stress problems today, I wondered what the railroads are doing these days in regards to thermal expansion on high speed lines. I thought I saw that high speed rails are welded together nowdays, ditching the old fishplate bolt-up method that left gaps between rails, which incidently served to take up thermal growth. So questions are,

Are high speed rails welded together.
If so, how is thermal expansion considered.
Are the rails being anchored sufficiently to the tie downs to resist thermal expansion and compression buckling, or is some other method being used?

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[btrueblood]

According to the following authoritative sources, the tracks are laid down with degree of pre-stretch, or tension, to reduce the motion induced by thermal expansion.

http://www.google.com/#sclient=psy-...on.2,or.r_gc.r_pw.,cf.osb&fp=b77b44dc3758e796

http://en.wikipedia.org/wiki/Track_(rail_transport)#Continuous_welded_rail

 

[CorBlimeyLimey]

Some reasonable answers given at

http://boards.straightdope.com/sdmb/showthread.php?t=264991

 

[arunmrao]

Mint,will have something useful to contribute.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[BigInch]

Thanks. Sorry. I'm getting used to Eng-Tips instant gratification answers. I could have wikied that myself, if I wasn't so lazy tonight. So, some resistance is provided by the attachment, which can be combined with pretensioning. I don't think I want to pretension a 52" pipe though and thermite is only for attaching CP test leads. Interesting.




Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[btrueblood]

Trying to envision thermite welded 52" gas pipeline...were you gonna hot-tap that?

 

[btrueblood]

Oh, and no problem being yer Wiki linker, Big. Gotta go do some research today on the European PED. My sister company makes subsea valves and components, and apparently (according to their customer's engineer) the PED has been updated since '97 and our cert statement is out of date. Since I was the schmuck who did the original research to write the cert statement, I get to go through the whole research string all over again...any suggestions would be helpful.

 

[JStephen]

As far as I know, most rail in the US is continuous welded rail now- it's not limited to high-speed applications.

 

[stanier]

BigInch,

They have been pre tensioning welded rail in the UK & Australia for fifty years.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[JJPellin]

My father worked for a railroad in the US for about 35 years. He would love to tell stories about railroad work. As already noted, most rail in the US is welded. It is fabricated in 1/4 mile sections, laid and welded. To hold the additional loads, they use more ties and more ballast than the old system. But, in extremely long straight runs, they still have problems.

In west Texas, they will occasionally get a "sun kink". The rail tears loose from the ties and jumps off to the outside of a curve on a hot summer day. In order to get the rail back into position, they might have to cut out a couple of feet. They schedule to come back in the winter and make appropriate cuts and add rail back in so that the tension does not become too great.

In very cold areas, they can have the opposite problem. If the rail breaks in the middle of winter in Nebraska, a gap of a foot or more could open up. Rather than adding rail and then having to come back and remove it later, they have an alternative. The old timers would say it’s time to “soak a rope.” As the story goes, they coil up 100 yards of 1” hemp rope in a 55 gallon drum and fill it with diesel fuel. They lay it out of the foot of the rail on the upwind side and light it on fire. The burning rope heats the rail up sufficiently to grow the break back together. They weld it quickly while the rope is still burning.

I should note that I have no experience with rail. These are old stories told by old railroaders to other old railroaders. And, from my experience, old railroaders are a bit like old fishermen. They like to tell stories and some of them are actually true.


Johnny Pellin

 

[arunmrao]

Last week with the onset of winter ,a section of welded rail,cracked with a loud noise in Eastern part of India. A major accident was averted as the sound ,alerted a local man living near.



_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[patprimmer]

I think it is fairly common practice to use the rails to transmit electric signals so the signal controllers can see the position of trains on the track. Surely a break in a rail would show up on such a system.



Regards
Pat
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[arunmrao]

Copper and aluminum attract pilferage. They are stolen,even before they are laid!!

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[patprimmer]

arunmrao

I won't say it never happens, but that is not really such a problem here.

Even though they use the tracks as conductors, they also have wires in parallel with regular attachments. I really don't know how it works other than to say the rails need to be insulated by plastic pads, of which I do know something about.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[BigInch]

Btrue,
Sorry, I'd like to help with that, but I don't work with PED. Mideast work is API/ASME based and/or pretty much entirely tied to company specs only.

The only thing I know, is what you do, that it has been updated since '97. BTW is that 1897, or 1997?

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[BigInch]

Stanier, I think it has been 45 years since I put a penny on the track and had an opportunity to look at a rail close up enough to tell what they were doing. The Milwaukee Road, Santa Fe and the Missouri, Kansas, Texas (MKT) still used fishplates in the 50's and 60's.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[btrueblood]

Big,

Thanks anyway. Not too much of an update. Finished going over the easy part last night...and think I know where the problem lies...but have not heard from the sister company yet to know what their customer is objecting to, so am just guessing right now.

 

[BigInch]

I have a "guide to the PDE" somewhere around here, but I havn't found the need to read it yet. Lemino.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[stanier]

Biginch,

There is still rail with fishplates in the UK. It is the major routes that have been upgraded with concrete sleepers, flat bottom and welded rail.

Many railway lines were laid with bull head track since the days of steel rail. (1890s) The concept was that the rail could be inverted as it wore. The rail sat on chairs and was held in place with wooden wedges. It was found that the rails could not be inverted as the top surface had worn so much that it could not withstand the load. Hence flat bottom rail was introduced. With it came concrete sleepers. In the UK the wooden sleepers would rot. In Australia the termites had a good feed.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[JStephen]

I think we have a line here locally that is bolted rail from the 40's. But then again, it gets about one train a day, if that, and that's at maybe 10 mph.