posted
I have seen a few times on the news that warped rails are a common problem right now in Europe, because of the heat wave they are experiencing.
The heat in Europe is still quite low compared to the heat we have in Arizona and I rarely hear of warped rails here.
I realize that with modern technology, the tracks in areas with known high temperatures are desinged for it. But how about 100 years ago? Trains ran through Arizona where the winter temperature was in the 30's, sometimes even the 20's. Then in the summer, the temperature was routinely from 110 to 115, sometimes in the low 120's. I am sure that sometimes the rails warped, but I have not read that it was a common problem. What is the difference with the rails in Europe?
------------------ Elias Valley Railroad (N-scale) www.geocities.com/evrr
posted
I don't know about proceedures Europeans use but track on 1st class RR's in the US is laid with knowledge of local conditions, ie, what is the average temperature in the local. They try to simulate this as they lay rail. Sometimes they lay rail at night, or use dry ice to cool it, or even artificially heat it to achieve, as nearly as possible, the mean temperature in each location.
Additionally, there are rail anchors applied which attach to the rail and fit snugly up against both sides of the ties. This forces the expansion to make the rail fatter and taller rather than to become longer, which is the normal and easiest way to expand.
Today rail is welded. Pre 1950's 39 foot rails were connected with a device called a joint. These had a small gap between the rails which absorbed some of the expansion but also created a weak spot in the track that created substantial maintenance costs. You can still see this on branch lines and in yard tracks where operating speed is slow.
Hope this brief explanation helps.
Posts: 467 | From: Prescott, AZ USA | Registered: Mar 2002
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posted
I appreciate your response. I am not sure this really explains the problem. I still don't fully understand. Over 100 years ago, they were able to build track that could withstand a temperature difference of 100 degrees, then I wonder why today the European railroads cannot withstand the weather.
posted
There have always been "sun kinks" on railroads. They do not always become public knowledge, but a recent ( last year) event in Maryland caused a derailment of an Amtrak train. That one was explained by recent maintenance that had not been completed.
The ballast that is the part of the track structure beneath and surrounding the ties not only cushions the impact of a trains weight and speed but also served to hold the tie in place. When track maintenance is done the ballast is disturbed and must be properly reinstalled (RR's call this tamping) or the complete track structure is weakened, which is what happened in MD.
These events happen occasionally, yes even on the 1st class US RR's, but are seldom publicized. Some of the freight train derailments that we occasionally hear about are caused this way. Perhaps the Europeans had underdesigned for the weather anomalies they are experienceing, but more likely they are getting publicity because everything associated with this unusual heat in Europe is getting more media play. And we should never underestimate the willingness of the media to over-dramatize events. Sometimes the story is more to get attention for the writer or his employer than to give us the information without "garnish" or a bias.
Once more, I hope this is helpful.
Posts: 467 | From: Prescott, AZ USA | Registered: Mar 2002
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posted
My guess...Could any of it have to do with "modern" welded rail? In years past most rails were short lengths (39 ft as discussed above), so there were a lot more expansion gaps for this kind of thing.
[This message has been edited by MPALMER (edited 08-16-2003).]
Posts: 874 | From: South Bay (LA County), Calif, USA | Registered: Aug 2000
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posted
Modern rails are laid according to the average local conditions +/- a suitable factor. The rails are actually stretched when laid so that in theory they are in tension when cold and in compression when warm. Temps in Europe have been AIUI abnormally high, ie even beyond the overload factor. You can only design for so many conditions.
Geoff M.
Posts: 2426 | From: Apple Valley, CA | Registered: Sep 2000
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posted
Welded rail has been used in the US since the 1950's. As discussed above, it is achored so that it must expand fatter and taller rather than the least resistance horizontally.
Welded rail, in the US, is laid in 1/4 mile strings and then those are weled together in the field to make even longer continuous welded rail. This is the standard on all major railroads principal routes. That is where their primary revenue sources are serviced so they obviously cannot tolerate problems with sun "kinks". Yes, they happen occasionally, almost always as a result of maintenance errors.
Posts: 467 | From: Prescott, AZ USA | Registered: Mar 2002
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