MBTA discovered that CSX did not de stress the Boston - Worchester double track rail. MBTA has several contracts completed or in progress to complete this work by end of 2015. That will prevent any heat restrictions on the route.
Question maybe for Balt. Is this standard practice on the CSX system wide ?
http://www.mbta.com/about_the_mbta/t_projects/default.asp?id=6442454462.
blue streak 1MBTA discovered that CSX did not de stress the Boston - Worchester double track rail.
There are people much more qualified than I am to address this question, but (from the relevant contract language) "Rail de-stressing shall include but not limited to cutting welded rail at selected intervals, removing rail anchors and/or clips, heating rail to desired neutral temperature, providing means for the rail to expand, re-anchoring or clipping the rail at the desired temperature, and re-welding the rail."
My understanding is that this is normal periodic maintenance for track that has long welded rail in areas with severe climate swings (as Twain pointed out, New England qualifies there!) It is also more likely that a Government agency running passenger service is more likely to 'deploy' funds to do this all at one time than CSX would.
Sun kinks in Summer - Pull-a-parts in Winter.
Welded rail is a technology that has yet to be completely mastered.
Never too old to have a happy childhood!
Welded rail is largely trouble free, with sun kinks and pull-aparts very rare when laid properly and the ballast section maintained. I would disagree with Balt; I feel it is a technology that has been mastered. Mastered, that is, in knowledge but not always in implementation, and so failures do occur.
When sun kinks occur the cause is usually external. A minimal ballast shoulder, or poor ballast, fails to provide the lateral restraint known to be required. Poor maintenance practices by track forces can introduce localized stresses. Those same localized stresses can also be responsible for pull-aparts. Pull-aparts are most prevalent in the first bitter cold snap after the rail is laid, taking advantage of the least flaw in the welds or rails.
Sun kinks have become a concern on many branch lines with jointed rail, when the temperature soars. Once upon a time those joints were kept lubricated by the local track forces. Now the joints can get "frozen" and no longer provide the necessary expansion and contraction needed. Rail anchors are often a bit iffy on a branch line. Many branches only run at night during the hottest part of the summer for this reason.
As an aside, "sun kinks", "track buckles" and "thermal misalignments" are all essentially different words describing much the same thing. The second seems to be preferred in formal circles.
John
blue streak 1 MBTA discovered that CSX did not de stress the Boston - Worchester double track rail. MBTA has several contracts completed or in progress to complete this work by end of 2015. That will prevent any heat restrictions on the route. Question maybe for Balt. Is this standard practice on the CSX system wide ? http://www.mbta.com/about_the_mbta/t_projects/default.asp?id=6442454462.
The article said that MBTA couldn't find the records, not that CSX didn't do it. It would be very doubtful for them have skipped this maintenance practice.
In many other parts of the world expansion joints are used to mitigate the need for this practice.
Most common practice is to set the neutral temperature on the high side making a pull-apart more likely than a buckle. The reasoning being that the signal system will detect a pull-apart but not a buckle
cx500 Sun kinks have become a concern on many branch lines with jointed rail, when the temperature soars. Once upon a time those joints were kept lubricated by the local track forces. Now the joints can get "frozen" and no longer provide the necessary expansion and contraction needed. Rail anchors are often a bit iffy on a branch line. Many branches only run at night during the hottest part of the summer for this reason.
I'm curious about the need for CWR on a branch line. (On a secondary main, sure.)
dakotafred cx500 Sun kinks have become a concern on many branch lines with jointed rail, when the temperature soars. Once upon a time those joints were kept lubricated by the local track forces. Now the joints can get "frozen" and no longer provide the necessary expansion and contraction needed. Rail anchors are often a bit iffy on a branch line. Many branches only run at night during the hottest part of the summer for this reason. I'm curious about the need for CWR on a branch line. (On a secondary main, sure.)
Yep, I read right thru CX's "jointed." I forgive myself because, unless I'm wrong again, the original subject was CWR.
dakotafredYep, I read right thru CX's "jointed." I forgive myself because, unless I'm wrong again, the original subject was CWR.
Actually, now that you put it that way, the original subject was de-stressing; the point of cx's post being that under 'negligent' conditions non-destressed jointed rail can act just the way non-destressed CWR can. But forgive yourself anyway.
De-stressing what? Or does CSX have other than CWR on its Boston-Worchester line?
dakotafredDe-stressing what? Or does CSX have other than CWR on Boston-Worcester?
De-stressing rail that has accumulated thermal-expansion stress and is therefore likelier to 'kink' as traffic passes over it. As noted, jointed rail can have that problem just as easily as CWR. Admittedly, it is probably easier to loosen some of the joints (with the rail at or near the neutral temperature) and release the stress that way than to treat the rail as if it were one piece...
Yes, technically the contract concerns performing de-stressing on a line laid with CWR, and the terms of the contract use language and procedures that are optimized for CWR. But it is the act of the de-stressing that is important; were the track in question laid with jointed rail (or lengths of welded rail short of CWR) there would still be a concern to ensure that the track was de-stressed if it could not be verified that this had been done in a documented fashion. That de-stressing would be done with different methods, but it would still involve adjusting the track with the rail at or near the neutral temperature to minimize tendency to kink in hot weather and pull apart or gap excessively in winter.
Wizlish On the other hand, repeatedly misspelling 'Worcester' is unforgivable, especially after I already quietly corrected it for you once.
On the other hand, repeatedly misspelling 'Worcester' is unforgivable, especially after I already quietly corrected it for you once.
My understanding is that CWR has a 'rail neutral temperature' where the rail is under no thermal stress. This can vary depending on the rail, and apparently CSX did not have the optimal RNT, resulting in kinks. MC and PDN can probably tell us more.
dakotafredSmall-favors department. I took my spelling from the OP. Who ever heard of Worcester?
You just need a little help. It's pronounced a bit funny. Here:
NorthWestMy understanding is that CWR has a 'rail neutral temperature' where the rail is under no thermal stress.
You have that a little sideways. The rail will be under 'no thermal stress' at whatever temperature it has just been laid, aligned and anchored. Thereafter its 'neutral temperature' would be that same temperature.
The reason to specify a rail neutral temperature is to lay the rail in a way that minimizes the stress that causes buckling/kink at the hot end of the temperature spectrum, or pull-aparts/open joints on the cold end. Now, the risks differ and the ability of the rail and track structure to resist the forces differs between tension and compression, so the actual neutral temperature selected is likely not just an 'average' temperature; it is also easier when doing track adjustment to heat up a length of rail than to cool it down (I confess I'm still amazed at the burning-rope method of getting rail expanded while welding ... but evidently it works for some!)
Over time, passage of trains and other effects (like longitudinal creep from braking) put additional stresses into the track structure. That is predominantly what the 'de-stressing' is required for, as I understand it. I find it hard to believe that CSX would use a 'wrong' value for RNT and this alone would lead to an increased risk of kinking.
Band: Helllllooooo WORCHESTER! Audience: It's frigging pronounced WISTAH!
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Out of towner: Are there any good restaurants in Worchester? Bostonian: You're freakin' retahded! There ain't no Worcester around here. Unless you're talkin about Wistah!
C&NW, CA&E, MILW, CGW and IC fan
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