Lifespan of ties
From: "SK Jagasia" skjagasia@patilgroup.com
Request you to help in getting these answers please:
1.0 How the calculate life of Wooden ties laid under rail with respect to Gross Million ton pass?
2.0 What is expected Life of a steel channel ties / composite ties life?
3.0 Life of steel channel ties with respect to Pre stress concrete ties over same Gross Million ton pass?
S K Jagasia
Vice President - Composite Sleeper
Patil Rail Infrastructure Pvt Ltd.
Secunderabad, India
posted from CPRR Discussion Group at 7:31 AM
3 Comments:
From: ANDREW DOW
This question comes from someone who, perhaps one may assume, has a need to know about the life of ties in current conditions. Clearly, the three answers need to be compatible if any comparisons are to be made.
One hundred years ago, W.M. Camp, in his classic book Notes on Track: Construction and Maintenance, gave widely varying lives for ties according to wood, treatment, and the ballast in which they were laid. Since then, steel and concrete ties have been developed, as have mechanical tamping and ballast cleaning. Steel ties are more affected by local atmospheric conditions (which promote corrosion) while concrete ties tend to be fretted away from underneath by the ballast. Wood ties can be treated according to local conditions, but a good engineer might choose another material. Wood ties can be laid by hand, but concrete ties are so heavy that they demand machines.
The list could go on. Perhaps we should suggest that the enquirer should consider the use of a consulting engineer well acquainted with the area in which ties are to be laid. Straight comparisons are difficult to make.
—Andrew Dow
[from the R&LHS Newsgroup.]
From: Dick Dawson
Andrew Dow is correct about the widely differing lives of crossties, depending on local conditions. Wooden ties can live a remarkably long time, up to 40 years, in optimal conditions. If high tonnage is to be carried around curves, concrete and steel ties retain gauge much better than wood ties. The type of rail securement, whether cut spikes (wood ties only) or direct fixation, such as Pandrol clips, makes a significant difference as well. Thus, you may see a railroad that carries unit coal trains using wood ties and cut spikes on tangent track and concrete ties with Pandrol clips on curved portions of the same line.
One possible source of information is AREMA, the American Railway Engineering and Maintenance of Way Association, formerly AREA, the American Railway Engineering Association. It is the counterpart of the AAR for track, bridge and building professionals and can be reached at 301-459-3200 (telephone), 301-459-8077 (fax), or at www.arema.com. I don't know how much information they give out to non-members, but they may have material for sale. In any event, these are the people who really know.
—Dick Dawson
[from the R&LHS Newsgroup.]
From: Crew Heimer
Key Sources to check – there was a Federal Railroad Administration study from the late 1970's (1978?) done by the TOPS folks at Southern Pacific.
Zeta-tech has made a business out of supplying such answers.
Also see Wiliam W. Hay's book Railroad Engineeering.
And the answer is – that it all depends
At less than 3 million gross tons per year on straight track – the tie will rot first. There are charts as to tie life by area. Basically - warmer climes = faster rot and wetter climes = faster rot. But cold and wet, or hot and dry still has pretty good life.
South Georgia, Florida and humid Gulf Coast average tie life is a maximum 15-20 years before even considering mechanical wear. Is it any surprise that FEC has concrete ties. Little noticed is that ACL & SAL together installed many more ties than FEC – but they were too early and had fastener problems so those concrete ties have been removed.
Maine – cold and wet – probably has an average tie life of 35-40 year on light density lines.
Now for some fun observations:
While walking the former CV tunnel north of Burlington, Vermont in the late 1990's – all the ties had 1928 date nails. This is a tunnel through sand – dry with good drainage the ties were all 70 years old and notice – that they all had been replaced following the great flood!
Santa Fe's Escondido Branch (California – now the NCTD sprinter line) in 1990 had many ties from the 1920's – about two-thirds of the ties were before 1930 on tangents while only a few percent had survived on the sharp curves - moderate but dry climate.
On former UP branches – Eastern Idaho shortline – in the late 1990's there were many ties still in place from the 1920's & 30's – Cold and light railfall.
On Kyle Railroad – in mid Kansas there was a dramatic shift in tie life within a few miles. They joked about it occurring at the 100th Meridian - but regardless - ties west of the line had dramatically longer lives (and were older) than ties east of the line. Since temperatures were similar both east & west, it was interesting to see that there is a point at which a slight reduction in rainfall results in significantly longer tie life.
Factors that reduce tie life – curves and grades (and soft versus hardwoods and size of tie plate). In the 1990's BN developed a concrete tie program for curves – ('course they were still trying to use softwood ties at some locations). If one can find monster tieplates – they extend rail life on curves.
Why did tie plates come into common use - when ties started to be preserved. Previously the maximum life of an untreated white oak tie was about 8 years - no point in worrying about rail abrasion if the tie had to be replaced in 8 years anyway.
As we face oil shortages – look back a century and there were major concerns that life as we knew it was about to end as we would use all our wood up. Railroads were using over 100 Million ties a year in maintenance and construction as well as wood for structures and railcars. See a great book The Depletion Myth: A History of Railroad Use of Timber by Sherry H. Olson.
Crew Heimer
Project Manager
It is the mission of GRTA /GDC to improve Georgia's mobility, air quality and land use practices.
[from the R&LHS Newsgroup.]
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