I watched today (and yesturday) the CN crews changing out the jointed rail to welded/ribbon (probably used, haven’t gotten close enough to look at the date) on the Manitowoc line (90/100lbs to 112 lbs(saw the tie plates before the rail was laid)). Last month, CN upgraded the main line thru Neenah with new 136 lb (from 112lb) welded rail. Few years ago, they changed the same rail with 112lb rail (same as it was before).
My question is this: Why do railroads change welded/ribbon rail more often than jointed rails? I’ve seen the old MILW mainline thru Wisconsin with a time stamp of 1956 up until the SOO LINE/CP did the major downgrading of the double main. Since then, that rail has been changed out at least once (railfan trip that day) if not twice. I know that the MILW ran some fast freights along with even faster passenger trains on that jointed rail. Why does it seem that the continuious rail needs changing out more often?
If I had to guess, I would have to say that since the rail is welded, it flexes and gets brittle faster than jointed rail, but I can’t be sure. Another thing could be that the rail is more likely to suffer from metal fatigue since it can’t expand and contract as easily as jointed rail. Again, this is all speculation on my part, but it seems to make sense in my head.
No, it’s actually the other way around. Think what happens to the rail at the point with low stiffness – the joint. That’s the Achilles Heel of jointed rail.
Rail replacement is primarily dependent upon gross tonnage. Lines with high gross tonnage usually are laid with welded rail. It gets more wear → it needs more frequent replacement. That’s all there is to it!
Then is the determining factor for replacing welded rail the aggregate number of tons, or are other factors considered, such as the average weight per car or per train? Does time have any consideration (probably not), but how about temperature extremes?
Where to start… I’ll give some of the basics and let others fill in some details.
To a large extent the argument is financial. The maintenance costs for CWR are more favorable, especially given the ever increasing tonnages being run. Joints are something that takes all of the pounding of every wheel. They wear out and need a lot of TLC compared to no joints. Bad joints cause more wear and tear on the ties next to them. Bad ties agravate the bad joint in an ever increasing death spiral. Slow orders cost money, let alone the money to fix the bad joint and tie locations. Take that times a joint every 39’ on each rail versus no joints and it adds up.
With more trains there is also less track time to fix things, so you want something as simple as possible out there. Add to that the decrease in people to do the work (take your pick on the chicken/egg question there) and you add to the value of CWR.
CWR has a different set of issues around it than jointed rail. Nothing is ever free. What you get rid of in on going maintenance of joints you add to the roadmaster’s gray hair development in making sure the track doesn’t pull apart in the winter or buckle in the summer.
As to replacement frequencies and using your example of the former Milwaukee mains across Wisconsin, when we rebuilt that from double track ABS into single track CTC in the late 80’s/early 90’s, we used a lot of second hand rail pulled up from the released main that was cropped and welded into CWR.
Replacement of rail, especially CWR, is driven by such things as defect history, total tonnage over it, wear in curves, etc. All of these things go in the mix to prioritize when any stretch is replaced. What you mostly see is a focus on curves. Wear usually drives replacement there and railroads will selectively analyze things and just repalce the high rail on one curve rather than doing several miles out of face, fo