I was noticing that none of the rail joints on the branch line that runs nearby are between the ties and not on them. At every joint the rail is bent down and looks like a wash board when looking down the line. Why dont they put ties under the joints for support? Wouldnt the rails last longer? Just think how smoother the track would be. Joint bars must be under tremendous stress when the wheels roll over them. When the locomotive comes down the line it realy gets rockin. There must be a reason but I cant figure it. Hopefully one of you guys can shed some light on this.
…Sorry Pete, don’t have an answer for you. I’ve wondered the same thing for years. Many of the joints I’ve observed do have them over a tie but perhaps not all. Must be a real strain on the joint bars and personally, I wonder why that isn’t a mechanism for loosing the bolts with all the “working action” each time a train passes over them.
Based on no particular authority, I would observe first that the ties are put in place before the rails are with no knowledge of where a joint will occur. That being said, the extra effort and manpower to relocate ties, etc, during track laying would probably have slowed down the process of laying those rails considerably.
Second, the joint bars probably have greater cross-section together than the web of the rail, thus should have a greater moment of inertia along the vertical axis and with approximately equivalent metal would handle the stresses as well, so long as the bolts are properly tightened. That’s where those big air wrenches came into play.
Finally, with respect to rail life and ride smoothness, I suspect that the current answers are that given that this is a branch line the rail lasts long enough and the ride is smooth enough, which is the criteria that the company must use. (I’m an engineer, so when you ask me if the glass is half full or half empty, I will tell you you made the glass twice the size you needed.[:)])
I put this up, as I say, as a gap filler opinion until mudchicken can put the exact answer up for us.
…As for strength at the joint bar vers. along the solid rail…it is a fact one can see low spots {often}, at the joint bar location. Perhaps even when the tie is not fully out from under that location.
I would agree with ChuckC. (I’ve never seen an exact diisertation on the subject either AFAICR, the point has been moot for so many years that the FRA std. assumes two joint support ties and it all seems logical.)[%-)]
(1) You are supporting the whole joint where the track modulus is trying to be bolstered/stiffened by the addition of bars and fasteners.
(2) You are supporting the places where the most adverse mechanical actions take place on the joints and make the joint less stiff (the bolts working loose)…also part of the difference between 4 and 6 hole joints - Keep the mechanical forces at play away from the bolts because they will fail first which is why permanent huck bolts did not work well in general application.
(3) I have seen proportionally more broken bars at a fully supported joint location than at places where joint ties at either end of the bar have resulted. (kind of like breaking a stick over your knee vs. doing the same over both knees)
(4) the chances of both ties failing under a joint bar is lesser than just one tie under the bolt.
I never thought of the stick over the knee scenario. Makes sense when you look at that way. Rail and bars have to do a lot of flexing when the train goes bye. Its true that the bolt and holes would be the weak point. Huck bolts may have looked good on paper but in the real world there is no advantage to them. The ones they put in truck frames have not been to good. We still have cracks and failures in xmembers and frames. Especialy on vocational trucks that go off road often.
Ah, yes, I see something kind of obvious from this, now. The joint will undergo twice as much flexing if it is actually resting on a tie, as opposed to between ties, because before the wheel rolls over the joint, the downward deflection of the rail will cause a flex of the joint, and then the same will occur after the wheel has passed the joint, whereas the joint with supports on either side should experience only one flex cycle as the wheel passes.
Now I should find my 58-year-old Railroad Engineering book and see that somebody figured that out a long time ago, I guess. This is just the kind of problem that brings the fun into engineering before management finds out and crushes it out like a stale cigar.
Edited later:
I dug out the book; it’s actually only 55 years old. It had an interesting
All track is subject to stress, be it from heat, age or rolling tonnage and requires maintenace at regular intervals. Branch line and siding/ yard tracks seldom see much maintenance and therefore the stresses eventualy take a toll. For example, the high speed Amtrak lines recieve almost constant maintenance and are put down on concrete ties with continuous welded rail, seldom have I seen much geometrical irregularities with this type of track and it regularly sees speeds of 150mph. Opposite this is the Bay Shore RR (formerly the Eastern Shore RR) who’s track is so bad it is limited to 10mph with speed restrictions in certain areas and gives a nice teeth rattling ride on the rollercoaster that used to be rail (ties are actualy flipped over to use the “good” side in an effort to save money).
Track is repaired in order to be safe, and allow the train to run at a proper speed. If there are broken rails or bad ties, speed must be dropped and profits fall for the railroad as trains now run slower.
For a good example of track repair compare the before and after pictures of this CSX trackage in Portage IN. The galloping track is clearly seen in the before photo, one pass later with a Dyna-CAT leaves smooth and level track. Many branch lines can’t afford a CAT, so maintenance is done accordingly.
Now, why are joints between the ties? Near as I can tell it makes fixing them much easier. There is no tie plate or spikes/clips to get in the way. Does it have anything to do with rail strength or durability? I don’t know for certain but I would much rather make a repair between ties than over one…
…Those machines sure do a great job in changing the appearance of track after passing over it and surely must make the alignment that much better…both vertically and horizontally.
Just thinking all that had to be done by labor and strong backs some decades ago.
It is beyond my comprehension how railroad track stays in place as well as it does…Especially the areas that are not served with enough maintenance.
If you have a shortline, you don’t want a CAT (Continuous Action Tamper). The larger railroads that own them do NOT always use them properly or commit to use them regularly - causing all kinds of grief. Fast?-yes, effective-sometimes?, costwise efficient?-No. If you have mud, switches and/or lots of curves - find something else that can do more than skinlift. The CAT machines have a place and purpose, but get used too often in other places where they should have been left in the hole.
If the roadmaster here was asking for a surfacing gang, he will still be asking for a surfacing gang and new ballast. (there are plenty of maintenance supervisors on railroads who have no clue about these machines or their limitations and are under more pressure to keep the thing working than to give the local roadmaster what he really needs and can use to his advantage)
Rail joints over ties, that’s nothing. I wonder why for years I have observed bad spots on a UP mainline in Oregon. Right now I know of several spots in a 2 mile section of track where up to 5 ties are floating, I mean where the ties are 1 to 11/2 inches below the rail. Yes, these spots are pumping mud and the rail ends are bent down a bit. This is welded rail but the problems are at occaisional joints where repairs were done or by turnouts.
There are about 20 trains a day and what really suprises me is that the trains don’t seem to have much problem passing over these spots. The springs seem to compensate and the locomotives hardly rock.
Is this common? How big of a bump does a crew have to feel on a mainline before they write it up?
Think of a Huck Bolt as a very large threaded rivet. Once you set the thing you cannot take a wrench to it to tighten-up. Takes a special tool to apply. All you can do is cut it off (and no matter what they say, the things do get loose)…most commonly seen in CWR insulated joints (bondos/welded-bonded insulated joints) sometimes seen in place of frog bolts (bad idea) and with transit clips in switch points (awful idea).
Regarding “down” ties, you can safely run up to 60 mph if 2/3rds of your ties are bad in a rail length (24 ties every 39 feet) as long as the good ties are properly distributed and are supporting the joints [FRA 49CFR213.109] and I bet the roadmaster and the track inspector are watching that section of track carefully. (and cursing the CSX beancounter mentality that they are stuck with at the same time)…
[most of the folks whining about CSX are too young to remember the disastrous PC days and that chickensh*t mindset]
Wow! It’s like this thread subject read my mind! (Doesn’t take long). I was wondering a similar thing but with me it was the welded areas of continuous rail, which I would assume are a little weaker, that never seem to be on the ties, I notice this all the time and it just seems like a vulnerable area to me.
