I live in the UK and I commute by train every day (and travel a fair bit by rail for other purposes). I often see lengths of steel rail neatly laid for storage between the tracks - presumably placed there for some forthcoming work to replace existing rails when they become worn.
These are usually very, very long, continuous pieces of steel rail - easily longer than several standard carriages - I haven’t tried measuring them (I guess I could do this by shooting video, then counting the number of sleepers under the rail), but I’m talking about lengths of steel track that are maybe 50 metres long or more.
How do they get them there? The example I saw this morning was stored into a curve of the track - so all the stored rail was also flexed into an appropriate curve - but if these rails are being transported to site on a train, they must be spanning multiple carriages in length and the whole construction must be designed so that the carried rails themselves flex when the train goes around a bend.
I’m sure that wouldn’t be a problem for carrying a single rail, but if they’re delivering dozens of rails to site, how does the combined stiffness of the collection not cause a problem?
BTW, I’m aware that track is joined by welding during installation, but I’m talking about lengths of track at site awaiting installation. I do not believe this has been delivered in shorter lengths and welded together into long ones before fitting in place.
Those are the summer rails Mangetout. As many know the rails are longer in summer but what isn’t appreciated is the work that goes into replacing the short winter rails with the longer summer ones. It’s a heck of a chore.
I did see a rail-laying train operating once and it was a fairly major piece of kit. Easily long enough to take major lengths of track and I suspect they try and minimise the number of welds overall and so multiple 10’s of metres doesn’t seem too out of the ordinary. As for storage, they probably just keep stacks at strategic locations and crane them on to the track-layer as required.
The ones I have seen being moved are always just short of the length of a low loader trailer and these are pre assembled with the sleepers in place.
I’ve also seen the Personal Trackwork Safety (PST) certificate being taught for aspiring railway workers where they are taught the basic labouring tasks that might be expected of a maintenance crew and those tracks are the same length.
If I get the chance, in a couple of weeks time, and if I remember, I’ll have a word with one of the training staff since they have many years in the UK rail industry.
Mt WAG is that they transport the rail there in more manageable lengths and then weld them ready to lay. The objective is to reduce the time the track is out of use to a minimum, so anything that they can do in advance, will be done.
If you watch this video, you can see that the track is already welded in one long rail before the machine gets hold of it. - YouTube
But I gather that if you have 500 metres of rail in chute wagons, you drive that rain really really slowly.
But the rail company may weld them near the track to speed installation, and so be dealing with 500 metres of rail that are transported rather carefully to the actual installation site.
I gather the long lengths seen were welded together and dropped in that situation. That is, a welding wagon pulled stock off wagons, welded them on the fly, and dragged it out to drop onto the ground, ready for installation. The track installer system will come along and make use of it…
As I said in post #2, I don’t think this is true (at least not here in the UK. The lengths I’m seeing are uniformly oxidised along their entire (very long) length, from the moment they arrive in position (I know this because I have specifically looked for evidence of welds on a set of tracks that appeared in temporary storage position at a station I use every day.
Sure - what I find surprising is the idea of transporting lots of them in parallel - one rail will probably bend like a strip of licorice at the scale we’re talking about, but the resistance to bending is compounded as you add more strands.
Also, the rails on the inside of a bend will tend to ‘push’ at the ends - and those on the outside of the bend will ‘pull’ - I guess they must be anchored at one end only and allowed to slide along their length to compensate.
Rail is very flexible. Starting at about 40’, rail will bend under it’s own weight. So straight 1300+’ pieces will have no problem bending around curves while being transported to the installation site. They are then bent (using a variety of methods) to the necessary curvature when installed.
I have seen a photo of it, and it is awesome. But you will just to believe me for the moment. It was about 40 years ago in a rail geek magazine my father used to get. It was a shot taken looking down the length of a train as it traversed a slight S in the tracks. There was at least 500 feet, and maybe the full 700, of many rails on the train, all bending with the shape of the track. Remember the track itself is bent that much and happily sits flat without issue. I suspect the biggest problem with such a deliver train is the lateral forces on the wheel flanges. Wear is probably an issue, and the constant threat of derailing. But it clearly works.
That’s the factor (the only factor) that’s confounding me. I wonder if the track carrying vehicles have hydraulics to actively counteract the spring of the rails.
I’d have to find the materiel properties of rail track to run real numbers, but my guess is that the bending moment and spring force of the rails bending is nowhere near enough to have any meaningful effect vs. the weight of the cars. Like I said earlier, track is “flimsy” enough laterally that it will bend under it’s own weight if not handled properly.
There must still be some clever engineering at work somewhere - because the only place the train ‘bends’ is at the couplings between carriages.
So if the lengths of track were constrained laterally at both ends of each carriage, then its a much shorter length of steel that’s being flexed (the length of the gap between carriages)
You can see that the constraint point on the cars are inset a considerable distance from the edge of the cars. So on a curve the rail will bend between the constraint on car A and the one on car B, not just the gap between the two cars. The distance between those two points are far enough that the curvature will not be severe (no pinching). Now I’m not an engineer (just an engineering student) but It doesn’t look like a situation that will require considerable engineering to compensate for.
