We’ve talked a bit about cable splicing in the past, but never focused much on the process of actually making a cable. Today we resolve that.
Here is a short video (albeit in French) that demonstrates how small steel cables are wound together to create medium-sized cables, which are then spun again with other medium-sized cables to create the final super cable — the same one used in cable propelled transit systems.
I think the shear magnitude of the machines involved in this process is impressive. So is the final 5m diameter spool, which weighed in at around 150 tons!
Also, I find it reassuring that there are tests conducted all through out the process that test for strength and consistency, and that these are done both manually and with lasers.
It would be interesting to know about how long it takes to make one spool of cable.
14 Comments
The limit on cable length and dimensions are dictated by transport – Redaelli of Italy beated the world record making a 3 kms cable of 161 mm. diameter in one reel of 361 tons.
Since it was destined for offshore use, sea transport was easy.
That simply means that the actual dimensions of ropeways in general could be scaled-up if necessary, for example doubling or tripling Roosevelt Island ATW cab size and PPH
Here the image of the reel
http://www.teci.it/news/2.asp?idnews=55&page=1
Limitations on cable length will never be a true impediment to overall ropeway length. There are other more pressing factors relating to propulsion equipment, feasibility of ropeway/guideway maintenance, etc.
Here is a link to a video in English:
http://m.youtube.com/#/watch?v=eDVf71xd2cQ&desktop_uri=%2Fwatch%3Fv%3DeDVf71xd2cQ
Hi Julia, are you informed about any transit cable manufacturer that would be willing to do cable weaving on site (at least partially)? Using some sort of weaving technique like the one bridge manufacturers use on long suspension bridges? For the location in mind, a 100+ton spool is out of the question (no roads and can´t touch the landscape); but 20ton threads could be “airborned” (transported by a Mi-26 helicopter), and then these lighter threads finally woven into a larger diameter cable.
Julia, now, regarding the astonishing data about spool size & weight, do you happen to know where the cable you are talking about was deployed and the name of the system where the cable is part of? Please, elaborate if you have the time. By the way, Thanks for your note.
This is done in-factory. You can’t make a haul rope on site. The only thing you do on-site is the final splice.
Thanks Sean for clearing that up. Back to the drawing board.
Ciao Giorgio. I am under the impression that you are well informed about the present capabilities of the cable industry. By any chance, are you aware of any cable manufacturer that had built a 5km long cable (no splicings) used for suspension or even traction purposes, transit or any other application, delivered on a single spool? Have you heard of any manufacturer willing to make a few 5km spools, to be suspended on two towers?
Giorgio, I did some manual number crunching using two vanishing points for a perspective drawing (superimposed on the picture) and using the workers average height as a reference, I came up with a ~5m Flange Diameter for the spool in the picture (in the link you provided). Please correct me if I am wrong. Now, is the cable some sort of anchoring system for an offshore rig? Seems too massive for towing purposes? I don’t recall a cable that long and thick on a mega crane, not even the ones capable of handling thousands of metric tons (unless it is going to be chopped into shorter pieces). What´s the bending radius on a cable this size? Please, do bother to inform us. I find the topic fascinating. Grazie mille. Arrivederci.
Yes, the record cable is for Offshore use – anchoring I guess. On Redaelli.com site will find also infos about admitted bending radius (usually 50 to 100 times the ø )
As I said the limit regarding cables is actually the transport, and is not possible to made them on-site.
Sometimes on difficult terrains the cables are transported by unwinding the reel and haul the rope with winches to rewind on another reel.
Long and time-consuming (you need to place pulleys to avoid rope damage) but cheap respect bridge upgrading .
In the past were built material ropeways longer than 50 kilometers – with change of the rope in the intermediate towers.
In the near future we’ll see big advances in rope tech and performances with the introduction of composites
Giorgio, molto grazie. I will take into account what you mentioned about transporting the cable uphill, along the slopes if possible. I might have to rethink the tower locations to go across the valley. Sad to know, no transit cable manufacturer is willing or has ever tried to weave on site like suspension bridge cable people do.
…Because its simply not feasible – a ø 48 mm. rope common used on MGD is a 6 X 25 or 6 x 31 – that means that you need to weave in absolute contemporaneity 150 or 188 single steel wires of about 3,2 mm ø – and you need to gave each wire the correct (strong) tension as well head-weld each wire to obtain the right length of the rope .
It takes big machinery , big spaces into a controlled environment to ensure the safety of the rope.
If want to talk more about it, you’ll find me at my nickname at gmail.com
Let me thank you Sean for calling my attention, on those important factors to consider, when planning and designing an aerial cable transit system. The phrase “There are other more pressing factors” still resonates in my ears. It is one of those moments when you think “I better listen to what the gentleman has got so say”. Please if you have the time, Could you elaborate on the particular maintenance feasibility issues (or at least mention them), to be taken into account for an extra long span? Is that what you implied? I hope I am not putting you on the spot. I don’t want to sound over simplistic, to say the least, but if one needs to deploy a very long span system, say 5km long, with no intermediate towers, isn’t it just a matter of using a bigger tool when you talk about propulsion and maintenance? I can infer that these parameters don’t grow directly proportional (but rather exponentially) to the size of the cable. But beefier towers, sturdier pulleys and guideways, and more powerful electric motors with more robust foundations, with the associated larger hydraulic dampers, wouldn’t simply do the trick? The financial feasibility is not the priority (ROI is not part of the equation) since it will be financed and run by an state agency, used to the notion of subsidizing the fair, but of course it cannot go beyond reasonable limits, like costing what you would end up paying for a full blown adhesion metro line capable of carrying 50.000pphpd.
Sean, since the intended cable is for a 5.000 pphpd (or more) urban aerial transit system, one better take safety seriously; so, do you know of any real time cable integrity monitoring system capable of detecting loose threads, cable elongation, cable diameter being compromised or any dynamic disturbances (various frequency vibrations), at the station and on onboard cabins? Has anybody installed thermal imaging (or more conventional thermo-couplers) to detect overheating in pulleys, gears, bearings at the engine room and/or towers)? What about vibration detectors (on bearings, etc) like they use on high RPM turbine generators or permanent running engines or motors attached to water pumps or electric generators? What about real-time (not portable) laser based or ultrasound testing gear to detect cracks on shafts ore any other traction or structural component? Are these ideas too far-fetched? I would really appreciate the time and effort you are going to put at answering some or all of my questions. Best regards, I hope I am not “imposing my welcome”, and again thank you.
Roger, I’ll answer questions in order. These are only my opinion:
1) Long span systems are feasible, especially where there are only a limited number of towers, thus keeping tower equipment (and more importantly maintenance required) to a minimum. The problem for me is where you get into urban environments where you want to increase the number of towers, stations, cabins, etc. I would prefer to have two smaller, integrated ropeways to bridge a 5km span, as opposed to one single ropeway. This makes maintenance easier, improves operational reliability, etc. Evacuating a 5km gondola system would be extremely time consuming.
But if you are building a system to span a single geographic span (like a mountain, gorge, etc, then sure, build as long as possible and just increase size of motors, etc.
2) The haul rope is the safest part of a system. They are nearly indestructible if maintained properly. Basic maintenance includes frequent measuring of splice diameter to ensure splice isn’t thinning (which means rope pulling apart) and to ensure no obvious structural abnormalities. Every 6-12 months you just perform an electromagnetic NDT to fully ensure structural integrity.
3) Not a problem to install temperature, noise, and vibration sensors on equipment. This is common and is done on all major components. NDT is performed on all safety-related grips, axles, shafts, etc, as determined by regulatory bodies and manufacturers. As far as ropeways go, these components are also very reliable in my experience.
Hope this helps. Moral of the story is longer ropeway is not always better. But this assessment is very specific to the environment in which a system is to be installed and the operational expectations of the owner.
Sean, thank you very much. It certainly does help a lot. I am reading carefully every single piece of info, advices, tips you shared. I will try for next time around, to have a drawing of the intended route to better explain myself if you are willing to bear with me longer.
As you figured it out, The sketched route is a mixed route, including an urban section, a suburban section, and a plain country side section where thre is no alternative but to go across a wide geographic gap (5km wide valley). The idea is to interconnect a dormitory city on a high plateau at 1500mts with a mayor metropolitan area on the other side of the mountains, in a deep valley at 600mts, hopping from mountain peak to mountain peak, and trying to serve intermediate closed communities, colleges, scientific research centers and the like, to gain additional support.